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Saturday, August 25, 2018

Breakthrough in construction of computers for mimicking human brain

Artist's concept (stock image).
Credit: © Andrey / Fotolia
A computer built to mimic the brain's neural networks produces similar results to that of the best brain-simulation supercomputer software currently used for neural-signaling research, finds a new study published in the open-access journal Frontiers in Neuroscience. Tested for accuracy, speed and energy efficiency, this custom-built computer named SpiNNaker, has the potential to overcome the speed and power consumption problems of conventional supercomputers. The aim is to advance our knowledge of neural processing in the brain, to include learning and disorders such as epilepsy and Alzheimer's disease.
"SpiNNaker can support detailed biological models of the cortex -- the outer layer of the brain that receives and processes information from the senses -- delivering results very similar to those from an equivalent supercomputer software simulation," says Dr. Sacha van Albada, lead author of this study and leader of the Theoretical Neuroanatomy group at the Jülich Research Centre, Germany. "The ability to run large-scale detailed neural networks quickly and at low power consumption will advance robotics research and facilitate studies on learning and brain disorders."
The human brain is extremely complex, comprising 100 billion interconnected brain cells. We understand how individual neurons and their components behave and communicate with each other and on the larger scale, which areas of the brain are used for sensory perception, action and cognition. However, we know less about the translation of neural activity into behavior, such as turning thought into muscle movement.
Supercomputer software has helped by simulating the exchange of signals between neurons, but even the best software run on the fastest supercomputers to date can only simulate 1% of the human brain.
"It is presently unclear which computer architecture is best suited to study whole-brain networks efficiently. The European Human Brain Project and Jülich Research Centre have performed extensive research to identify the best strategy for this highly complex problem. Today's supercomputers require several minutes to simulate one second of real time, so studies on processes like learning, which take hours and days in real time are currently out of reach." explains Professor Markus Diesmann, co-author, head of the Computational and Systems Neuroscience department at the Jülich Research Centre.
He continues, "There is a huge gap between the energy consumption of the brain and today's supercomputers. Neuromorphic (brain-inspired) computing allows us to investigate how close we can get to the energy efficiency of the brain using electronics."
Developed over the past 15 years and based on the structure and function of the human brain, SpiNNaker -- part of the Neuromorphic Computing Platform of the Human Brain Project -- is a custom-built computer composed of half a million of simple computing elements controlled by its own software. The researchers compared the accuracy, speed and energy efficiency of SpiNNaker with that of NEST -- a specialist supercomputer software currently in use for brain neuron-signaling research.
"The simulations run on NEST and SpiNNaker showed very similar results," reports Steve Furber, co-author and Professor of Computer Engineering at the University of Manchester, UK. "This is the first time such a detailed simulation of the cortex has been run on SpiNNaker, or on any neuromorphic platform. SpiNNaker comprises 600 circuit boards incorporating over 500,000 small processors in total. The simulation described in this study used just six boards -- 1% of the total capability of the machine. The findings from our research will improve the software to reduce this to a single board."
Van Albada shares her future aspirations for SpiNNaker, "We hope for increasingly large real-time simulations with these neuromorphic computing systems. In the Human Brain Project, we already work with neuroroboticists who hope to use them for robotic control."

Engineers develop artificial intelligence system to detect often-missed cancer tumors

Assistant Professor Ulas Bagci leads the group of engineers at the University of Central Florida that have taught a computer how to detect tiny specks of lung cancer in CT scans, which radiologists often have a difficult time identifying. The artificial intelligence system is about 95 percent accurate, compared to 65 percent when done by human eyes, the team said.
Credit: University of Central Florida, Karen Norum
Doctors may soon have help in the fight against cancer thanks to the University of Central Florida's Computer Vision Research Center.
Engineers at the center have taught a computer how to detect tiny specks of lung cancer in CT scans, which radiologists often have a difficult time identifying. The artificial intelligence system is about 95 percent accurate, compared to 65 percent when done by human eyes, the team said.
"We used the brain as a model to create our system," said Rodney LaLonde, a doctoral candidate and captain of UCF's hockey team. "You know how connections between neurons in the brain strengthen during development and learn? We used that blueprint, if you will, to help our system understand how to look for patterns in the CT scans and teach itself how to find these tiny tumors."
The approach is similar to the algorithms that facial-recognition software uses. It scans thousands of faces looking for a particular pattern to find its match.
Engineering Assistant Professor Ulas Bagci leads the group of researchers in the center that focuses on AI with potential medical applications.
The group fed more than 1,000 CT scans -- provided by the National Institutes of Health through a collaboration with the Mayo Clinic -- into the software they developed to help the computer learn to look for the tumors.
Graduate students working on the project had to teach the computer different things to help it learn properly. Naji Khosravan, who is pursuing his doctorate degree, created the backbone of the system of learning. His proficiency at novel machine learning and computer vision algorithms led to his summer as an intern at Netflix helping the company with various projects.
LaLonde taught the computer how to ignore other tissue, nerves and other masses it encountered in the CT scans and analyze lung tissues. Sarfaraz Hussein who earned his doctorate degree this past summer, is fine-tuning the AI's ability to identify cancerous versus benign tumors, while graduate student Harish Ravi Parkash is taking lessons learned from this project and applying them see if another AI system can be developed to help identify or predict brain disorders.
"I believe this will have a very big impact," Bagci said. "Lung cancer is the number one cancer killer in the United States and if detected in late stages, the survival rate is only 17 percent. By finding ways to help identify earlier, I think we can help increase survival rates."
The team will present its finding in September at the largest premier conference for medical imaging research -- the MICCAI 2018 conference in Spain. The team's work has been published in advance of the conference.
The next step is to move the research project into a hospital setting; Bagci is looking for partners to make that happen. After that, the technology could be a year or two away from the marketplace, Bagci said.
"I think we all came here because we wanted to use our passion for engineering to make a difference and saving lives is a big impact," LaLonde said.
Ravi Prakash agrees. He was studying engineering and its applications to agriculture before he heard about Bagci and his work at UCF. Bagci's research is in the area of biomedical imaging and machine learning and their applications in clinical imaging. Previously, Bagci was a staff scientist and the lab manager at the NIH's Center for Infectious Disease Imaging lab, in the department of Radiology and Imaging Sciences.

Google AI team improves Linkify on Android Pie

The Google AI team strives towards solutions that make the user’s life simple. With the launch of Tensorflow, the deep learning team has taken the power of machine learning to almost all the Google Products. Smart replies on Gmail, better photographs on Google camera, translation and text completion are some of the features that we have been using for a while. And now, Android Pie stands at the top of the line for an enhancement to Linkify.

Android Pie

Google has been at the forefront of AI development the past couple of years. It has embedded AI deep within Android  9(codenamed Pie) to make the smartphones personalized and intuitive for users. Though most of these features are subtle and don’t bring about a massive difference in usage, some enhancements are noteworthy.
The Linkify is a feature on Android that adds clickable links to texts. This allows users to take faster action. For example, if your friend sends you a text message containing a phone number. The phone numbers are usually clickable, and upon clicking, it opens it up in the dialer app. Here’s an example on the phone
linkify
The linkify here is identified based on a set of rules. If none of the rules match, then no link will be added to it. And so, we wonder why a phone number is not getting highlighted.
Now you know!
With the Android Pie, the Linkify no longer works based on a set of rules. Google has used machine learning to train the linkify system to identify different types of data and add clickable links appropriately. This is called Smart Linkify.

