University Relations

Fall 2010 Cognitive Science Colloquia

Thursdays, 4:00 - 5:30pm, Elliott Hall N119


September 16

photo of Cheryl Olman"What does V1 have to do with perception?"
Cheryl Olman, Assistant Professor,
Departments of Psychology and Radiology

Primary visual cortex (V1) has the distinction of being the cortical area for which we have the most complete characterization of neural response properties – we know a great deal about both individual neuron tuning functions and the relative spatial organization and interconnectivities of neurons tuned to different visual features. Six decades of electrophysiological investigations have taught us that each V1 neuron is sensitive to only a limited region of the visual field; a useful model of V1 is of an over-complete wavelet-based filter set that decomposes images into local features that can be passed efficiently to higher visual areas for scene segmentation and object recognition. However, in the last 10 years, many fMRI studies have shown that the blood flow response in V1 can be modulated by changes in perceptual state or global scene organization – image properties and cognitive states generally considered to be beyond the purview of V1. Complicating these discoveries is the fact that single-unit studies in primates performing similar perceptual tasks often find very limited, if any, modulation of V1 by perceptual state changes or global scene structure. While there are many theoretical reasons that feedback from higher visual areas should modulate V1 responses in order to improve visual performance for a given task, testing these theories and delineating the neural mechanisms by which V1 neural responses are modulated requires high-resolution measurement of neural responses throughout multiple cortical areas; unfortunately, high-resolution and large field-of-view are generally incompatible imaging goals. However, high-field fMRI offers us this opportunity. I will present results of a recent study using sub-millimeter resolution to characterize perceptual modulation of V1 responses at different cortical depths, one technique that adds a new dimension to our study of the role of V1 in perception.

Suggested reading: Maier, A., Wilke, M., Aura, C., Zhu, C., Ye, F. Q., & Leopold, D. A. (2008). Divergence of fMRI and neural signals in V1 during perceptual suppression in the awake monkey. Nature Neuroscience, 11(10), 1193.


September 23

photo of Andrew Oxenham“Neural coding and perception of pitch: Implications for speech and music”

Andrew L. Oxenham, Professor,
Department of Psychology

Pitch - the perceptual correlate of acoustic periodicity - plays an important role in music, speech, and acoustic communication in general. Despite over a century of empirical and theoretical study, much about how pitch is coded in the auditory system remains in dispute. This talk will provide an overview of what we know and don't know about pitch perception, and will describe some recent studies designed to shed further light on the basic mechanisms as well as their implications for speech and music perception in normal and impaired hearing.

Reference for background reading: Oxenham, A. J. (2008). Pitch perception and auditory stream segregation: Implications for hearing loss and cochlear implants Trends in Amplification 12, 316-331.


September 30

photo of Dr. GeorgopoulosApostolos P. Georgopoulos
Director, Center for Cognitive Sciences
"Neuroprosthetics, Neuromarkers and Cognition: Common Threads in Brain Information Processing"


October 7

photo of Paul SchraterPaul Schrater Assistant Professor, Psychology & Computer Science
"Rational control of aspiration in learning"

How much to explore in an unknown environment is controlled by the agent’s beliefs about the value of unexperienced states, which we refer to as the agent’s “aspiration.” To examine the effect of aspiration on exploratory behavior in humans, we conducted a series of experiments that explore whether prior beliefs and inferences about the reward potential of the environment controls investment in exploratory behavior. We show that prior beliefs about the generative model for the environment can account for individual differences in exploration, that statistical information about reward magnitudes modifies exploration, and that knowledge that other's reward experience exceeds their own creates a complete reinitialization of exploration. Theoretically, we have developed a hierarchical model-based Bayesian reinforcement-learning framework that can mimic all of these behaviors by manipulating the agent’s initial prior belief about the size of the state space and/or the magnitude of potential rewards.


October 14

Jacqueline M. Fulvio

"Human observers maximize their individual potential when selecting extrapolation strategies"

It is not uncommon in nature for distinctive strategies to emerge from differences in ability (e.g. distinctive mating strategies for lizards based on physical size), however, this idea has never been expressed or tested in human visual perception. I will present work on visual extrapolation through occlusion, which requires observers to predict the path of a moving object once it has disappeared behind another object. I will first discuss the role of perceptual ability on predictive performance. I will demonstrate that individuals with different perceptual abilities can be statistically better off using distinctive strategies that trade off bias and variance when these abilities are taken into account, and I will provide compelling evidence that this trade-off does occur in human data. I will then discuss the role of experience on extrapolation performance and provide statistical evidence that the nature of task training and exposure changes how well an individual can be expected to perform. I will present data from human participants who were trained under different conditions that show the predicted performance discrepancies. I will conclude with a general discussion about the implications of these findings for current theory and future work.


