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Marius usher

Tel Aviv University, School of Psychological Sciences, Faculty Member

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I am Professor of Psychology at the Tel-Aviv University (School of Psychology and Sagol School of Neuroscience) and a researcher in the field of cognitive neuroscience. My research interests are: decision-making and numerical processing (the algorithm the mind/brain uses to generate preferences and make decisions

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Cees van Leeuwen

KU Leuven

Javad Salehi Fadardi

Ferdowsi University of Mashhad

Merav Ben-Nathan

Marta Jankowska

University of Warsaw

Deiniol Skillicorn

Andrey Nikolaev

KU Leuven

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Papers by Marius usher

S2.0 S1053810024001508 main

Consciousness and Coggnition, 2024

A fundamental question in the domain of affect and conscious perception is whether the former can... more A fundamental question in the domain of affect and conscious perception is whether the former can impact the latter. Traditionally, perception and affect were conceived as largely independent. Against this backdrop, it was recently argued that the affective valence of a stimulus can modulate the perceptual experience of its sensory features. An alternative hypothesis is that perceptual experiences have a valenced aspect over and above their sensory aspects, with these two aspects interacting and comprising integral perceptual dimensions. To test this, we carried out two experiments deploying Wendell Garner’s speeded classification paradigm to decide whether visual brightness and affective valence are separable or integral dimensions. We found Garner interference, documenting that brightness and valence are integral dimensions. We did not observe effects of congruity – responses to bright positive stimuli were not faster than to bright negative stimuli — providing no support for affect induced changes in the perception of brightness.

Evidence integration and decision confidence are modulated by stimulus consistency

Nature Human Behaviour, 2022

Evidence integration is a normative algorithm for choosing between alternatives with noisy eviden... more Evidence integration is a normative algorithm for choosing between alternatives with noisy evidence. It has been successful in
accounting for vast amounts of behavioural and neural data. However, this mechanism has been challenged by non-integration
heuristics, and tracking decision boundaries has proven elusive. Here we first show that the decision boundary can be monitored
using a model-free behavioural method termed decision classification boundary, which extracts decision boundaries by
optimizing choice classification based on the accumulated evidence. Using this method, we provide direct support for evidence
integration over non-integration heuristics, show that the decision boundaries collapse across time and identify an integration
bias whereby incoming evidence is modulated based on its consistency with preceding information. This consistency bias,
which is a form of pre-decision confirmation bias, was supported in four cross-domain experiments, showing that choice accuracy
and decision confidence are modulated by stimulus consistency. Strikingly, despite its seeming sub-optimality, the consistency
bias fosters performance by enhancing robustness to integration noise.

The Cognition/Metacognition Trade-Off

by Marius usher and David Rosenbaum

PSYCHOLOGICAL SCIENCE, 2022

Integration to boundary is an optimal decision algorithm that accumulates evidence until the post... more Integration to boundary is an optimal decision algorithm that accumulates evidence until the posterior reaches a decision boundary, resulting in the fastest decisions for a target accuracy. Here, we demonstrated that this advantage incurs a cost in metacognitive accuracy (confidence), generating a cognition/metacognition trade-off. Using computational modeling, we found that integration to a fixed boundary results in less variability in evidence integration and thus reduces metacognitive accuracy, compared with a collapsing-boundary or a random-timer strategy. We examined how decision strategy affects metacognitive accuracy in three cross-domain experiments, in which 102 university students completed a free-response session (evidence terminated by the participant’s response) and an interrogation session (fixed number of evidence samples controlled by the experimenter). In both sessions, participants observed a sequence of evidence and reported their choice and confidence. As predicted, the interrogation protocol (preventing integration to boundary) enhanced metacognitive accuracy. We also found that in the free-response sessions, participants integrated evidence to a collapsing boundary—a strategy that achieves an efficient compromise between optimizing choice and metacognitive accuracy.

The efect of perceptual organization on numerical and preference‑based decisions shows inter‑subject correlation

by Marius usher and Moshe Glickman

Psychonomic Bulletin & Review, 2023

Individual differences in cognitive processing have been a subject of intensive research. One imp... more Individual differences in cognitive processing have been a subject of intensive research. One important type of such individual differences is the tendency for global versus local processing, which was shown to correlate with a wide range of processing differences in fields such as decision making, social judgments and creativity. Yet, whether these global/local processing tendencies are correlated within a subject across different domains is an open question. To address this question,
we develop and test a novel method to quantify global/local processing tendencies, in which we directly set in opposition the local/global information instead of instructing subjects to specifcally attend to one processing level. We apply our novel method to two different domains: (1) a numerical cognition task, and (2) a preference task. Using computational modeling, we account for classical effects in choice and numerical-cognition. Global/local tendencies in both tasks were quantified
using a salience parameter. Critically, the salience parameters extracted from the numerical cognition and preference tasks were highly correlated, providing support for robust perceptual organization tendencies within an individual.