Smart Linkify

android Pie
The most notable feature of the Smart Linkify feature is the ability to detect addresses and turn them into clickable links. These addresses are auto-detected and you can directly open them through Google Maps. Along with addresses, the existing features such as phone numbers, email, etc are detected in a much smarter way.
The reason they are smarter is because of the Neural network that has been put in place. It will not follow rules but try to understand what is being talked about. It tries to identify patterns by analyzing text around the area of interest. Here is an example:
If you received a text which read, “Your order is shipped, and the confirmation number is 857-555-3556.” Here the area of interest would be the number “857-555-3556” as it looks like a phone number. Earlier versions of Linkify would have recognized this as a phone number, but the Smart Linkify on Android Pie will identify that the context does not hint for that number to be a phone number and it will not add the clickable link to it. This is the power of AI.
If you are interested in learning how to build AI-powered applications and how machine learning works, I would recommend you to check out this course on Machine Learning and Deep Learning.

Android Pie Developers

It’s good news for Android Pie developers as they can efficiently use all of these features while building mobile applications. The Smart Linkify feature has been open sourced and available as a TensorFlow API on the Android Pie.
Source: Google AI Blog

3 Ways Artificial Intelligence Will Change Digital Marketing


From Apple’s intelligent assistant siri to self driving cars from Tesla to Google AI that can learn video games in a very short period, Artificial Intelligence is transforming industries one after other. The very next aim of AI would be the field of digital marketing which is already evolving dynamically.
AI carries a huge potential in the digital marketing field, with the support of AI in providing great customer experience, targeted marketing and predictive analysis will surely provide a better ROI to enterprises.
The relationship between Digital Marketing and AI
In the past, marketers were uncertain about implementing AI into their strategies. But these years have witnessed considerable trust amongst the marketers with regards to application of AI. This is because of the decrease in the ambiguity considering the results as many sectors have already gathered important benefits.
Artificial Intelligence has made a huge presence through its subsidiary processes like the big data, machine learning and internet of things. But these are only elements that will contribute eventually towards releasing the total potential of AI. The upcoming days will see impact and visible changes due to the application of Artificial Intelligence.
Let us wait and watch in what ways AI will considerably impact digital marketing in the near future. There following are the areas where AI can show its impact towards digital marketing. These possible changes are still in the basic stage now, but can be a cutting-edge for AI-powered digital marketing.
  1. Customizing user experience
This is highly critical area where AI can break through and make a significant impact. Content is crucial for a marketer similarly the customer is important for every business. If he can align the strategy of content marketing with AI, it could be pathbreaking. Depending on data collected such as buying behaviour, customer searches and interests, personalized content campaigns can be organized.
Another great example of AI are chatbots, they are crucial in enhancing user experience. They are programmed in such a way that they can respond to customers based on the data they receive. Traditional text communication and chatbox will slowly become extinct giving rise to a new way of communication system with sensory abilities such as touch and voice. Google Duplex is a great example of chatbots.
2. Simplifying decision making with Predictive Marketing
Every time a user searches on the web-browser; new data is generated and gathered for AI analysis. This data can disclose user information such as behaviors, needs, and future actions. Depending on this information, the marketing process can be enhanced to deliver the most relevant information. Outreach through social media can unveil personal information regarding the prospect making it simpler for marketers to build a targeted campaign.
This process slows down the sales-cycle as the similar information is supplied to customers on a silver plate. Decision making can be made easier with predictive campaigns by significantly decreasing customer research on the product. However the marketers can continue to study the buyer through data and even attract the customer to return.
The AI-enabled algorithms will overtake the current practices like SEO in a huge way. With artificial intelligence supporting the digital marketing initiatives form initial level, chances of trends such as search engine optimization, banner advertisements becoming obsolete are high. This process gives you a detailed report of your prospect without the need of SEO and website traffic.
3. Using image recognition to get maximum ROI
In the past, recognizing an image was confined to identify isolated objects in a portrait. Now, with the help of AI, It becomes easy to get a detailed description of an image. Amazon Rekognition is a new innovation from Amazon which can actually identify objects, recognize human faces and their emotions.
This innovation can be implemented in many ways for many sectors. For financial and banking sector, Recognising image with AI-enabled software can be leveraged for enhanced customer security and faster payment process. Social media is the main source for images.
Conclusion
Thanks to big data and social media outreach, we now understand customers far better than we ever did. AI and its associated technologies should bring customers and marketers closer in the future.
With AI as the bridge between them, it would be fascinating to see how digital marketing turns out in future. Better sales-cycle, predictive buying and selling, and optimized decision making are confirmed outcomes of this robotic war. However both the brands and customers would win the battle.

What is AI? Ten things you need to know about the future of artificial intelligence

The history of artificial intelligence (AI)dates back to antiquity – intelligent robots appear in the myths of many ancient societies, including Greek, Arabic, Egyptian and Chinese. Today, the field of artificial intelligence is more vibrant than ever and some believe that we're on the threshold of discoveries that could change human society irreversibly, for better or worse.
To truly understand what AI is, though, you need to appreciate the jargon that's thrown around out there right now. For instance, you need to know that artificial intelligence is not the same as machine learning, despite the fact it's regularly used as a synonym for it. The chief difference to remember is that machine learning is simply a process by which a computer can learn a skill, whereas artificial intelligence refers to a computer that can "think" for itself without being programmed to do so.
Facebook's head of AI research, Yann Lecun explains what AI is rather eloquently in an introduction to AI education.
Now we've cleared that up, here are ten things you need to know about AI before the robots take over the world:

1. Artificial intelligence is developing faster than you think, and speeding up exponentially

Humans tend to think in straight lines, but every aspect of technological progress is actually accelerating – including AI. Futurist Ray Kurzweil calls this the “Law of Accelerating Returns”, and presents evidence that an amount of progress equal to the entire 20th century's gains was attained between 2000 and 2014. He also argues that the same amount will happen again before 2021. Understanding the exponential nature of progress and ignoring the inner tendency to think things will keep improving at the same rate is key to getting to grips with how fast we'll make scientific advances in the future.

2. You use artificial intelligence all day, every day

SiriGoogle Now, and Cortana are obvious examples of artificial intelligence, but AI is actually all around us. It can be found in vacuum cleaners, cars, lawnmowers, video games, Hollywood special effects, e-commerce software, medical research and international finance markets – among many other examples. John McCarthy, who originally coined the term “artificial intelligence” in 1956, famously quipped: “As soon as it works, no-one calls it AI anymore.”

3. Robots are definitely going to take your job

Yeah, I know you're a special flower and everything, but the work you do is either already automatable or will be very soon. How soon? Most jobs will be done by robots within 30 years, says professor Moshe Vardi of Rice University, leading to unemployment rates greater than 50%. That might sound bad, but many academics studying the field believe that technological unemployment will open the door to a future where work is something people do for pleasure, not out of necessity. Proposals such as universal basic income are the beginnings of a societal support structure that could eventually allow this to become a reality.

4. About half of the AI community believes computers will be as smart as humans by 2040

In 2013, two researchers surveyed hundreds of AI experts on when they thought there was a 50/50 chance that human-level artificial intelligence will arrive. The median answer was 2040 – only 24 years from now. The average life expectancy in the UK is 82 years, meaning that there's a heads/tails chance that a 58-year-old today will see computers as smart as humans in their lifetime. Another recent study from author James Barratsimply asked researchers when human-level AI would be achieved – by 2030, 2050, 2100, after 2100 or never. The largest group, 42% of respondents, said before 2030.