October 21

photo of Zeb Kurth-NelsonZeb Kurth-Nelson
"Effects of contingency representation on decision making"

We perform computational simulations of decision making under varying contingency beliefs. The contingency beliefs of the agent are represented as state spaces, where discrete situations are classified as states, and the states are linked by transitions describing how one situation leads to another. We characterize how different state spaces result in different patterns of decision making. In particular, a simple change of representation, without changing the actual contingencies of the world, can cause a switch from addictive to non-addictive behavior. These results raise the possibility that addiction (and other disorders of choice) may be treatable by training general cognitive skills or by influencing the construction of contingency representations. Conversely, drugs may exert addictiveness partly by pharmacologically disrupting the construction of healthy state spaces.


Nov 4

photo of Megan GunnarMegan R. Gunnar Professor, College of Education + Human Development
"Early Experience and Neurobehavioral Development: Studies of Children Adopted Internationally from Orphanages"

Studies of orphanage-reared infants and toddlers have long figured prominently in the arguments about the importance (or not) of early experiences. Studies in the mid-20th Century on the impacts of early institutional rearing led to the closing of institutions in most western industrialized nations in favor of foster care for young children without permanent parents. The easing of the cold war and opening of the former Soviet Republics and China to international adoption has led to a new wave of research on early institutional care and neurobehavioral developing. This lecture will overview key findings from this new wave of research with a specific focus on the neurobiological correlates of the types of cognitive and socioemotional problems observed in children who spend their first months and years in institutional care.


Nov. 11 

photo of Susan Gelman,  University of MichiganSusan Gelman University of Michigan

"Sharks attack humans, but most sharks don't attack humans: Learning to express generalizations in language"

My talk will examine the challenges that learners face when learning to express general categories (e.g., "sharks" in "Sharks attack humans"). These expressions, known as "generics", are both conceptually and linguistically challenging. Although we experience the world in terms of individual objects and events, we must form abstractions that extend beyond these individual entities. Moreover, the same forms of language that are used to express generics are also used to refer to particular individuals (compare "The dog is a 4-legged animal" to "The dog is sleeping"). I discuss different kinds of learning models, and suggest that generics are a default mode of generalization for human learners.


...and at 12:00pm in ICD 105

"Essentialist reasoning in young children"

Essentialism is the idea that items have an underlying reality that explains their manifest appearance and determines their identity. I argue that essentialism is an early cognitive bias. Young children's concepts reflect a deep commitment to essentialism, and this commitment leads children to look beyond the obvious in many converging ways: when learning words, generalizing knowledge to new category members, reasoning about the insides of things, contemplating the role of nature versus nurture, and constructing causal explanations. I also discuss competing theories for why children show essentialist effects, and argue that essentialism is the outcome of several domain-general cognitive processes.


Nov. 18  

photo of Michael WilsonMichael Wilson, Anthropology  and Ecology, Evolution  and Behavior 

"Hunting and fighting in chimpanzees, bonobos and humans: Is coalitionary killing a byproduct of selection for within-group competition for mates?"

Humans have two closest living relatives among the apes: chimpanzees and bonobos. Chimpanzees live across a vast expanse of tropical Africa and have been studied intensively in the wild for 50 years. Bonobos live only in the Democratic Republic of Congo, where civil war has interrupted the few long-term research efforts.  Humans, chimpanzees, and bonobos share many characteristics in common: all three species live in fission-fusion communities, in which males defend group territories and females disperse to new groups at sexual maturity. Bonobos differ strikingly from both humans and chimpanzees, however, in that they apparently lack coalitionary killing, either of prey species or their own species.

The lack of both hunting and conspecific killing in bonobos is interesting, in that for chimpanzees, hunting and conspecific killing share many similar behavioral patterns and ecological correlates. Hunting and conspecific killing are also interesting in that neither behavior appears essential for chimpanzee survival; meat provides only a small proportion of the chimpanzee diet, and many species manage to defend territories by driving their enemies away rather than killing them. Debate continues as to whether bonobos lack coalitionary killing because of selection specifically against coalitionary killing, or as a byproduct of selection for a general reduction in aggressiveness. Arguments for selection specifically against coalitionary killing have focused on feeding ecology and party size, in which bonobos are proposed to travel in larger, more cohesive parties than chimpanzees, creating fewer opportunities for lethal raiding and therefore reduced selection for coalitionary killing.

