Specialization of Perceptual Processes

In this report, I discuss the use of vision to support concrete, everyday activity. I will argue that a variety of interesting tasks can be solved using simple and inexpensive vision systems. I will provide a number of working examples in the form of a state-of-the-art mobile robot, Polly, which uses vision to give primitive tours of the seventh floor of the MIT AI Laboratory. By current standards, the robot has a broad behavioral repertoire and is both simple and inexpensive (the complete robot was built for less than $20,000 using commercial board-level components). The approach I will use will be to treat the structure of the agent's activity---its task and environment---as positive resources for the vision system designer. By performing a careful analysis of task and environment, the designer can determine a broad space of mechanisms which can perform the desired activity. My principal thesis is that for a broad range of activities, the space of applicable mechanisms will be broad enough to include a number mechanisms which are simple and economical. The simplest mechanisms that solve a given problem will typically be quite specialized to that problem. One thus worries that building simple vision systems will be require a great deal of {it ad-hoc} engineering that cannot be transferred to other problems. My second thesis is that specialized systems can be analyzed and understood in a principled manner, one that allows general lessons to be extracted from specialized systems. I will present a general approach to analyzing specialization through the use of transformations that provably improve performance. By demonstrating a sequence of transformations that derive a specialized system from a more general one, we can summarize the specialization of the former in a compact form that makes explicit the additional assumptions that it makes about its environment. The summary can be used to predict the performance of the system in novel environments. Individual transformations can be recycled in the design of future systems

Nonhuman primates as models of hemispheric specialization

The present chapter concerns the issue of hemispheric specialization for perceptual and cognitive processes. In spite of a long-lasting view that only humans are lateralized (e.g., Warren, 1980), there is now strong documentation for anatomical lateralizations, functional lateralizations, or both in several animal taxa, including birds, rodents, and nonhuman primates (see Bradshaw & Rogers, 1993; Hellige, 1993). We selectively report demonstrations from studies of nonhuman primates. After a short review of the evidence for structural (anatomical) lateralization, we describe..

Specialization effect and its influence on memory and problem solving in expert chess players

Expert chess players, specialized in different openings, recalled positions and solved problems within and outside their area of specialization. While their general expertise was at a similar level players performed better with stimuli from their area of specialization. The effect of specialization on both recall and problem solving was strong enough to override general expertise – players remembering positions and solving problems from their area of specialization performed at around the level of players one standard deviation above them in general skill. Their problem solving strategy also changed depending on whether the problem was within their area of specialization or not. When it was, they searched more in depth and less in breadth; with problems outside their area of specialization, the reverse. The knowledge that comes from familiarity with a problem area is more important than general purpose strategies in determining how an expert will tackle it. These results demonstrate the link in experts between problem solving and memory of specific experiences and indicate that the search for context independent general purpose problem solving strategies to teach to future experts is unlikely to be successful

From Stereogram to Surface: How the Brain Sees the World in Depth

When we look at a scene, how do we consciously see surfaces infused with lightness and color at the correct depths? Random Dot Stereograms (RDS) probe how binocular disparity between the two eyes can generate such conscious surface percepts. Dense RDS do so despite the fact that they include multiple false binocular matches. Sparse stereograms do so even across large contrast-free regions with no binocular matches. Stereograms that define occluding and occluded surfaces lead to surface percepts wherein partially occluded textured surfaces are completed behind occluding textured surfaces at a spatial scale much larger than that of the texture elements themselves. Earlier models suggest how the brain detects binocular disparity, but not how RDS generate conscious percepts of 3D surfaces. A neural model predicts how the layered circuits of visual cortex generate these 3D surface percepts using interactions between visual boundary and surface representations that obey complementary computational rules.Air Force Office of Scientific Research (F49620-01-1-0397); National Science Foundation (EIA-01-30851, SBE-0354378); Office of Naval Research (N00014-01-1-0624