5. A lot of smart people think developing artificial intelligence to human level is a dangerous thing to do

6. Once artificial intelligence gets smarter than humans, we've got very little chance of understanding it
Once machines are as intelligent as a human, a lot of worrying things can happen. There's little chance that AI development would cease at that point (the AI would almost certainly begin working on improving itself) and many very smart people – including Stephen Hawking and Elon Musk – think that this situation would be very scary indeed. “If I had to guess at what our biggest existential threat is, it’s probably that. So we need to be very careful,” said Musk during a recent interview. “I’m increasingly inclined to think that there should be some regulatory oversight, maybe at the national and international level, just to make sure that we don’t do something very foolish.”

Tim Urban, at Wait But Why, explains this really well in his pair of enormous articles on artificial intelligence, so I'll quote him here: “A chimp can become familiar with what a human is and what a skyscraper is, but he’ll never be able to understand that the skyscraper was built by humans,” he writes. “We will never be able to even comprehend the things a [superintelligent AI] can do, even if the machine tried to explain it to us – let alone do it ourselves. It could try for years to teach us the simplest inkling of what it knows and the endeavor would be hopeless.”

7. There's no such thing as an “evil” artificial intelligence

Contrary to what we see in sci-fi and movies, AI can't be evil. That's a human concept. An AI can do unspeakably horrible things, but it doesn't do them out of sheer wickedness – it does them simply because that's what it has been programmed (intentionally or accidentally) to do. Stephen Hawking explained this concept recently in an AMA on Reddit. “A super-intelligent AI will be extremely good at accomplishing its goals,” he said, “and if those goals aren't aligned with ours, we're in trouble.”

8. There are three ways a superintelligent artificial intelligence could work

AI expert Nick Bostrom, in his fantastic book Superintelligence: Paths, Dangers, Strategies, classifies three ways in which a superintelligence could operate. An “oracle” would be able to answer questions with a good degree of accuracy. A “genie” would do anything it is commanded to do and then await the next command, while a “sovereign” would be assigned an overarching goal and then be allowed to operate in the world and make decisions about how best to accomplish that goal. For the reasons above, the former is much less scary than the latter.

9. Artificial intelligence could be the reason why we've never met aliens

Further up, Elon Musk described AI as an “existential threat” to humanity, meaning that it could erase mankind from the universe entirely. This ties in with ideas of a “Great Filter” that kills off alien civilisations that reach a certain level of technological development. It's entirely possible that the reason we've never met aliens is because they invented artificial intelligence before they could build spaceships capable of interstellar travel, and that discovery caused their extinction.

10. Basically, there's a good chance we'll be extinct or immortal by the end of the century

The world of AI research is roughly split into optimists and pessimists. The optimists hope that we'll one day invent a superintelligence that solves every problem we can imagine and leads us into a utopian future where all of mankind's needs are met and everyone lives happily ever after. The pessimists are concerned that one tiny mistake along the way will lead to the swift end of the human race – as an AI programmed to solve climate change, for example, identifies that humans are the number one obstacle to doing so. There are also scenarios in between, of course – where would a reality such as The Matrix, where humans are cultivated as a fuel source in a state of perfect happiness, lie on that scale?
For now, you can leave your opinion in the comments section below. But it likely won't be very long until we find out for real.

Wednesday, August 22, 2018

Artificial intelligence

Artificial intelligence (AI), the ability of a digital computer or computer-controlled robot to perform tasks commonly associated with intelligent beings. The term is frequently applied to the project of developing systems endowed with the intellectual processes characteristic of humans, such as the ability to reason, discover meaning, generalize, or learn from past experience. Since the development of the digital computer in the 1940s, it has been demonstrated that computers can be programmed to carry out very complex tasks—as, for example, discovering proofs for mathematical theorems or playing chess—with great proficiency. Still, despite continuing advances in computer processing speed and memory capacity, there are as yet no programs that can match human flexibility over wider domains or in tasks requiring much everyday knowledge. On the other hand, some programs have attained the performance levels of human experts and professionals in performing certain specific tasks, so that artificial intelligence in this limited sense is found in applications as diverse as medical diagnosis, computer search engines, and voice or handwriting recognition.
READ MORE ON THIS TOPIC
Figure 1: Position of chessmen at the beginning of a game. They are queen's rook (QR), queen's knight (QN), queen's bishop (QB), queen (Q), king (K), king's bishop (KB), king's knight (KN), king's rook (KR); the chessmen in front of these pieces are the pawns.
chess: Chess and artificial intelligence
Machines capable of playing chess have fascinated people since the latter half of the 18th century, when the Turk, the first of the pseudo-automatons, began a triumphal exhibition tour of Europe. Like its 19th-century successor Ajeeb, the Turk was a cleverly constructed cabinet…

What Is Intelligence?

All but the simplest human behaviour is ascribed to intelligence, while even the most complicated insect behaviour is never taken as an indication of intelligence. What is the difference? Consider the behaviour of the digger waspSphex ichneumoneus. When the female wasp returns to her burrow with food, she first deposits it on the threshold, checks for intruders inside her burrow, and only then, if the coast is clear, carries her food inside. The real nature of the wasp’s instinctual behaviour is revealed if the food is moved a few inches away from the entrance to her burrow while she is inside: on emerging, she will repeat the whole procedure as often as the food is displaced. Intelligence—conspicuously absent in the case of Sphex—must include the ability to adapt to new circumstances.
Psychologists generally do not characterize human intelligence by just one trait but by the combination of many diverse abilities. Research in AI has focused chiefly on the following components of intelligence: learning, reasoning, problem solving, perception, and using language.

Learning

There are a number of different forms of learning as applied to artificial intelligence. The simplest is learning by trial and error. For example, a simple computer program for solving mate-in-one chess problems might try moves at random until mate is found. The program might then store the solution with the position so that the next time the computer encountered the same position it would recall the solution. This simple memorizing of individual items and procedures—known as rote learning—is relatively easy to implement on a computer. More challenging is the problem of implementing what is called generalization. Generalization involves applying past experience to analogous new situations. For example, a program that learns the past tense of regular English verbs by rote will not be able to produce the past tense of a word such as jump unless it previously had been presented with jumped, whereas a program that is able to generalize can learn the “add ed” rule and so form the past tense of jump based on experience with similar verbs.

Reasoning

To reason is to draw inferences appropriate to the situation. Inferences are classified as either deductive or inductive. An example of the former is, “Fred must be in either the museum or the café. He is not in the café; therefore he is in the museum,” and of the latter, “Previous accidents of this sort were caused by instrument failure; therefore this accident was caused by instrument failure.” The most significant difference between these forms of reasoning is that in the deductive case the truth of the premises guarantees the truth of the conclusion, whereas in the inductive case the truth of the premise lends support to the conclusion without giving absolute assurance. Inductive reasoning is common in science, where data are collected and tentative models are developed to describe and predict future behaviour—until the appearance of anomalous data forces the model to be revised. Deductive reasoning is common in mathematics and logic, where elaborate structures of irrefutable theorems are built up from a small set of basic axioms and rules.
There has been considerable success in programming computers to draw inferences, especially deductive inferences. However, true reasoning involves more than just drawing inferences; it involves drawing inferences relevant to the solution of the particular task or situation. This is one of the hardest problems confronting AI.

