Dipartimento di Elettronica Informazione e Bioingegneria Cognitive Robotics

Transcription

1 Dipartimento di Elettronica Informazione e Bioingegneria Cognitive Robotics Disciplines for the 2015

2 Interdisciplinarity More on Philosophy Neuroscience Psychology (and ethology) Anthropology Linguistics

3 Philosophy Theoretical / methodological questions What is mind? How can we know anything in principle? Philosophy of science SEP (Stanford Encyclopedia of Philosophy)

4 Duality mind - physical world anti-physicalism -the nature of mind is entirely distinct from physical nature. Cartesian dualism - mind interacts with the physical world under very rare conditions; the mode of interaction is impossible to understand and seems to conflict with elementary principles of physics. Idealism - mind is the sole ontological foundation of reality, supporting a physical world conceived of as entirely constructed out of mental phenomena.

5 Qualia Feelings and experiences vary widely. For example, I run my fingers over sandpaper, feel a sharp pain in my finger, become extremely angry. I am the subject of a mental state with a subjective character. Philosophers use the term qualia to refer to the introspectively accessible, phenomenal aspects of our mental lives Qualia are at the very heart of the mindbody problem.

6 Functionalism and qualia Functionalism is the view that individual qualia have functional natures, that the phenomenal character of, e.g., pain is one and the same as the property of playing a role in mediating between physical inputs (e.g., body damage) and physical outputs (e.g., withdrawal behavior). what makes something a mental state of a particular type does not depend on its internal constitution, but rather on the way it functions in the cognitive system of which it is a part qualia are multiply physically realizable they do not depend on the hardware

7 Who has qualia? Do frogs have qualia? Somewhere down the phylogenetic scale phenomenal consciousness ceases. But where? Darwin in his study on earth worms failed to find a threshold between high and low level animals

8 representationalism for a state to have phenomenal character is that (i) it carries information about certain features (ii) is such that this information is ready used to make a direct difference to beliefs and desires then creatures that are incapable of reasoning, of changing their behavior in light of assessments they make, based upon information provided by sensors, are not phenomenally conscious.

9 Plants and animals Consider, for example, the case of plants. There are many different sorts of plant behavior. Some plants climb, others eat flies, many plants close their leaves at night. The immediate cause of these activities is something internal to the plants. The behavior of plants is inflexible. It is genetically determined and, therefore, not modifiable by learning. Plants are not subject to any qualia.

10 Sense datum theory introduced in early 20th-century by H. H. Price, G. E. Moore, and B. Russell to denote that which we are directly aware of in perception. First, one has a sense datum. When one has a sense datum, one is necessarily immediately aware of that sense datum. This immediate awareness is known as sensing By virtue of this acquaintance, one is in a position to know that one has a sense datum of the kind that one in fact has. One then makes inferences about the physical world to explain the series of sense data that one has.

11 Sense data sense data have three defining characteristics: 1. Sense data are the kind of thing we are directly aware of in perception, 2. Sense data are dependent on the mind 3. Sense data have the properties that perceptually appear to us.

12 Perception and reality Sense data theorists believe that the things we are directly aware of in perception are dependent on the mind of the perceiver they cannot exist unperceived. See Hume: the thing we are directly aware of appears to change for instance, its apparent size changes. the real, external object does not change. therefore, the thing we are directly aware of is not the real external object.

13 Integrating mind and physics only two positions can promise the desired integration of body-mind: panpsychism and emergentism. Panpsychism's assertion that mind suffuses the universe is in sharp contrast with its basic rival, Emergentism, which asserts that mind appears only at certain times, in certain places under certain probably very special and very rare conditions.

14 Panpsychism Panpsychism is the doctrine that mind is a fundamental feature of the world which exists throughout the universe mind, in some sense of the term, is everywhere. Panpsychism - ancient doctrine - before any records of systematic philosophy. Some form of animism, very closely related to panpsychism, seems to be an almost universal feature of pre-literate societies, and studies of human development suggest that children pass through an animist phase, in which mental states are attributed to a wide variety of objects (Piaget)

15 The Presocratics recognized the basic dilemma: either mind is an elemental feature of the world or it somehow emerges from such features. If one opts for panpsychism then one must account for the apparent total lack of mental features at the fundamental level. If one opts for emergence, what are the means by which new features emerge? the twentieth century witnessed the victory of emergentism

16 emergentism If one believes that the most fundamental physical entities (quarks) are devoid of any mental attributes, and if one also believes that some systems of these entities, such as human brains, do possess mental attributes, one is espousing some kind of doctrine of the emergence of mind. All the currently popular physicalist theories (behaviorism, functionalism) are theories which attempt to provide an account of how the mental emerges from the physical.

