Showing papers by "James L. McClelland published in 2010"

Integration of Sensory and Reward Information during Perceptual Decision-Making in Lateral Intraparietal Cortex (LIP) of the Macaque Monkey

Abstract: Single neurons in cortical area LIP are known to carry information relevant to both sensory and value-based decisions that are reported by eye movements. It is not known, however, how sensory and value information are combined in LIP when individual decisions must be based on a combination of these variables. To investigate this issue, we conducted behavioral and electrophysiological experiments in rhesus monkeys during performance of a two-alternative, forced-choice discrimination of motion direction (sensory component). Monkeys reported each decision by making an eye movement to one of two visual targets associated with the two possible directions of motion. We introduced choice biases to the monkeys' decision process (value component) by randomly interleaving balanced reward conditions (equal reward value for the two choices) with unbalanced conditions (one alternative worth twice as much as the other). The monkeys' behavior, as well as that of most LIP neurons, reflected the influence of all relevant variables: the strength of the sensory information, the value of the target in the neuron's response field, and the value of the target outside the response field. Overall, detailed analysis and computer simulation reveal that our data are consistent with a two-stage drift diffusion model proposed by Diederich and Bussmeyer [1] for the effect of payoffs in the context of sensory discrimination tasks. Initial processing of payoff information strongly influences the starting point for the accumulation of sensory evidence, while exerting little if any effect on the rate of accumulation of sensory evidence.

Emergence in cognitive science.

Abstract: The study of human intelligence was once dominated by symbolic approaches, but over the last 30 years an alternative approach has arisen. Symbols and processes that operate on them are often seen today as approximate characterizations of the emergent consequences of sub- or nonsymbolic processes, and a wide range of constructs in cognitive science can be understood as emergents. These include representational constructs (units, structures, rules), architectural constructs (central executive, declarative memory), and developmental processes and outcomes (stages, sensitive periods, neurocognitive modules, developmental disorders). The greatest achievements of human cognition may be largely emergent phenomena. It remains a challenge for the future to learn more about how these greatest achievements arise and to emulate them in artificial systems.

Locating object knowledge in the brain: comment on Bowers's (2009) attempt to revive the grandmother cell hypothesis.

Abstract: According to Bowers (2009), the finding that there are neurons with highly selective responses to familiar stimuli supports theories positing localist representations over approaches positing the type of distributed representations typically found in parallel distributed processing (PDP) models. However, his conclusions derive from an overly narrow view of the range of possible distributed representations and of the role that PDP models can play in exploring their properties. Although it is true that current distributed theories face challenges in accounting for both neural and behavioral data, the proposed localist account—to the extent that it is articulated at all—runs into more fundamental difficulties. Central to these difficulties is the problem of specifying the set of entities a localist unit represents.

The memory process : neuroscientific and humanistic perspectives

Abstract: The Memory Process offers a groundbreaking, interdisciplinary approach to the understanding of human memory, with contributions from both neuroscientists and humanists The first book to link the neuroscientific study of memory to the investigation of memory in the humanities, it connects the latest findings in memory research with insights from philosophy, literature, theater, art, music, and film Chapters from the scientific perspective discuss both fundamental concepts and ongoing debates from genetic and epigenetic approaches, functional neuroimaging, connectionist modeling, dream analysis, and neurocognitive studies The humanist analyses offer insights about memory from outside the laboratory: a taxonomy of memory gleaned from modernist authors including Virginia Woolf, James Joyce, and William Faulkner; the organization of memory, seen in drama ranging from Hamlet to The Glass Menagerie; procedural memory and emotional memory in responses to visual art; music's dependence on the listener's recall; and the vivid renderings of memory and forgetting in such films as Memento and Eternal Sunshine of the Spotless Mind The chapters from the philosophical perspective serve as the bridge between science and the arts The volume's sweeping introduction offers an integrative merging of neuroscientific and humanistic findings Contributors: John Bickle, Jean-Pierre Changeux, Valerie Doyere, Yadin Dudai, Atillio Favorini, John Burt Foster, David Freedberg, Walter Glannon, Robert Stickgold, David Hertz, William Hirstein, Joseph LeDoux, Paul Matthews, James L McClelland, Suzanne Nalbantian, Isabelle Peretz, Alan Richardson, Edmund Rolls, Severine Samson, Alcino Silva, Barbara Tillmann, Fernando Vidal

Complementary processing systems: A PDP model of the simultaneous perception of multiple objects

Abstract: Complementary processing systems: A PDP model of the simultaneous perception of multiple objects Cynthia Henderson Stanford University James McClelland Stanford University Abstract: Illusory conjunctions in normal and simultanagnosic subjects are instances where the binding of visual information fails to function correctly. When presented with multiple objects simultaneously, simultanagnosic pa- tients and normal subjects under conditions of attentional loads or brief presentation times often erroneously report miscombinations of features of the objects. A connectionist model of multi-object perception examines how the concurrent perception of more than one object could occur in normal subjects and become deficient with shortened processing times. In this model, the correct identification of two objects is accomplished through lateral connections between the ventral and dorsal pathways. Lesioning of the dorsal pathway produces failures in multi-object recogni- tion characteristic of the effect of parietal damage in simultanagnosia. It is hoped that the functioning of this model might help elucidate possible processes underlying the correct solution of the binding problem in normal subjects.

Matching Exact Posterior Probabilities in the Multinomial Interactive Activation Model

Abstract: Matching Exact Posterior Probabilities in the Multinomial Interactive Activation Model Pranav Khaitan Stanford University James L McClelland Stanford University Abstract: Interactive activation models of context effects in perception ((McClelland & Rumelhart, 1981; McClel- land & Elman, 1986) have been criticized for failing to combine stimulus and context information in a Bayes-optimal way, leading to a rejection of interactive approaches (Norris & McQueen, 2008) We show that interactive activation can compute correct Bayesian posterior probabilities We present a variant of the interactive activation model that produces outputs exactly corresponding to the correct posterior probabilities of letters given specified letter feature and context information In the new variant of the model, inhibition between units within pools is replaced by selection of a single unit to be active, using the softmax function to assign probabilities to candidate alternatives The model is fully interactive, yet the probability of a letter unit being activated is both provably and demonstrably equal to the posterior probability given the presented feature and context information