Problem solving

Problem solving, particularly in artificial intelligence, may be characterized as a systematic search through a range of possible actions in order to reach some predefined goal or solution. Problem-solving methods divide into special purpose and general purpose. A special-purpose method is tailor-made for a particular problem and often exploits very specific features of the situation in which the problem is embedded. In contrast, a general-purpose method is applicable to a wide variety of problems. One general-purpose technique used in AI is means-end analysis—a step-by-step, or incremental, reduction of the difference between the current state and the final goal. The program selects actions from a list of means—in the case of a simple robot this might consist of PICKUP, PUTDOWN, MOVEFORWARD, MOVEBACK, MOVELEFT, and MOVERIGHT—until the goal is reached.
Many diverse problems have been solved by artificial intelligence programs. Some examples are finding the winning move (or sequence of moves) in a board game, devising mathematical proofs, and manipulating “virtual objects” in a computer-generated world.

Perception

In perception the environment is scanned by means of various sensory organs, real or artificial, and the scene is decomposed into separate objects in various spatial relationships. Analysis is complicated by the fact that an object may appear different depending on the angle from which it is viewed, the direction and intensity of illumination in the scene, and how much the object contrasts with the surrounding field.
At present, artificial perception is sufficiently well advanced to enable optical sensors to identify individuals, autonomous vehicles to drive at moderate speeds on the open road, and robots to roam through buildings collecting empty soda cans. One of the earliest systems to integrate perception and action was FREDDY, a stationary robot with a moving television eye and a pincer hand, constructed at the University of Edinburgh, Scotland, during the period 1966–73 under the direction of Donald Michie. FREDDY was able to recognize a variety of objects and could be instructed to assemble simple artifacts, such as a toy car, from a random heap of components.

Language

language is a system of signs having meaning by convention. In this sense, language need not be confined to the spoken word. Traffic signs, for example, form a minilanguage, it being a matter of convention that {hazard symbol} means “hazard ahead” in some countries. It is distinctive of languages that linguistic units possess meaning by convention, and linguistic meaning is very different from what is called natural meaning, exemplified in statements such as “Those clouds mean rain” and “The fall in pressure means the valve is malfunctioning.”
An important characteristic of full-fledged human languages—in contrast to birdcalls and traffic signs—is their productivity. A productive language can formulate an unlimited variety of sentences.
It is relatively easy to write computer programs that seem able, in severely restricted contexts, to respond fluently in a human language to questions and statements. Although none of these programs actually understands language, they may, in principle, reach the point where their command of a language is indistinguishable from that of a normal human. What, then, is involved in genuine understanding, if even a computer that uses language like a native human speaker is not acknowledged to understand? There is no universally agreed upon answer to this difficult question. According to one theory, whether or not one understands depends not only on one’s behaviour but also on one’s history: in order to be said to understand, one must have learned the language and have been trained to take one’s place in the linguistic community by means of interaction with other language users.

Methods And Goals In AI

Symbolic vs. connectionist approaches

AI research follows two distinct, and to some extent competing, methods, the symbolic (or “top-down”) approach, and the connectionist (or “bottom-up”) approach. The top-down approach seeks to replicate intelligence by analyzing cognition independent of the biological structure of the brain, in terms of the processing of symbols—whence the symbolic label. The bottom-up approach, on the other hand, involves creating artificial neural networks in imitation of the brain’s structure—whence the connectionist label.
To illustrate the difference between these approaches, consider the task of building a system, equipped with an optical scanner, that recognizes the letters of the alphabet. A bottom-up approach typically involves training an artificial neural network by presenting letters to it one by one, gradually improving performance by “tuning” the network. (Tuning adjusts the responsiveness of different neural pathways to different stimuli.) In contrast, a top-down approach typically involves writing a computer program that compares each letter with geometric descriptions. Simply put, neural activities are the basis of the bottom-up approach, while symbolic descriptions are the basis of the top-down approach.
In The Fundamentals of Learning (1932), Edward Thorndike, a psychologist at Columbia UniversityNew York City, first suggested that human learning consists of some unknown property of connections between neurons in the brain. In The Organization of Behavior (1949), Donald Hebb, a psychologist at McGill University, Montreal, Canada, suggested that learning specifically involves strengthening certain patterns of neural activity by increasing the probability (weight) of induced neuron firing between the associated connections. The notion of weighted connections is described in a later section, Connectionism.
In 1957 two vigorous advocates of symbolic AI—Allen Newell, a researcher at the RAND CorporationSanta Monica, California, and Herbert Simon, a psychologist and computer scientist at Carnegie Mellon University, Pittsburgh, Pennsylvania—summed up the top-down approach in what they called the physical symbol system hypothesis. This hypothesisstates that processing structures of symbols is sufficient, in principle, to produce artificial intelligence in a digital computer and that, moreover, human intelligence is the result of the same type of symbolic manipulations.
During the 1950s and ’60s the top-down and bottom-up approaches were pursued simultaneously, and both achieved noteworthy, if limited, results. During the 1970s, however, bottom-up AI was neglected, and it was not until the 1980s that this approach again became prominent. Nowadays both approaches are followed, and both are acknowledged as facing difficulties. Symbolic techniques work in simplified realms but typically break down when confronted with the real world; meanwhile, bottom-up researchers have been unable to replicate the nervous systems of even the simplest living things. Caenorhabditis elegans, a much-studied worm, has approximately 300 neurons whose pattern of interconnections is perfectly known. Yet connectionist models have failed to mimic even this worm. Evidently, the neurons of connectionist theory are gross oversimplifications of the real thing.

Strong AI, applied AI, and cognitive simulation

Employing the methods outlined above, AI research attempts to reach one of three goals: strong AI, applied AI, or cognitive simulation. Strong AI aims to build machines that think. (The term strong AI was introduced for this category of research in 1980 by the philosopher John Searle of the University of California at Berkeley.) The ultimate ambition of strong AI is to produce a machine whose overall intellectual ability is indistinguishable from that of a human being. As is described in the section Early milestones in AI, this goal generated great interest in the 1950s and ’60s, but such optimism has given way to an appreciation of the extreme difficulties involved. To date, progress has been meagre. Some critics doubt whether research will produce even a system with the overall intellectual ability of an ant in the forseeable future. Indeed, some researchers working in AI’s other two branches view strong AI as not worth pursuing.
Applied AI, also known as advanced information processing, aims to produce commercially viable “smart” systems—for example, “expert” medical diagnosis systems and stock-trading systems. Applied AI has enjoyed considerable success, as described in the section Expert systems.
In cognitive simulation, computers are used to test theories about how the human mind works—for example, theories about how people recognize faces or recall memories. Cognitive simulation is already a powerful tool in both neuroscience and cognitive psychology.