17 Ethology: looking at animals

18 Operant conditioning Konorski and Thorndike Law of effect: behaviors followed by satisfying consequences tend to be repeated and those that produce unpleasant consequences are less likely to be repeated Skinner - rejected the reference to unobservable mental states, building his analysis on observable behavior and its equally observable consequences. operant conditioning chamber - subjects were isolated from extraneous stimuli and free to make one or two simple, repeatable responses. extended operant conditioning to language

19 learning Positive reinforcement: when a response is followed by a stimulus that is rewarding, increasing the frequency of that behavior. Example: food delivered when the rat engages in a target behavior, such as pressing a lever. Negative reinforcement: when a behavior is followed by the removal of an aversive stimulus, increasing that behavior's frequency. Example: a loud noise sounding inside the rat's cage until it engages in the target behavior, upon which the noise is removed. Positive punishment: when a behavior is followed by a stimulus, such as introducing a shock, resulting in a decrease in that behavior. Negative punishment: when a behavior is followed by the removal of a stimulus, such as taking away a child's toy following an undesired behavior, resulting in a decrease in that behavior. Extinction: when a behavior that had previously been reinforced is no longer effective. For example, a rat is given food many times for lever presses. Then no food is given. Typically the rat continues to press more and more slowly and eventually stops.

20 Cognitive ethology D. Griffin - over 20 years ago getting scientists to face up to questions about mental states in nonhuman animals Traditionally, cognitive ethologists have questioned research methods that isolate animals in unnatural surroundings and present them with a limited set of artificial stimuli Animals should be studied in their natural environments

21 Some findings PLAN: Apes understand tools and plan their use (Max Planck Institute, Leipzig), 2. CULTURE: Animals follow cultural norms (do a task the same way that others in a group do, even if an alternative method exists - Emory University) 3. GAME: Young animals play make-believe, an activity considered an early sign of linguistic abilities (Georgia State University) 4. SPACE and localization 5. LANGUAGE: animals can learn language - Koko (Stanford University)

22 1 - Planning 22 A metaphor for ape cognition is an Estonian folktale. a young girl dreams of attending a party where she can't eat dessert because she has no spoon. The next night, the girl takes a spoon to bed, in case the dream recurs scientists placed chimpanzee and orangutans in a similar scenario apes would hold on to a tool that they wouldn't need until much later? Apes Save Tools for Future Use by N. J. Mulcahy and J. Call, Leipzig Science, May 2006

23 23 Before the test, the apes learned how to retrieve grapes inside a container by inserting a plastic pipe into a slot. There were 4 objects: a peg, a plastic dish, a bowl, and the slotfitting pipe. Each animal was free to take away an object and to bring it back after a delay. The test was performed 16 times for each animal. On average, each ape solved the task 7 times. The best-performing animals were brought back the day after, yet about half the time they carried the appropriate tool the next morning. the animals' delayed success depends on them making a realization similar to that of the girl in the folktale, who had to fail--at least in her dream--before she could plan ahead?

24 observing Santino 24 Santino in the morning collects stones into his deposit. In the afternoon it throws them to visitors. Many apes throw objects, but the novelty with Santino is that he makes caches of these missiles while he is fully calm and only throws them much later on. Other evidence of planning from apes in the wild. For example, orangutans often give "long calls" to let others know the direction in which they're going to travel a couple hours later. Tthe long calls suggest that apes might at least plan their afternoons.

25 2 - Culture 25 animals conform to cultural influences (Emory University ) two groups of apes learned to operate a device that releases food when a trigger is either lifted or poked. In each group, subordinate apes predominantly got the food in the same way that their group leader did. transmitting knowledge (Duke University). a population of orangutans fashioned sticks to penetrate the husk of a fruit. By contrast, other groups of orangutans risked injury by opening the prickly fruit with their hands. The stick-using orangutans was the only population in which adults foraged together. The apes' frequent interactions enabled less-skilled adults to learn an innovative behavior and teach it to their children.

26 3 Development and play 26 Viki impersonates her adoptive mother. She pushes around the vacuum cleaner, files her fingernails, and smoothes on lipstick with a finger. Though she cannot read, she opens the newspaper every morning and turns the pages one by one, examining some as though she has found an interesting article. If Viki were a child, her parents would say she was pretending. But Viki is a chimpanzee. Pretense and language require ability to use and manipulate symbols (Piaget)

27 pretending 27 Human children demonstrate five stages of pretending, the highest being the treatment of toys as animate objects, which shows up after age 2. researchers analyzed playful interactions between apes and their caregivers. The young apes indeed progressed through the stages of pretend play in the same way that human children do. Bonobo telecontrols a robot (with a bonobo puppet inside) using joystick

28 4 - and language? 28 Koko (gorilla) uses sign language has a vocabulary of over 1000 signs. understands approximately 2,000 words of spoken English. initiates the majority of conversations with her human companions and constructs statements averaging three to six words. Koko has a tested IQ of between 75 and 95 on a human scale, where 100 is considered "normal."