When philosophical nuance matters: safeguarding consciousness research from restrictive assumptions

Frontiers in Psychology, Nov 26, 2023

In this paper, we revisit the debate surrounding the Unfolding Argument (UA) against causal struc... more In this paper, we revisit the debate surrounding the Unfolding Argument (UA) against causal structure theories of consciousness (as well as the hard-criteria research program it prescribes), using it as a platform for discussing theoretical and methodological issues in consciousness research. Causal structure theories assert that consciousness depends on a particular causal structure of the brain. Our claim is that some of the assumptions fueling the UA are not warranted, and therefore we should reject the methodology for consciousness science that the UA prescribes. First, we briefly survey the most popular philosophical positions in consciousness science, namely physicalism and functionalism. We discuss the relations between these positions and the behaviorist methodology that the UA assumptions express, despite the contrary claim of its proponents. Second, we argue that the same reasoning that the UA applies against causal structure theories can be applied to functionalist approaches, thus proving too much and deeming as unscientific a whole range of (non-causal structure) theories. Since this is overly restrictive and fits poorly with common practice in cognitive neuroscience, we suggest that the reasoning of the UA must be flawed. Third, we assess its philosophical assumptions, which express a restrictive methodology, and conclude that there are reasons to reject them. Finally, we propose a more inclusive methodology for consciousness science, that includes neural, behavioral, and phenomenological evidence (provided by the first-person perspective) without which consciousness science could not even start. Then, we extend this discussion to the scope of consciousness science, and conclude that theories of consciousness should be tested and evaluated on humans, and not on systems considerably different from us. Rather than restricting the methodology of consciousness science, we should, at this point, restrict the range of systems upon which it is supposed to be built.

Visual attention modulates the integration of goal-relevant evidence and not value

bioRxiv (Cold Spring Harbor Laboratory), Apr 14, 2020

When choosing between options, such as food items presented in plain view, people tend to choose ... more When choosing between options, such as food items presented in plain view, people tend to choose the option they spend longer looking at. The prevailing interpretation is that visual attention increases value. However, in previous studies, 'value' was coupled to a behavioural goal, since subjects had to choose the item they preferred. This makes it impossible to discern if visual attention has an effect on value, or, instead, if attention modulates the information most relevant for the goal of the decision-maker. Here we present the results of two independent studies-a perceptual and a value-based task-that allow us to decouple value from goalrelevant information using specific task-framing. Combining psychophysics with computational modelling, we show that, contrary to the current interpretation, attention does not boost value, but instead it modulates goal-relevant information. This work provides a novel and more general mechanism by which attention interacts with choice.

An appeal against the item's death sentence: Accounting for diagnostic data patterns with an item-based model of visual search

Behavioral and Brain Sciences, 2017

We show that our item-based model, competitive guided search, accounts for the empirical patterns... more We show that our item-based model, competitive guided search, accounts for the empirical patterns that Hulleman & Olivers (H&O) invoke against item-based models, and we highlight recently reported diagnostic data that challenge their approach. We advise against “forsaking the item” unless and until a full fixation-based model is shown to be superior to extant item-based models.

The averaging of numerosities: A psychometric investigation of the mental line

Attention, Perception, & Psychophysics, 2020

Humans and animals are capable of estimating and discriminating nonsymbolic numerosities via ment... more Humans and animals are capable of estimating and discriminating nonsymbolic numerosities via mental representation of magnitudes-the approximate number system (ANS). There are two models of the ANS system, which are similar in their prediction in numerosity discrimination tasks. The log-Gaussian model, which assumes numerosities are represented on a compressed logarithmic scale, and the scalar variability model, which assumes numerosities are represented on a linear scale. In the first experiment of this paper, we contrasted these models using averaging of numerosities. We examined whether participants generate a compressed mean (i.e., geometric mean) or a linear mean when averaging two numerosities. Our results demonstrated that half of the participants are linear and half are compressed; however, in general, the compression is milder than a logarithmic compression. In Experiments 2 and 3, we examined averaging of numerosities in sequences larger than two. We found that averaging precision increases with sequence length. These results are in line with previous findings, suggesting a mechanism in which the estimate is generated by population averaging of the responses each stimulus generates on the numerosity representation.