Seeing what we know and understand

Expertise in object recognition, as in bird watching or X-ray specialization, is based on extensive perceptual experience and in-depth semantic knowledge. Although it has been shown that rich perceptual experience shapes elementary perception and higher level discrimination and identification, little is known about the influence of in-depth semantic knowledge on object perception and identification. By means of recording event-related brain potentials (ERPs), we show that the amount of knowledge acquired about initially unfamiliar objects modulates visual ERP components already 120 msec after object presentation, and causes gradual variations of activity in similar brain systems within a later timeframe commonly associated with meaning access. When perceptual analysis is made more difficult by blurring object pictures, knowledge has an even stronger effect on perceptual analysis and facilitates recognition. These findings demonstrate that in-depth knowledge not only affects involuntary semantic memory access, but also shapes perception by penetrating early visual processes traditionally held to be immune to such influences.Peer Reviewe

The Complementary Brain: A Unifying View of Brain Specialization and Modularity

Defense Advanced Research Projects Agency and Office of Naval Research (N00014-95-I-0409); National Science Foundation (ITI-97-20333); Office of Naval Research (N00014-95-I-0657

Precis of neuroconstructivism: how the brain constructs cognition

Neuroconstructivism: How the Brain Constructs Cognition proposes a unifying framework for the study of cognitive development that brings together (1) constructivism (which views development as the progressive elaboration of increasingly complex structures), (2) cognitive neuroscience (which aims to understand the neural mechanisms underlying behavior), and (3) computational modeling (which proposes formal and explicit specifications of information processing). The guiding principle of our approach is context dependence, within and (in contrast to Marr [1982]) between levels of organization. We propose that three mechanisms guide the emergence of representations: competition, cooperation, and chronotopy; which themselves allow for two central processes: proactivity and progressive specialization. We suggest that the main outcome of development is partial representations, distributed across distinct functional circuits. This framework is derived by examining development at the level of single neurons, brain systems, and whole organisms. We use the terms encellment, embrainment, and embodiment to describe the higher-level contextual influences that act at each of these levels of organization. To illustrate these mechanisms in operation we provide case studies in early visual perception, infant habituation, phonological development, and object representations in infancy. Three further case studies are concerned with interactions between levels of explanation: social development, atypical development and within that, developmental dyslexia. We conclude that cognitive development arises from a dynamic, contextual change in embodied neural structures leading to partial representations across multiple brain regions and timescales, in response to proactively specified physical and social environment

Physiological responses to verbally inaccessible pictorial information in the left and right hemispheres. Neuropsychology

We investigated the effects of very brief pictorial information on transfer between the cerebral hemispheres through recordings of skin conductance responses. The pictorial stimuli had been judged previously as "neutral", "positive", or "negative" by an independent group of subjects. The verbally-available stimuli (VA) were neutral whereas the very brief, verbally-unavailable stimuli (VU) were positive or negative. The VA and VU stimuli were presented simultaneously, either in the same visual half-field (intra-hemispheric interference) or in the opposite visual half-field (inter-hemispheric interference). In a third condition, there were only VA stimuli in either visual field (no interference). We found that the right hemisphere was especially sensitive to negative VU presentations, both in the inter-and intra-hemispheric interference groups. The left hemisphere showed a corresponding sensitivity to positive interference, but only in the inter-hemispheric interference group. These findings confirm the hemispheric roles in mediating positive versus negative emotions and they show that in the interplay between hemispheric specialization and commissural transfer, left to right transfer can take place without linguistic cognition

Planning Curricular Proposals on Sound and Music with Prospective Secondary-School Teachers

Sound is a preferred context to build foundations on wave phenomena, one of the most important disciplinary referents in physics. It is also one of the best-set frameworks to achieve transversality, overcoming scholastic level and activating emotional aspects which are naturally connected with every day life, as well as with music and perception. Looking at sound and music by a transversal perspective - a border-line approach between science and art, is the adopted statement for a teaching proposal using meta-cognition as a strategy in scientific education. This work analyzes curricular proposals on musical acoustics, planned by prospective secondary-school teachers in the framework of a Formative Intervention Module answering the expectation of making more effective teaching scientific subjects by improving creative capabilities, as well as leading to build logical and scientific categorizations able to consciously discipline artistic activity in music students. With this aim, a particular emphasis is given to those concepts - like sound parameters and structural elements of a musical piece, which are best fitted to be addressed on a transversal perspective, involving simultaneously physics, psychophysics and music.Comment: 12 pages with 5 figures. Submitted for publication in Physics Curriculum Design, Development and Validation - GIREP 2008 book of selected papers, 200