Marius Usher - Academia.edu (original) (raw)

Papers by Marius Usher

1. did not incorporate mechanisms proposed to explain set size effects in J. D. Cohen, K. Dunb... more 1998) did not incorporate mechanisms proposed to explain set size effects in J. D. Cohen, K. Dunbar, and J. L. . The authors report a new simulation that incorporates these mechanisms and more accurately simulates S. M. Kanne et al.'s empirical data. The authors then point to other factors that could be explored in a more complete test of their model. The use of feed-forward rather than recurrent inhibition is discussed as a potentially important limitation of their original model, and recent work addressing this issue is described. The authors also discuss possible differences between word reading and color naming in the Stroop task. Although such differences may exist, the authors retain their earlier view that such differences do not reflect a dichotomy between automatic and controlled processing.

Journal of Philosophy, 2006

Personality and Individual Differences, 2009

... Additional schizotypy research may also contrast between tasks that tap on language lateraliz... more ... Additional schizotypy research may also contrast between tasks that tap on language lateralization and tasks that tap on other cognitive processes that are deficient in schizophrenia and are associated with the frontal cortex (Cohen & Servan-Schreiber, 1992). ...

Connectionist Models of Neurocognition and Emergent Behavior, 2011

Psychological Review, 2015

Trueblood, Brown, and Heathcote (2014) provide a new model of multiattribute choice, which accoun... more Trueblood, Brown, and Heathcote (2014) provide a new model of multiattribute choice, which accounts for 3 contextual reversal effects (similarity, attraction and compromise). We review the details of the model and highlight some novel predictions. First, we show that the model works by setting a "fine balance" between 2 opposing factors that influence choice. As a result, small changes in the attributes of choice alternatives can disturb this balance. Second, we show that the model gives a partial account of the compromise effect. We describe a number of experiments that could distinguish the MLBA from other models of multiattribute choice. (PsycINFO Database Record

Prospects for Bayesian cognitive science, 2008

Connectionist Models of Cognition, Perception and Emotion - Proceedings of the Eighth Neural Computation and Psychology Workshop, 2004

In previous work, we developed a neurocomputational model of list memory, based on neural mechani... more In previous work, we developed a neurocomputational model of list memory, based on neural mechanisms, such as recurrent self-excitation and global inhibition that implement a short-term memory activation-buffer. Here, we compare this activationbuffer with a series of mathematical buffer models that originate from the 1960s, with special emphasis on presentation rate effects. We then propose an extension of the activation-buffer to address the process of selectively updating the buffer contents, which is critical for modeling working memory and complex higher-level cognition.

Connectionist Models of Cognition and Perception - Proceedings of the Seventh Neural Computation and Psychology Workshop, 2002

We present an activation-based computational model of immediate item memory, which is proposed to... more We present an activation-based computational model of immediate item memory, which is proposed to underlie activation based processes within the pre-frontal cortex (mediating primary memory) that trigger episodic learning processes in the medial temporal cortex (secondary memory). We show that the model is able to capture a range of basic phenomena such as Brown-Peterson forgetting functions and serial position functions in cued and freerecall. The model makes unique predictions for presentation rate and list length effects, which were tested (and supported) in subsequent experiments.

Scientific Reports, 2015

We investigated the mechanism with which humans estimate numerical averages. Participants were pr... more We investigated the mechanism with which humans estimate numerical averages. Participants were presented with 4, 8 or 16 (two-digit) numbers, serially and rapidly (2 numerals/second) and were instructed to convey the sequence average. As predicted by a dual, but not a single-component account, we found a non-monotonic influence of set-size on accuracy. Moreover, we observed a marked decrease in RT as set-size increases and RT-accuracy tradeoff in the 4-, but not in the 16-number condition. These results indicate that in accordance with the normative directive, participants spontaneously employ analytic/sequential thinking in the 4-number condition and intuitive/holistic thinking in the 16-number condition. When the presentation rate is extreme (10 items/sec) we find that, while performance still remains high, the estimations are now based on intuitive processing. The results are accounted for by a computational model postulating population-coding underlying intuitive-averaging and working-memory-mediated symbolic procedures underlying analytical-averaging, with flexible allocation between the two.