Choices Change the Temporal Weighting of Decision Evidence

ABSTRACTDecisions do not occur in isolation, but are embedded in sequences of other decisions, of... more ABSTRACTDecisions do not occur in isolation, but are embedded in sequences of other decisions, often pertaining to the same source of evidence. Here, we characterized the impact of intermittent choices on the accumulation of a protracted stream of decision-relevant evidence towards a final decision. Human participants performed two versions, based on perceptual or numerical evidence, of a decision task that required two successive judgments at different times during the evidence stream: an intermittent response consisting of a binary choice, and a continuous estimation at the end of the evidence stream. In a control condition, subjects executed a choice-independent motor response instead of binary choice as the intermittent response. In both, perceptual and numerical tasks, the intermittent choice reduced the sensitivity of subsequent evidence, and flipped the relative temporal weighting of early and late evidence in the final estimation judgment. The individual extent of the choice...

Age-Related Deficits in Memory Encoding and Retrieval in Word List Free Recall

Brain Sciences, 2018

Although ageing is known to affect memory, the precise nature of its effect on retrieval and enco... more Although ageing is known to affect memory, the precise nature of its effect on retrieval and encoding processes is not well understood. Here, we examine the effect of ageing on the free recall of word lists, in which the semantic structure of word sequences was manipulated from unrelated words to pairs of associated words with various separations (between pair members) within the sequence. We find that ageing is associated with reduced total recall, especially for sequences with associated words. Furthermore, we find that the degree of semantic clustering (controlled for chance clustering) shows an age effect and that it interacts with the distance between the words within a pair. The results are consistent with the view that age effects in memory are mediated both by retrieval and by encoding processes associated with frontal control and working memory.

Violations of choice transitivity depend on “within-attribute” vs. “within-alternative” processes

Research Square (Research Square), Jun 5, 2023

Choice transitivity (CT) is a central axiom of rationality. While violating CT is rare, there hav... more Choice transitivity (CT) is a central axiom of rationality. While violating CT is rare, there have been reports of such violations (Tversky, 1969; Tsetsos et al., 2016; but see Regenwetter, 2011). If humans indeed violate CT, an important challenge is understanding the conditions that promote intransitive choices and the mechanisms that support it. Here, we report the presence of CT violations (CTV) using a strict data analysis method (Regenwetter, 2011) and an experimental design where each choice is presented on a single visual display, avoiding averaging artifacts (Davis-Stober et al., 2016). In three experiments (one of which is a preregistered replication), we provide evidence for CTV in human (student) participants. In addition, we find a dependence of the CTV-rate on the mode of information processing. A higher CTV-rate occurs when the choice stimuli are presented grouped by attributes compared to when the same stimuli are grouped by alternatives.

Ensemble perception: Extracting the average of perceptual versus numerical stimuli

Attention, perception & psychophysics, Jan 3, 2021

Recent research has established that humans can extract the average perceptual feature over brief... more Recent research has established that humans can extract the average perceptual feature over briefly presented arrays of visual elements or the average of a rapid temporal sequence of numbers. Here we compared the extraction of the average over briefly presented arrays, for a perceptual feature (orientations) and for numerical values (1–9 digits), using an identical experimental design for the two tasks. We hypothesized that the averaging of numbers, more than of orientations, would be constrained by capacity limitations. Arrays of Gabor elements or digits were simultaneously presented for 300 ms and observers were required to estimate the average on a continuous response scale. In each trial the elements were sampled from normal distributions (of various means) and we varied the set size (4–12). We found that while for orientation the averaging precision remained constant with set size, for numbers it decreased with set size. Using computational modeling we also extracted capacity parameters (the number of elements that are pooled in the average extraction). Despite marked heterogeneity between observers, the capacity for orientations (around eight items) was much larger than for numbers (around four items). The orientation task also had a larger fraction of participants relying on distributed attention to all elements. Our study thus supports the idea that numbers more than perceptual features are subject to capacity or attentional limitations when observers need to evaluate the average over an ensemble of stimuli.

Visual attention modulates the integration of goal-relevant evidence and not value

eLife, Nov 17, 2020

When choosing between options, such as food items presented in plain view, people tend to choose ... more When choosing between options, such as food items presented in plain view, people tend to choose the option they spend longer looking at. The prevailing interpretation is that visual attention increases value. However, in previous studies, 'value' was coupled to a behavioural goal, since subjects had to choose the item they preferred. This makes it impossible to discern if visual attention has an effect on value, or, instead, if attention modulates the information most relevant for the goal of the decision-maker. Here, we present the results of two independent studies-a perceptual and a value-based task-that allow us to decouple value from goal-relevant information using specific task-framing. Combining psychophysics with computational modelling, we show that, contrary to the current interpretation, attention does not boost value, but instead it modulates goal-relevant information. This work provides a novel and more general mechanism by which attention interacts with choice.