Alan Turing And The Beginning Of AI

Theoretical work

The earliest substantial work in the field of artificial intelligence was done in the mid-20th century by the British logician and computer pioneer Alan Mathison Turing. In 1935 Turing described an abstract computing machine consisting of a limitless memory and a scanner that moves back and forth through the memory, symbol by symbol, reading what it finds and writing further symbols. The actions of the scanner are dictated by a program of instructions that also is stored in the memory in the form of symbols. This is Turing’s stored-program concept, and implicit in it is the possibility of the machine operating on, and so modifying or improving, its own program. Turing’s conception is now known simply as the universal Turing machine. All modern computers are in essence universal Turing machines.
During World War II, Turing was a leading cryptanalyst at the Government Code and Cypher School in Bletchley Park, Buckinghamshire, England. Turing could not turn to the project of building a stored-program electronic computing machine until the cessation of hostilities in Europe in 1945. Nevertheless, during the war he gave considerable thought to the issue of machine intelligence. One of Turing’s colleagues at Bletchley Park, Donald Michie (who later founded the Department of Machine Intelligence and Perception at the University of Edinburgh), later recalled that Turing often discussed how computers could learn from experience as well as solve new problems through the use of guiding principles—a process now known as heuristic problem solving.
Turing gave quite possibly the earliest public lecture (London, 1947) to mention computer intelligence, saying, “What we want is a machine that can learn from experience,” and that the “possibility of letting the machine alter its own instructions provides the mechanism for this.” In 1948 he introduced many of the central concepts of AI in a report entitled “Intelligent Machinery.” However, Turing did not publish this paper, and many of his ideas were later reinvented by others. For instance, one of Turing’s original ideas was to train a network of artificial neurons to perform specific tasks, an approach described in the section Connectionism.

Chess

At Bletchley Park, Turing illustrated his ideas on machine intelligence by reference to chess—a useful source of challenging and clearly defined problems against which proposed methods for problem solving could be tested. In principle, a chess-playing computer could play by searching exhaustively through all the available moves, but in practice this is impossible because it would involve examining an astronomically large number of moves. Heuristics are necessary to guide a narrower, more discriminative search. Although Turing experimented with designing chess programs, he had to content himself with theory in the absence of a computer to run his chess program. The first true AI programs had to await the arrival of stored-program electronic digital computers.
In 1945 Turing predicted that computers would one day play very good chess, and just over 50 years later, in 1997, Deep Blue, a chess computerbuilt by the International Business Machines Corporation (IBM), beat the reigning world champion, Garry Kasparov, in a six-game match. While Turing’s prediction came true, his expectation that chess programming would contribute to the understanding of how human beings think did not. The huge improvement in computer chess since Turing’s day is attributable to advances in computer engineering rather than advances in AI—Deep Blue’s 256 parallel processors enabled it to examine 200 million possible moves per second and to look ahead as many as 14 turns of play. Many agree with Noam Chomsky, a linguist at the Massachusetts Institute of Technology (MIT), who opined that a computer beating a grandmaster at chess is about as interesting as a bulldozer winning an Olympic weightlifting competition.

The Turing test

In 1950 Turing sidestepped the traditional debate concerning the definition of intelligence, introducing a practical test for computer intelligence that is now known simply as the Turing test. The Turing test involves three participants: a computer, a human interrogator, and a human foil. The interrogator attempts to determine, by asking questions of the other two participants, which is the computer. All communication is via keyboard and display screen. The interrogator may ask questions as penetrating and wide-ranging as he or she likes, and the computer is permitted to do everything possible to force a wrong identification. (For instance, the computer might answer, “No,” in response to, “Are you a computer?” and might follow a request to multiply one large number by another with a long pause and an incorrect answer.) The foil must help the interrogator to make a correct identification. A number of different people play the roles of interrogator and foil, and, if a sufficient proportion of the interrogators are unable to distinguish the computer from the human being, then (according to proponents of Turing’s test) the computer is considered an intelligent, thinking entity.
In 1991 the American philanthropist Hugh Loebner started the annual Loebner Prize competition, promising a $100,000 payout to the first computer to pass the Turing test and awarding $2,000 each year to the best effort. However, no AI program has come close to passing an undiluted Turing test.

Early Milestones In AI

The first AI programs

The earliest successful AI program was written in 1951 by Christopher Strachey, later director of the Programming Research Group at the University of Oxford. Strachey’s checkers (draughts) program ran on the Ferranti Mark I computer at the University of Manchester, England. By the summer of 1952 this program could play a complete game of checkers at a reasonable speed.
Information about the earliest successful demonstration of machine learning was published in 1952. Shopper, written by Anthony Oettinger at the University of Cambridge, ran on the EDSAC computer. Shopper’s simulated world was a mall of eight shops. When instructed to purchase an item, Shopper would search for it, visiting shops at random until the item was found. While searching, Shopper would memorize a few of the items stocked in each shop visited (just as a human shopper might). The next time Shopper was sent out for the same item, or for some other item that it had already located, it would go to the right shop straight away. This simple form of learning, as is pointed out in the introductory section What is intelligence?, is called rote learning.
The first AI program to run in the United States also was a checkers program, written in 1952 by Arthur Samuel for the prototype of the IBM 701. Samuel took over the essentials of Strachey’s checkers program and over a period of years considerably extended it. In 1955 he added features that enabled the program to learn from experience. Samuel included mechanisms for both rote learning and generalization, enhancements that eventually led to his program’s winning one game against a former Connecticut checkers champion in 1962.

Evolutionary computing

Samuel’s checkers program was also notable for being one of the first efforts at evolutionary computing. (His program “evolved” by pitting a modified copy against the current best version of his program, with the winner becoming the new standard.) Evolutionary computing typically involves the use of some automatic method of generating and evaluating successive “generations” of a program, until a highly proficient solution evolves.
A leading proponent of evolutionary computing, John Holland, also wrote test software for the prototype of the IBM 701 computer. In particular, he helped design a neural-network “virtual” rat that could be trained to navigate through a maze. This work convinced Holland of the efficacy of the bottom-up approach. While continuing to consult for IBM, Holland moved to the University of Michigan in 1952 to pursue a doctorate in mathematics. He soon switched, however, to a new interdisciplinary program in computers and information processing (later known as communications science) created by Arthur Burks, one of the builders of ENIAC and its successor EDVAC. In his 1959 dissertation, for most likely the world’s first computer science Ph.D., Holland proposed a new type of computer—a multiprocessor computer—that would assign each artificial neuron in a network to a separate processor. (In 1985 Daniel Hillis solved the engineering difficulties to build the first such computer, the 65,536-processor Thinking Machines Corporation supercomputer.)
Holland joined the faculty at Michigan after graduation and over the next four decades directed much of the research into methods of automating evolutionary computing, a process now known by the term genetic algorithms. Systems implemented in Holland’s laboratory included a chess program, models of single-cell biological organisms, and a classifier system for controlling a simulated gas-pipeline network. Genetic algorithms are no longer restricted to “academic” demonstrations, however; in one important practical application, a genetic algorithm cooperates with a witness to a crime in order to generate a portrait of the criminal.

Logical reasoning and problem solving

The ability to reason logically is an important aspect of intelligence and has always been a major focus of AI research. An important landmark in this area was a theorem-proving program written in 1955–56 by Allen Newell and J. Clifford Shaw of the RAND Corporation and Herbert Simonof the Carnegie Mellon University. The Logic Theorist, as the program became known, was designed to prove theorems from Principia Mathematica (1910–13), a three-volume work by the British philosopher-mathematicians Alfred North Whitehead and Bertrand Russell. In one instance, a proof devised by the program was more elegant than the proof given in the books.
Newell, Simon, and Shaw went on to write a more powerful program, the General Problem Solver, or GPS. The first version of GPS ran in 1957, and work continued on the project for about a decade. GPS could solve an impressive variety of puzzles using a trial and error approach. However, one criticism of GPS, and similar programs that lack any learning capability, is that the program’s intelligence is entirely secondhand, coming from whatever information the programmer explicitly includes.