29 all ball 29 When asked, "Do you want to talk about your kitty?" Koko signed, "Cry." "What happened to your kitty?" Koko answered, "Sleep cat." When she saw a picture of a cat who looked very much like AllBall, Koko pointed to the picture and signed, "Cry, sad AllBall, the name given by Koko to her kitten (no tail) (AllBall was then killed by a car)

30 symbols Apes with apps IEEE Spectrum 2012 Kanzi, a 31-year-old bonobo, can converse with humans by selecting lexigram symbols on his Motorola Xoom tablet. He recognizes nearly 500 of these lexigrams, which he uses to make requests, answer questions, and compose short sentences. The spoken words he understands number in the thousands.

31 symbols Apes with apps IEEE Spectrum 2012

32 5 space and localization in animals Bird navigation earth s magnetic field, sun, stars, landmarks. magnetic compass, sun compass, celestial compass. Insect navigation sun compass, pheromones Other animals and man A neural representation of space and direction is found in the hippocampal cells of rats a housecat who got lost on a family excursion, after two months and about 200 miles returned to her hometown in Daytona Beach (Florida).

33 Space and navigation behaviors Kinesis varying the rate of locomotion and frequency of turning in moving toward a signal. a single sensory element connected to a single motor control Taxis movement while orienting the body to a directional cue. a single receptor, a comparator, a short term memory. Homing a round trip. Path integration to measure the distance travelled. a directional sense (compass), an odometer based on optic flow, rotation sensor. Homing involves memory of the environment snapshot of the retina image. Migration long distance travel. a compass, a way to measure distance and time. Some animals may have a map.

34 Psychology - Space Kant - Space is absolute but it is not a property of the physical world; rather it is an innate principle of the mind. Newton - Space is absolute however it is inaccessible to our senses, so we learn a relative psychological space Berkeley - The physical world does not exist apart from minds. Everything is either a sensation produced by the mind, or a sensation impressed on us by God.

35 How do we create space? Piaget: children s understanding of space sensory-motor stage (birth-2) - object permanence: The concept that things continue to exist even when they are out of sight- mental representations preoperational stage (2-7) - use mental representations and language to reason about the world. egocentric: Unable to see things from another person s point of view. concrete operations (7-11)- understand conservation The concept that basic amounts remain constant despite superficial changes in appearances formal operations (11-15) - abstract thought.

36 encoding space and objects with respect to self, egocentric based on motor pattern humans use egocentric map when oriented using metric (distance and direction) information with respect to self ( dead reckoning ) if disrupted use topological information with respect to the environment, geocentric topology metric maps landmarks

37 Manipulate An affordance is often taken as a relation between an object, or an environment, and an organism that affords the opportunity for that organism to perform an action. For example, a knob affords twisting, and perhaps pushing, while a cord affords pulling. As a relation, an affordance exhibits the possibility of some action, and is not a property of either an organism or its environment alone. The term has further evolved for use in the context of human computer interaction to indicate the easy discoverability of possible actions. The word is used in a variety of fields including industrial design and artificial intelligence.

38 Psychological space Space was a way of perceiving, not a thing to be perceived. O Keefe & Nadel, The Hippocampus as a Cognitive Map, the brain forms a cognitive mapping system in the hippocampus that acts as an internal global positioning system. Powering the system are place cells, neurons that use data about distance and directions to pinpoint locations. The road to neuroscience

39 Is the hardware important? Is the hardware relevant? Neuroscience

40 Neuroscience Implementation in the brain Aims: Correlate the activation of brain areas and neurons to activity Tools: Brain imaging single-cell recording animal models lesion studies Most studied: senso-motor system imitation and learning

41 The motor cortex in animals Hip Trunk Arm Hand Motor cortex has different size in different species Very large in rats: complex motion planning is expected Foot Face Tongue Larynx

42 p g pp g y cortex Sensory cortex is paired with motor cortex

43 Sensomotor system The integration of the sensory and motor systems allows animals to take sensory information and use it to make useful motor actions. To produce the desired flexibility the nervous system uses internal models Forward model: the nervous system predicts the new state of the motor apparatus and the sensory stimuli that result from a motion Inverse model: the nervous system estimates either the motor command that caused a change in sensory information or the motor command that will reach the target state

44 Voluntary movements reference input is the target sensory state that the controller (inverse model) will use to compute a motor command. The plant (motor unit) executes the motor command which results in a new sensory state. This state is compared to the state predicted by the forward model to obtain an error signal. This error signal can be used to correct the internal model or the current movement

45 Embodiment 45 Monkey Think, Robot Do (2000 -Duke university) prediction from cortex signals for 2 tasks: follow a visual target, pick up food in four corners

46 Prediction from cortical signals Uses linear and non linear models (ANN) Many proposed applications

47 walking from cortical signals 47 Monkey's Thoughts Makes Robot Walk from Across the Globe Duke university two rhesus monkeys were implanted with electrodes that gathered feedback from cells in the brain's motor and sensory cortex. recorded how the cells responded as the monkey walked on a treadmill at a variety of speeds. sensors on the monkey's legs tracked the actual walking patterns the information gathered from the brain cells was able to predict the exact speed of movement and stride length of the legs. a real-time transmission of information allowed the brain activity of the monkey in North Carolina to control a robot in Japan.