Preference for a Compromise Increases as Choice Alternatives Become More Extreme

PsycEXTRA Dataset, 2004

Ensemble perception: extracting the average of perceptual vs numerical stimuli

Recent research has established that humans can extract an average perceptual feature over briefl... more Recent research has established that humans can extract an average perceptual feature over briefly presented arrays of visual elements or the average of a rapid temporal sequence of numbers. Here we compared the extraction of the average over briefly presented arrays, for a perceptual feature (orientations) and for numerical values (1-9 digits), using an identical experimental design for the two tasks. We hypothesized that the averaging of numbers, more than of orientations, would be constrained by capacity limitations. Arrays of Gabor elements or digits were simultaneously presented for 300 ms and observers were required to estimate the average on a continuous response scale.

The averaging of numerosities: A psychometric investigation of the mental line

Attention, perception & psychophysics, Oct 19, 2020

Humans and animals are capable of estimating and discriminating nonsymbolic numerosities via ment... more Humans and animals are capable of estimating and discriminating nonsymbolic numerosities via mental representation of magnitudes-the approximate number system (ANS). There are two models of the ANS system, which are similar in their prediction in numerosity discrimination tasks. The log-Gaussian model, which assumes numerosities are represented on a compressed logarithmic scale, and the scalar variability model, which assumes numerosities are represented on a linear scale. In the first experiment of this paper, we contrasted these models using averaging of numerosities. We examined whether participants generate a compressed mean (i.e., geometric mean) or a linear mean when averaging two numerosities. Our results demonstrated that half of the participants are linear and half are compressed; however, in general, the compression is milder than a logarithmic compression. In Experiments 2 and 3, we examined averaging of numerosities in sequences larger than two. We found that averaging precision increases with sequence length. These results are in line with previous findings, suggesting a mechanism in which the estimate is generated by population averaging of the responses each stimulus generates on the numerosity representation.

Reports of the Demise of Short-Term Memory Are Much Exaggerated

PsycEXTRA Dataset, 2000

A Network for Semantic and Episodic Associations Showing Disturbances Due to Neural Loss

Springer eBooks, 1993

We study an Attractor Neural Network that stores natural concepts, organized in semantic classes.... more We study an Attractor Neural Network that stores natural concepts, organized in semantic classes. The concepts are related by both semantic and episodic associations. When neurons characterized by large synaptic connectivity are deleted, semantic transitions among concepts decay before the episodic ones, in accordance with the findings in patients with Alzheimer’s disease.

Attentional Selection Mediates Framing and Risk-Bias Effects

Psychological Science, Nov 7, 2018

, 1947), humans should have stable preferences that do not vary with context (i.e., the relative ... more , 1947), humans should have stable preferences that do not vary with context (i.e., the relative preference between A and B should not change when a new option C is made available) or with task framing (the preference between A and B should not depend on whether the decision maker is asked to select or reject one of them). Nevertheless, a variety of such choice-bias effects was reported in decision-making studies that used multiattribute alternatives (Berkowitsch, Scheibehenne, & Rieskamp, 2014; Simonson, 1989; Tversky, 1972) or choices between sequences of differently framed or temporally correlated payoffs (Pachur & Scheibehenne, 2012; Shafir, 1993; Tsetsos, Chater, & Usher, 2012). Choices between sequences of payoffs or evidence samples are encountered in many real-life situations, such as selecting a stock on the basis of fluctuating returns or deciding on the culpability of a defendant in a legal case on the basis of sequential pieces of evidence. Moreover, a number of prominent decision theories have suggested that even for decisions between static alternatives (in the domain of risk or multiattribute decisions), the decision mechanism operates by dynamically integrating sequences of internally generated samples (decision field theory: Busemeyer & Townsend, 1993; Roe, Busemeyer, & Townsend, 2001; associativeaccumulation model: Bhatia, 2013; leaky competing accumulators: Usher & McClelland, 2004). Here, we focus on choices between externally controlled potential payoff sequences, which allow us to control the objective properties of the alternatives and measure their impact on risk preferences (Tsetsos et al., 2012; Zeigenfuse, Pleskac, & Liu, 2014). Do people prefer an alternative that is characterized by a broader (riskier) distribution of payoffs over a narrower (safer) one, or the other way 803643P SSXXX10.