English dialogue

Two of the best-known early AI programs, Eliza and Parry, gave an eerie semblance of intelligent conversation. (Details of both were first published in 1966.) Eliza, written by Joseph Weizenbaum of MIT’s AI Laboratory, simulated a human therapist. Parry, written by Stanford University psychiatrist Kenneth Colby, simulated a human paranoiac. Psychiatrists who were asked to decide whether they were communicating with Parry or a human paranoiac were often unable to tell. Nevertheless, neither Parry nor Eliza could reasonably be described as intelligent. Parry’s contributions to the conversation were canned—constructed in advance by the programmer and stored away in the computer’s memory. Eliza, too, relied on canned sentences and simple programming tricks.

AI programming languages

In the course of their work on the Logic Theorist and GPS, Newell, Simon, and Shaw developed their Information Processing Language (IPL), a computer language tailored for AI programming. At the heart of IPL was a highly flexible data structure that they called a list. A list is simply an ordered sequence of items of data. Some or all of the items in a list may themselves be lists. This scheme leads to richly branching structures.
In 1960 John McCarthy combined elements of IPL with the lambda calculus (a formal mathematical-logical system) to produce the programming language LISP (List Processor), which remains the principal language for AI work in the United States. (The lambda calculus itself was invented in 1936 by the Princeton logician Alonzo Church while he was investigating the abstract Entscheidungsproblem, or “decision problem,” for predicate logic—the same problem that Turing had been attacking when he invented the universal Turing machine.)
The logic programming language PROLOG (Programmation en Logique) was conceived by Alain Colmerauer at the University of Aix-Marseille, France, where the language was first implemented in 1973. PROLOG was further developed by the logician Robert Kowalski, a member of the AI group at the University of Edinburgh. This language makes use of a powerful theorem-proving technique known as resolution, invented in 1963 at the U.S. Atomic Energy Commission’sArgonne National Laboratory in Illinois by the British logician Alan Robinson. PROLOG can determine whether or not a given statement follows logically from other given statements. For example, given the statements “All logicians are rational” and “Robinson is a logician,” a PROLOG program responds in the affirmative to the query “Robinson is rational?” PROLOG is widely used for AI work, especially in Europe and Japan.
Researchers at the Institute for New Generation Computer Technology in Tokyo have used PROLOG as the basis for sophisticated logic programming languages. Known as fifth-generation languages, these are in use on nonnumerical parallel computers developed at the Institute.
Other recent work includes the development of languages for reasoning about time-dependent data such as “the account was paid yesterday.” These languages are based on tense logic, which permits statements to be located in the flow of time. (Tense logic was invented in 1953 by the philosopher Arthur Prior at the University of Canterbury, Christchurch, New Zealand.)

Microworld programs

To cope with the bewildering complexity of the real world, scientists often ignore less relevant details; for instance, physicists often ignore friction and elasticity in their models. In 1970 Marvin Minsky and Seymour Papert of the MIT AI Laboratory proposed that likewise AI research should focus on developing programs capable of intelligent behaviour in simpler artificial environments known as microworlds. Much research has focused on the so-called blocks world, which consists of coloured blocks of various shapes and sizes arrayed on a flat surface.
An early success of the microworld approach was SHRDLU, written by Terry Winograd of MIT. (Details of the program were published in 1972.) SHRDLU controlled a robot arm that operated above a flat surface strewn with play blocks. Both the arm and the blocks were virtual. SHRDLU would respond to commands typed in natural English, such as “Will you please stack up both of the red blocks and either a green cube or a pyramid.” The program could also answer questions about its own actions.Although SHRDLU was initially hailed as a major breakthrough, Winograd soon announced that the program was, in fact, a dead end. The techniques pioneered in the program proved unsuitable for application in wider, more interesting worlds. Moreover, the appearance that SHRDLU gave of understanding the blocks microworld, and English statements concerning it, was in fact an illusion. SHRDLU had no ideawhat a green block was.
Another product of the microworld approach was Shakey, a mobile robotdeveloped at the Stanford Research Institute by Bertram Raphael, Nils Nilsson, and others during the period 1968–72. The robot occupied a specially built microworld consisting of walls, doorways, and a few simply shaped wooden blocks. Each wall had a carefully painted baseboard to enable the robot to “see” where the wall met the floor (a simplification of reality that is typical of the microworld approach). Shakey had about a dozen basic abilities, such as TURN, PUSH, and CLIMB-RAMP.
Critics pointed out the highly simplified nature of Shakey’s environment and emphasized that, despite these simplifications, Shakey operated excruciatingly slowly; a series of actions that a human could plan out and execute in minutes took Shakey days.
The greatest success of the microworld approach is a type of program known as an expert system, described in the next section.

Expert Systems

Expert systems occupy a type of microworld—for example, a model of a ship’s hold and its cargo—that is self-contained and relatively uncomplicated. For such AI systems every effort is made to incorporate all the information about some narrow field that an expert (or group of experts) would know, so that a good expert system can often outperform any single human expert. There are many commercial expert systems, including programs for medical diagnosischemical analysis, credit authorization, financial management, corporate planning, financial document routing, oil and mineral prospecting, genetic engineeringautomobile design and manufacture, camera lens design, computerinstallation design, airline scheduling, cargo placement, and automatic help services for home computer owners.

Knowledge and inference

The basic components of an expert system are a knowledge base, or KB, and an inference engine. The information to be stored in the KB is obtained by interviewing people who are expert in the area in question. The interviewer, or knowledge engineer, organizes the information elicited from the experts into a collection of rules, typically of an “if-then” structure. Rules of this type are called production rules. The inference engine enables the expert system to draw deductions from the rules in the KB. For example, if the KB contains the production rules “if x, then y” and “if y, then z,” the inference engine is able to deduce “if x, then z.” The expert system might then query its user, “Is x true in the situation that we are considering?” If the answer is affirmative, the system will proceed to infer z.
Some expert systems use fuzzy logic. In standard logic there are only two truth values, true and false. This absolute precision makes vague attributes or situations difficult to characterize. (When, precisely, does a thinning head of hair become a bald head?) Often the rules that human experts use contain vague expressions, and so it is useful for an expert system’s inference engine to employ fuzzy logic.

DENDRAL

In 1965 the AI researcher Edward Feigenbaum and the geneticist Joshua Lederberg, both of Stanford University, began work on HeuristicDENDRAL (later shortened to DENDRAL), a chemical-analysis expert system. The substance to be analyzed might, for example, be a complicated compound of carbonhydrogen, and nitrogen. Starting from spectrographic data obtained from the substance, DENDRAL would hypothesize the substance’s molecular structure. DENDRAL’s performance rivaled that of chemists expert at this task, and the program was used in industry and in academia.

MYCIN

Work on MYCIN, an expert system for treating blood infections, began at Stanford University in 1972. MYCIN would attempt to diagnose patients based on reported symptoms and medical test results. The program could request further information concerning the patient, as well as suggest additional laboratory tests, to arrive at a probable diagnosis, after which it would recommend a course of treatment. If requested, MYCIN would explain the reasoning that led to its diagnosis and recommendation. Using about 500 production rules, MYCIN operated at roughly the same level of competence as human specialists in blood infections and rather better than general practitioners.
Nevertheless, expert systems have no common sense or understanding of the limits of their expertise. For instance, if MYCIN were told that a patient who had received a gunshot wound was bleeding to death, the program would attempt to diagnose a bacterial cause for the patient’s symptoms. Expert systems can also act on absurd clerical errors, such as prescribing an obviously incorrect dosage of a drug for a patient whose weight and age data were accidentally transposed.