Psychonomic Bulletin & Review, 2015

Making decisions based on relative rather than absolute information processing is tied to choice ... more Making decisions based on relative rather than absolute information processing is tied to choice optimality via the accumulation of evidence differences, and to canonical neural processing via accumulation of evidence ratios. These theoretical frameworks predict invariance of decision latencies to absolute intensities that maintain differences and ratios, respectively. While information about the absolute values of the choice alternatives is not necessary for choosing the best alternative, it may nevertheless hold valuable information about the context of the decision.

Frontiers in human neuroscience, 2014

Evidence from neuropsychology and neuroimaging indicate that the pre-frontal cortex (PFC) plays a... more Evidence from neuropsychology and neuroimaging indicate that the pre-frontal cortex (PFC) plays an important role in human memory. Although frontal patients are able to form new memories, these memories appear qualitatively different from those of controls by lacking distinctiveness. Neuroimaging studies of memory indicate activation in the PFC under deep encoding conditions, and under conditions of semantic elaboration. Based on these results, we hypothesize that the PFC enhances memory by extracting differences and commonalities in the studied material. To test this hypothesis, we carried out an experimental investigation to test the relationship between the PFC-dependent factors and semantic factors associated with common and specific features of words. These experiments were performed using Free-Recall of word lists with healthy adults, exploiting the correlation between PFC function and fluid intelligence. As predicted, a correlation was found between fluid intelligence and the...

Physical review. A, Jan 15, 1989

We incorporate local threshold functions into the dynamics of the Hopfield model. These functions... more We incorporate local threshold functions into the dynamics of the Hopfield model. These functions depend on the history of the individual spin (= neuron). They reach a maximal height if the spin remains constant. The resulting one-pattern model has ferromagnetic, paramagnetic, and periodic phases. This model is solved by a master equation and approximated by simplified systems of equations that

Advances in Pharmacology, 1997

1. did not incorporate mechanisms proposed to explain set size effects in J. D. Cohen, K. Dunb... more 1998) did not incorporate mechanisms proposed to explain set size effects in J. D. Cohen, K. Dunbar, and J. L. . The authors report a new simulation that incorporates these mechanisms and more accurately simulates S. M. Kanne et al.'s empirical data. The authors then point to other factors that could be explored in a more complete test of their model. The use of feed-forward rather than recurrent inhibition is discussed as a potentially important limitation of their original model, and recent work addressing this issue is described. The authors also discuss possible differences between word reading and color naming in the Stroop task. Although such differences may exist, the authors retain their earlier view that such differences do not reflect a dichotomy between automatic and controlled processing.

Journal of Philosophy, 2006

Personality and Individual Differences, 2009

... Additional schizotypy research may also contrast between tasks that tap on language lateraliz... more ... Additional schizotypy research may also contrast between tasks that tap on language lateralization and tasks that tap on other cognitive processes that are deficient in schizophrenia and are associated with the frontal cortex (Cohen & Servan-Schreiber, 1992). ...

Connectionist Models of Neurocognition and Emergent Behavior, 2011

Psychological Review, 2015

Trueblood, Brown, and Heathcote (2014) provide a new model of multiattribute choice, which accoun... more Trueblood, Brown, and Heathcote (2014) provide a new model of multiattribute choice, which accounts for 3 contextual reversal effects (similarity, attraction and compromise). We review the details of the model and highlight some novel predictions. First, we show that the model works by setting a "fine balance" between 2 opposing factors that influence choice. As a result, small changes in the attributes of choice alternatives can disturb this balance. Second, we show that the model gives a partial account of the compromise effect. We describe a number of experiments that could distinguish the MLBA from other models of multiattribute choice. (PsycINFO Database Record

Prospects for Bayesian cognitive science, 2008

Connectionist Models of Cognition, Perception and Emotion - Proceedings of the Eighth Neural Computation and Psychology Workshop, 2004

In previous work, we developed a neurocomputational model of list memory, based on neural mechani... more In previous work, we developed a neurocomputational model of list memory, based on neural mechanisms, such as recurrent self-excitation and global inhibition that implement a short-term memory activation-buffer. Here, we compare this activationbuffer with a series of mathematical buffer models that originate from the 1960s, with special emphasis on presentation rate effects. We then propose an extension of the activation-buffer to address the process of selectively updating the buffer contents, which is critical for modeling working memory and complex higher-level cognition.