Subsequent studies, however, have failed to find substantial differences in party composition between the two species. The contrasting hypothesis proposes that coalitionary killing is a byproduct of selection for aspects of male psychology that promote successful competition in other arenas, particularly competition for mates. The strikingly different patterns of female sexual behavior in bonobos and chimpanzees favor strikingly different male strategies for obtaining mating success. In this view, male chimpanzees cooperate to kill because selection has favored males who are not only highly assertive and risk tolerant, but also able to cooperate with other males: traits that turn out to be useful for hunting and killing conspecifics as well. Males compete for mates almost every day, whereas males interact with rival groups much less frequently. While both intra-group and inter-group competition are important, intragroup competition seems likely to provide the stronger selection pressure shaping male psychology. The implications for humans, who have a strikingly different mating system, will be discussed.

Dec. 2    

photo of John SoechtingJohn Soechting, Neuroscience
"Predicting motion in smooth pursuit: extrapolation and cognition"

Part of the talk will be based on a recent paper in PLoSONE: 5(9): e12574, 2010

A predictive component can contribute to the command signal for smooth pursuit. This is readily demonstrated by the fact that low frequency sinusoidal target motion can be tracked with zero time delay or even with a small lead. The objective of this study was to characterize the predictive contributions to pursuit tracking more precisely by developing analytical models for predictive smooth pursuit. Subjects tracked a small target moving in two dimensions. In the simplest case, the periodic target motion was composed of the sums of two sinusoidal motions (SS), along both the horizontal and the vertical axes. Motions following the same or similar paths, but having a richer spectral composition, were produced by having the target follow the same path but at a constant speed (CS), and by combining the horizontal SS velocity with the vertical CS velocity and vice versa. Several different quantitative models were evaluated. The predictive contribution to the eye tracking command signal could be modeled as a low-pass filtered target acceleration signal with a time delay. This predictive signal, when combined with retinal image velocity at the same time delay, as in classical models for the initiation of pursuit, gave a good fit to the data. The weighting of the predictive acceleration component was different in different experimental conditions, being largest when target motion was simplest, following the SS velocity profiles.

The second half is not yet published:
It is well known that prediction is used to overcome processing delays within the motor system and ocular control is no exception. Motion extrapolation is one mechanism that can be used to overcome the visual processing delay. Expectations based on previous experience or cognitive cues are also capable of overcoming this delay. The present experiment was designed to examine how smooth pursuit is altered by cognitive information about the time and/or direction of an upcoming change in target direction. Subjects visually tracked a cursor as it moved at a constant velocity on a computer screen. The target initially moved from left to right and then abruptly reversed horizontal direction and traveled along one of seven possible oblique paths. In half of the trials, a cue was present throughout the trial to signal the position, and thus the time, and/or the direction of the upcoming change. Whenever a timing cue was present, there were clear anticipatory adjustments to the horizontal velocity component of smooth pursuit. In the presence of a timing cue, a directional cue also led to anticipatory adjustments in the vertical velocity, and hence the direction of smooth pursuit. However, without the timing cue, a directional cue alone produced no anticipation. Thus in this task, a cognitive spatial cue about the new direction could not be used unless it was made explicit in the time domain.


Dec. 9    

photo of Ida ToivenenIda Toivonen Carleton University, Ottawa, Canada

"The role of duration in sound systems"

The sound systems of natural languages employ a variety of techniques to signal linguistically relevant distinctions. For example, the voicing of the first sound of "bat" distinguishes the word from "pat". This talk focuses on the use of duration in sounds and syllables. Many languages (perhaps most languages) make use of duration in some way in their sound systems. For example, in English, vowels before voiced consonants are longer than vowels before voiceless consonants. This is said to provide an additional cue to a distinction that is otherwise not very salient. In other languages, duration alone marks the difference between words. In Italian, for example duration is distinctive: fatto (fact) and fato (fate) differ in segment duration. The present paper discusses duration in two typologically distinct languages: Inari Saami and Swedish. The two languages both make use of duration, but their quantity systems are reported as radically different. The paper will present results from new data collected from the two languages.


  • Bye, Patrik, Elin Sagulin, Ida Toivonen. 2009. Phonetic duration, phonological quantity and prosodic structure in Inari Saami. Phonetica 66 (4): 199--121.
  • Collinder, Björn. 1952. Three degrees of quantity. Studia Linguistica 5: 28-43.
  • Sapir, Edward. 1933.The psychological reality of phonemes. Published originally in French under the title "La Realité psychologique des phonemes, Journal de Psychologie Normale et Pathologique, 30: 247-265. Reprinted in: Sapir Edward. 1949b [1985].Selected Writings in Language, Culture, and Personality ed. and with new foreword by David G. Mandelbaum, epilogue by Dell Hymes. Berkeley and Los Angeles: University of California Press. First paperback edition 1985.