The CYC project

CYC is a large experiment in symbolic AI. The project began in 1984 under the auspices of the Microelectronics and Computer Technology Corporation, a consortium of computer, semiconductor, and electronicsmanufacturers. In 1995 Douglas Lenat, the CYC project director, spun off the project as Cycorp, Inc., based in Austin, Texas. The most ambitious goal of Cycorp was to build a KB containing a significant percentage of the commonsense knowledge of a human being. Millions of commonsense assertions, or rules, were coded into CYC. The expectation was that this “critical mass” would allow the system itself to extract further rules directly from ordinary prose and eventually serve as the foundation for future generations of expert systems.
With only a fraction of its commonsense KB compiled, CYC could draw inferences that would defeat simpler systems. For example, CYC could infer, “Garcia is wet,” from the statement, “Garcia is finishing a marathon run,” by employing its rules that running a marathon entails high exertion, that people sweat at high levels of exertion, and that when something sweats it is wet. Among the outstanding remaining problems are issues in searching and problem solving—for example, how to search the KB automatically for information that is relevant to a given problem. AI researchers call the problem of updating, searching, and otherwise manipulating a large structure of symbols in realistic amounts of time the frame problem. Some critics of symbolic AI believe that the frame problem is largely unsolvable and so maintain that the symbolic approach will never yield genuinely intelligent systems. It is possible that CYC, for example, will succumb to the frame problem long before the system achieves human levels of knowledge.

Connectionism

Connectionism, or neuronlike computing, developed out of attempts to understand how the human brain works at the neural level and, in particular, how people learn and remember. In 1943 the neurophysiologist Warren McCulloch of the University of Illinois and the mathematician Walter Pitts of the University of Chicago published an influential treatise on neural nets and automatons, according to which each neuron in the brain is a simple digital processor and the brain as a whole is a form of computing machine. As McCulloch put it subsequently, “What we thought we were doing (and I think we succeeded fairly well) was treating the brain as a Turing machine.”

Creating an artificial neural network

It was not until 1954, however, that Belmont Farley and Wesley Clark of MIT succeeded in running the first artificial neural network—albeit limited by computer memory to no more than 128 neurons. They were able to train their networks to recognize simple patterns. In addition, they discovered that the random destruction of up to 10 percent of the neurons in a trained network did not affect the network’s performance—a feature that is reminiscent of the brain’s ability to tolerate limited damage inflicted by surgery, accident, or disease.
The simple neural network depicted in the figure illustrates the central ideas of connectionism. Four of the network’s five neurons are for input, and the fifth—to which each of the others is connected—is for output. Each of the neurons is either firing (1) or not firing (0). Each connection leading to N, the output neuron, has a “weight.” What is called the total weighted input into N is calculated by adding up the weights of all the connections leading to N from neurons that are firing. For example, suppose that only two of the input neurons, X and Y, are firing. Since the weight of the connection from X to N is 1.5 and the weight of the connection from Y to N is 2, it follows that the total weighted input to Nis 3.5. As shown in the figure, N has a firing threshold of 4. That is to say, if N’s total weighted input equals or exceeds 4, then N fires; otherwise, Ndoes not fire. So, for example, N does not fire if the only input neurons to fire are X and Y, but N does fire if XY, and Z all fire.
Training the network involves two steps. First, the external agent inputs a pattern and observes the behaviour of N. Second, the agent adjusts the connection weights in accordance with the rules:
  1. If the actual output is 0 and the desired output is 1, increase by a small fixed amount the weight of each connection leading to N from neurons that are firing (thus making it more likely that N will fire the next time the network is given the same pattern);
  2. If the actual output is 1 and the desired output is 0, decrease by that same small amount the weight of each connection leading to the output neuron from neurons that are firing (thus making it less likely that the output neuron will fire the next time the network is given that pattern as input).
The external agent—actually a computer program—goes through this two-step procedure with each pattern in a training sample, which is then repeated a number of times. During these many repetitions, a pattern of connection weights is forged that enables the network to respond correctly to each pattern. The striking thing is that the learning process is entirely mechanical and requires no human intervention or adjustment. The connection weights are increased or decreased automatically by a constant amount, and exactly the same learning procedure applies to different tasks.

Perceptrons

In 1957 Frank Rosenblatt of the Cornell Aeronautical Laboratory at Cornell University in Ithaca, New York, began investigating artificial neural networks that he called perceptrons. He made major contributions to the field of AI, both through experimental investigations of the properties of neural networks (using computer simulations) and through detailed mathematical analysis. Rosenblatt was a charismaticcommunicator, and there were soon many research groups in the United States studying perceptrons. Rosenblatt and his followers called their approach connectionist to emphasize the importance in learning of the creation and modification of connections between neurons. Modern researchers have adopted this term.
One of Rosenblatt’s contributions was to generalize the training procedure that Farley and Clark had applied to only two-layer networks so that the procedure could be applied to multilayer networks. Rosenblatt used the phrase “back-propagating error correction” to describe his method. The method, with substantial improvements and extensions by numerous scientists, and the term back-propagation are now in everyday use in connectionism.

Conjugating verbs

In one famous connectionist experiment conducted at the University of California at San Diego (published in 1986), David Rumelhart and James McClelland trained a network of 920 artificial neurons, arranged in two layers of 460 neurons, to form the past tenses of English verbs. Root forms of verbs—such as comelook, and sleep—were presented to one layer of neurons, the input layer. A supervisory computer programobserved the difference between the actual response at the layer of output neurons and the desired response—came, say—and then mechanically adjusted the connections throughout the network in accordance with the procedure described above to give the network a slight push in the direction of the correct response. About 400 different verbs were presented one by one to the network, and the connections were adjusted after each presentation. This whole procedure was repeated about 200 times using the same verbs, after which the network could correctly form the past tense of many unfamiliar verbs as well as of the original verbs. For example, when presented for the first time with guard, the network responded guarded; with weepwept; with clingclung; and with dripdripped (complete with double p). This is a striking example of learning involving generalization. (Sometimes, though, the peculiarities of English were too much for the network, and it formed squawked from squatshipped from shape, and membled from mail.)
Another name for connectionism is parallel distributed processing,which emphasizes two important features. First, a large number of relatively simple processors—the neurons—operate in parallel. Second, neural networks store information in a distributed fashion, with each individual connection participating in the storage of many different items of information. The know-how that enabled the past-tense network to form wept from weep, for example, was not stored in one specific location in the network but was spread throughout the entire pattern of connection weights that was forged during training. The human brain also appears to store information in a distributed fashion, and connectionist research is contributing to attempts to understand how it does so.