Connectionist Models of Cognition and Perception - Proceedings of the Seventh Neural Computation and Psychology Workshop, 2002

We present an activation-based computational model of immediate item memory, which is proposed to... more We present an activation-based computational model of immediate item memory, which is proposed to underlie activation based processes within the pre-frontal cortex (mediating primary memory) that trigger episodic learning processes in the medial temporal cortex (secondary memory). We show that the model is able to capture a range of basic phenomena such as Brown-Peterson forgetting functions and serial position functions in cued and freerecall. The model makes unique predictions for presentation rate and list length effects, which were tested (and supported) in subsequent experiments.

Scientific Reports, 2015

We investigated the mechanism with which humans estimate numerical averages. Participants were pr... more We investigated the mechanism with which humans estimate numerical averages. Participants were presented with 4, 8 or 16 (two-digit) numbers, serially and rapidly (2 numerals/second) and were instructed to convey the sequence average. As predicted by a dual, but not a single-component account, we found a non-monotonic influence of set-size on accuracy. Moreover, we observed a marked decrease in RT as set-size increases and RT-accuracy tradeoff in the 4-, but not in the 16-number condition. These results indicate that in accordance with the normative directive, participants spontaneously employ analytic/sequential thinking in the 4-number condition and intuitive/holistic thinking in the 16-number condition. When the presentation rate is extreme (10 items/sec) we find that, while performance still remains high, the estimations are now based on intuitive processing. The results are accounted for by a computational model postulating population-coding underlying intuitive-averaging and working-memory-mediated symbolic procedures underlying analytical-averaging, with flexible allocation between the two.

Psychonomic Bulletin & Review, 2015

Making decisions based on relative rather than absolute information processing is tied to choice ... more Making decisions based on relative rather than absolute information processing is tied to choice optimality via the accumulation of evidence differences, and to canonical neural processing via accumulation of evidence ratios. These theoretical frameworks predict invariance of decision latencies to absolute intensities that maintain differences and ratios, respectively. While information about the absolute values of the choice alternatives is not necessary for choosing the best alternative, it may nevertheless hold valuable information about the context of the decision.

Frontiers in human neuroscience, 2014

Evidence from neuropsychology and neuroimaging indicate that the pre-frontal cortex (PFC) plays a... more Evidence from neuropsychology and neuroimaging indicate that the pre-frontal cortex (PFC) plays an important role in human memory. Although frontal patients are able to form new memories, these memories appear qualitatively different from those of controls by lacking distinctiveness. Neuroimaging studies of memory indicate activation in the PFC under deep encoding conditions, and under conditions of semantic elaboration. Based on these results, we hypothesize that the PFC enhances memory by extracting differences and commonalities in the studied material. To test this hypothesis, we carried out an experimental investigation to test the relationship between the PFC-dependent factors and semantic factors associated with common and specific features of words. These experiments were performed using Free-Recall of word lists with healthy adults, exploiting the correlation between PFC function and fluid intelligence. As predicted, a correlation was found between fluid intelligence and the...

Physical review. A, Jan 15, 1989

We incorporate local threshold functions into the dynamics of the Hopfield model. These functions... more We incorporate local threshold functions into the dynamics of the Hopfield model. These functions depend on the history of the individual spin (= neuron). They reach a maximal height if the spin remains constant. The resulting one-pattern model has ferromagnetic, paramagnetic, and periodic phases. This model is solved by a master equation and approximated by simplified systems of equations that

Advances in Pharmacology, 1997