48 48 The most stunning finding is that when we stopped the treadmill and the monkey ceased to move its legs, it was able to sustain the locomotion of the robot for a few minutes just by thinking using only the visual feedback of the robot in Japan

49 Rythmic movements The control of movement in biological motor systems appears to be based on a "bottom-up" approach based upon the integration, sensory-based modulation, and learning of control primitives. central pattern generators (CPGs) in invertebrates and vertebrates - explains how simple and complex repetitive movements are generated as a result of the coordination of multiple patterns. Implemented as neural oscillators in robotics

50 Central pattern generator 50 2 processes interact: each sequentially increases and decreases, and the system returns to the starting condition Half-centered model (Brown 1914)

51 Central Pattern Generators Half-center Model alternating activity in flexor & extensor Walking step-cycle has 2 phases swing phase foot off ground & flexing upward stance phase foot planted & leg extending Each limb has its own pattern generator Sensory feedback is not necessary

52 The lamprey motor system excitatory (EIN) maintain activity by exciting all other cells, contralateral inhibitory interneurons (CIN) suppress contralateral activity, lateral inhibitory interneurons (LIN) terminate ipsilateral activity motoneurons (MN) which provide output to the muscles. An external sensor - edge cell (EC) provides feedback to the neural system and thus allows the network to adjust for external forces

53 Examples Birds Flight can be run on a CPG Humans Can cut spinal cord and a bird can continue in a straight line. Breathing is a CPG University of Lausanne, salamander

54 CPG warugadar 54

55 The other minds problem

56 High level functions High level cognitive processes? Generate new goals

57 Cortex-amygdala-thalamus Cortex patterns, memory Thalamus - maintains a map of the cortex - novelty Amygdala instints and emotions

58 Circuits used in robotics Modelling the reaching behavior (humans) as guided by vision - icub Modelling the capability to map the environment and to move around mobile robots Modelling imitation learning through mirror neurons play

59 Linguistics Phonology Morphology Syntax Semantics Pragmatics

60 Understanding natural language Early hopes for artificial intelligence have not been achieved. A three-year-old child is better able to understand and generate language than any current computer system. Different attemps: syntax+semantics (as in artificial languages) Add deduction (as in theorem provers) Add knowledge (as in Cyc) Use paradigms as agents, case-based, Add embodyment

61 Foundations for Language and Logic Perception action - mental models Meanings expressed in language are based on perception. Thinking and reasoning are based on mental models (that use the same mechanisms as perception and action). mathematics and logic are abstractions from the symbols Computer systems can manipulate those symbols.but computers are much less efficient than humans in perception and action. Language can express logic, but it does not depend on logic Language is situated, embodied, distributed, and dynamic. logics action Think Reason Mental models meaning perception

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63 Ex: recognizing the word fork C: Concept of a fork in the parietal lobe links to all other areas. V: Visual recognition in the temporal lobe links to the visual cortex. T: Tactile feel of a fork in the somatosensory cortex. M: Motor schemata for manipulating a fork in the motor area. PR: Phonology for recognizing the word 'fork' in Wernicke s area. PA: Phonology for the sound /fork/ in the primary auditory cortex. PP: Phonology for producing the articulation of /fork/ in Broca s area.

64 A Brain Trick I cdnuolt blveiee taht I cluod aulaclty uesdnatnrd waht I was rdanieg The phaonmneal pweor of the hmuan mnid Aoccdrnig to a rscheearch at Cmabrigde Uinervtisy, it deosn't mttaer in waht oredr the ltteers in a wrod are, the olny iprmoatnt tihng is taht the frist and lsat ltteer be in the rghit pclae. The rset can be a taotl mses and you can sitll raed it wouthit a porbelm. Tihs is bcuseae the huamn mnid deos not raed ervey lteter by istlef, but the wrod as a wlohe. Amzanig huh? yaeh and I awlyas thought slpeling was ipmorantt.

65 Anthropology Núñez & Sweetser (2006): Analyzed gestures when speaking about events Aymara speakers look towards the past and have future behind their backs Nayra = past (eye, sight, ancestor) Q ipa = future (back, behind) Q ipüru = tomorrow = q ipa + uru (day behind one s back)