Other neural networks

Other work on neuronlike computing includes the following:
  • Visual perception. Networks can recognize faces and other objects from visual data. A neural network designed by John Hummel and Irving Biederman at the University of Minnesota can identify about 10 objects from simple line drawings. The network is able to recognize the objects—which include a mug and a frying pan—even when they are drawn from different angles. Networks investigated by Tomaso Poggio of MIT are able to recognize bent-wire shapes drawn from different angles, faces photographed from different angles and showing different expressions, and objects from cartoon drawings with gray-scale shading indicating depth and orientation.
  • Language processing. Neural networks are able to convert handwritten and typewritten material to electronic text. The U.S. Internal Revenue Service has commissioned a neuronlike system that will automatically read tax returns and correspondence. Neural networks also convert speech to printed text and printed text to speech.
  • Financial analysis. Neural networks are being used increasingly for loan risk assessment, real estate valuation, bankruptcy prediction, share price prediction, and other business applications.
  • Medicine. Medical applications include detecting lung nodules and heartarrhythmias and predicting adverse drug reactions.
  • TelecommunicationsTelecommunications applications of neural networks include control of telephone switching networks and echo cancellation in modems and on satellite links.

Nouvelle AI

New foundations

The approach now known as nouvelle AI was pioneered at the MIT AI Laboratory by the Australian Rodney Brooks during the latter half of the 1980s. Nouvelle AI distances itself from strong AI, with its emphasis on human-level performance, in favour of the relatively modest aim of insect-level performance. At a very fundamental level, nouvelle AI rejects symbolic AI’s reliance upon constructing internal models of reality, such as those described in the section Microworld programs. Practitioners of nouvelle AI assert that true intelligence involves the ability to function in a real-world environment.
A central idea of nouvelle AI is that intelligence, as expressed by complex behaviour, “emerges” from the interaction of a few simple behaviours. For example, a robot whose simple behaviours include collision avoidance and motion toward a moving object will appear to stalk the object, pausing whenever it gets too close.
One famous example of nouvelle AI is Brooks’s robot Herbert (named after Herbert Simon), whose environment is the busy offices of the MIT AI Laboratory. Herbert searches desks and tables for empty soda cans, which it picks up and carries away. The robot’s seemingly goal-directed behaviour emerges from the interaction of about 15 simple behaviours. More recently, Brooks has constructed prototypes of mobile robots for exploring the surface of Mars. (See the photographs and an interview with Rodney Brooks.)
Herbert, the robot, c. 1987Designed by Rodney Brooks and affectionately named for artificial intelligence pioneer Herbert Simon, Herbert employed 30 infrared sensors, a laser scanner, and a magnetic compass to locate soft-drink cans and keep itself oriented as it wandered throughout the MIT Artificial Intelligence Laboratory. After collecting an empty can with its robotic arm, Herbert would return it to a recycling bin.© MIT, Artificial Intelligence Laboratory
Nouvelle AI sidesteps the frame problem discussed in the section The CYC project. Nouvelle systems do not contain a complicated symbolic model of their environment. Instead, information is left “out in the world” until such time as the system needs it. A nouvelle system refers continuously to its sensors rather than to an internal model of the world: it “reads off” the external world whatever information it needs at precisely the time it needs it. (As Brooks insisted, the world is its own best model—always exactly up-to-date and complete in every detail.)

The situated approach

Traditional AI has by and large attempted to build disembodied intelligences whose only interaction with the world has been indirect (CYC, for example). Nouvelle AI, on the other hand, attempts to build embodied intelligences situated in the real world—a method that has come to be known as the situated approach. Brooks quoted approvingly from the brief sketches that Turing gave in 1948 and 1950 of the situated approach. By equipping a machine “with the best sense organs that money can buy,” Turing wrote, the machine might be taught “to understand and speak English” by a process that would “follow the normal teaching of a child.” Turing contrasted this with the approach to AI that focuses on abstract activities, such as the playing of chess. He advocated that both approaches be pursued, but until recently little attention has been paid to the situated approach.
The situated approach was also anticipated in the writings of the philosopher Bert Dreyfus of the University of California at Berkeley. Beginning in the early 1960s, Dreyfus opposed the physical symbol system hypothesis, arguing that intelligent behaviour cannot be completely captured by symbolic descriptions. As an alternative, Dreyfus advocated a view of intelligence that stressed the need for a body that could move about, interacting directly with tangible physical objects. Once reviled by advocates of AI, Dreyfus is now regarded as a prophet of the situated approach.
Critics of nouvelle AI point out the failure to produce a system exhibiting anything like the complexity of behaviour found in real insects. Suggestions by researchers that their nouvelle systems may soon be conscious and possess language seem entirely premature.

Is Strong AI Possible?

The ongoing success of applied AI and of cognitive simulation, as described in the preceding sections of this article, seems assured. However, strong AI—that is, artificial intelligence that aims to duplicate human intellectual abilities—remains controversial. Exaggerated claims of success, in professional journals as well as the popular press, have damaged its reputation. At the present time even an embodied system displaying the overall intelligence of a cockroach is proving elusive, let alone a system that can rival a human being. The difficulty of scaling up AI’s modest achievements cannot be overstated. Five decades of research in symbolic AI have failed to produce any firm evidence that a symbol system can manifest human levels of general intelligence; connectionists are unable to model the nervous systems of even the simplest invertebrates; and critics of nouvelle AI regard as simply mystical the view that high-level behaviours involving language understanding, planning, and reasoning will somehow emerge from the interaction of basic behaviours such as obstacle avoidance, gaze control, and object manipulation.
However, this lack of substantial progress may simply be testimony to the difficulty of strong AI, not to its impossibility. Let us turn to the very idea of strong artificial intelligence. Can a computer possibly think? Noam Chomsky suggests that debating this question is pointless, for it is an essentially arbitrary decision whether to extend common usage of the word think to include machines. There is, Chomsky claims, no factual question as to whether any such decision is right or wrong—just as there is no question as to whether our decision to say that airplanes fly is right, or our decision not to say that ships swim is wrong. However, this seems to oversimplify matters. The important question is, Could it ever be appropriate to say that computers think, and, if so, what conditions must a computer satisfy in order to be so described?
Some authors offer the Turing test as a definition of intelligence. However, Turing himself pointed out that a computer that ought to be described as intelligent might nevertheless fail his test if it were incapable of successfully imitating a human being. For example, why should an intelligent robot designed to oversee mining on the Moonnecessarily be able to pass itself off in conversation as a human being? If an intelligent entity can fail the test, then the test cannot function as a definition of intelligence. It is even questionable whether passing the test would actually show that a computer is intelligent, as the information theorist Claude Shannon and the AI pioneer John McCarthypointed out in 1956. Shannon and McCarthy argued that it is possible, in principle, to design a machine containing a complete set of canned responses to all the questions that an interrogator could possibly ask during the fixed time span of the test. Like Parry, this machine would produce answers to the interviewer’s questions by looking up appropriate responses in a giant table. This objection seems to show that in principle a system with no intelligence at all could pass the Turing test.
In fact, AI has no real definition of intelligence to offer, not even in the subhuman case. Rats are intelligent, but what exactly must an artificial intelligence achieve before researchers can claim this level of success? In the absence of a reasonably precise criterion for when an artificial system counts as intelligent, there is no objective way of telling whether an AI research program has succeeded or failed. One result of AI’s failure to produce a satisfactory criterion of intelligence is that, whenever researchers achieve one of AI’s goals—for example, a program that can summarize newspaper articles or beat the world chess champion—critics are able to say “That’s not intelligence!” Marvin Minsky’s response to the problem of defining intelligence is to maintain—like Turing before him—that intelligence is simply our name for any problem-solving mental process that we do not yet understand. Minsky likens intelligence to the concept “unexplored regions of Africa”: it disappears as soon as we discover it.