Choices Change the Temporal Weighting of Decision Evidence

bioRxiv (Cold Spring Harbor Laboratory), Mar 6, 2020

Decisions do not occur in isolation, but are embedded in sequences of other decisions, often pert... more Decisions do not occur in isolation, but are embedded in sequences of other decisions, often pertaining to the same source of evidence. Here, we characterized the impact of intermittent choices on the accumulation of a protracted stream of decision-relevant evidence towards a final decision. Human participants performed two versions, based on perceptual or numerical evidence, of a decision task that required two successive judgments at different times during the evidence stream: an intermittent response consisting of a binary choice, and a continuous estimation at the end of the evidence stream. In a control condition, subjects executed a choice-independent motor response instead of binary choice as the intermittent response. In both, perceptual and numerical tasks, the intermittent choice reduced the sensitivity of subsequent evidence, and flipped the relative temporal weighting of early and late evidence in the final estimation judgment. The individual extent of the choice-induced overall (nonselective) sensitivity reduction predicted the extent of the selective down-weighting of subsequent evidence inconsistent with the initial choice, a form of confirmation bias. In sum, active decisions about a protracted evidence stream profoundly alter the dynamics of evidence accumulation, consistent with an active, modulatory mechanism triggered by the choice.

S2.0 S1053810024001508 main

Consciousness and Coggnition, 2024

A fundamental question in the domain of affect and conscious perception is whether the former can... more A fundamental question in the domain of affect and conscious perception is whether the former can impact the latter. Traditionally, perception and affect were conceived as largely independent. Against this backdrop, it was recently argued that the affective valence of a stimulus can modulate the perceptual experience of its sensory features. An alternative hypothesis is that perceptual experiences have a valenced aspect over and above their sensory aspects, with these two aspects interacting and comprising integral perceptual dimensions. To test this, we carried out two experiments deploying Wendell Garner’s speeded classification paradigm to decide whether visual brightness and affective valence are separable or integral dimensions. We found Garner interference, documenting that brightness and valence are integral dimensions. We did not observe effects of congruity – responses to bright positive stimuli were not faster than to bright negative stimuli — providing no support for affect induced changes in the perception of brightness.

Evidence integration and decision confidence are modulated by stimulus consistency

Nature Human Behaviour, 2022

Evidence integration is a normative algorithm for choosing between alternatives with noisy eviden... more Evidence integration is a normative algorithm for choosing between alternatives with noisy evidence. It has been successful in
accounting for vast amounts of behavioural and neural data. However, this mechanism has been challenged by non-integration
heuristics, and tracking decision boundaries has proven elusive. Here we first show that the decision boundary can be monitored
using a model-free behavioural method termed decision classification boundary, which extracts decision boundaries by
optimizing choice classification based on the accumulated evidence. Using this method, we provide direct support for evidence
integration over non-integration heuristics, show that the decision boundaries collapse across time and identify an integration
bias whereby incoming evidence is modulated based on its consistency with preceding information. This consistency bias,
which is a form of pre-decision confirmation bias, was supported in four cross-domain experiments, showing that choice accuracy
and decision confidence are modulated by stimulus consistency. Strikingly, despite its seeming sub-optimality, the consistency
bias fosters performance by enhancing robustness to integration noise.

The Cognition/Metacognition Trade-Off

by Marius usher and David Rosenbaum

PSYCHOLOGICAL SCIENCE, 2022

Integration to boundary is an optimal decision algorithm that accumulates evidence until the post... more Integration to boundary is an optimal decision algorithm that accumulates evidence until the posterior reaches a decision boundary, resulting in the fastest decisions for a target accuracy. Here, we demonstrated that this advantage incurs a cost in metacognitive accuracy (confidence), generating a cognition/metacognition trade-off. Using computational modeling, we found that integration to a fixed boundary results in less variability in evidence integration and thus reduces metacognitive accuracy, compared with a collapsing-boundary or a random-timer strategy. We examined how decision strategy affects metacognitive accuracy in three cross-domain experiments, in which 102 university students completed a free-response session (evidence terminated by the participant’s response) and an interrogation session (fixed number of evidence samples controlled by the experimenter). In both sessions, participants observed a sequence of evidence and reported their choice and confidence. As predicted, the interrogation protocol (preventing integration to boundary) enhanced metacognitive accuracy. We also found that in the free-response sessions, participants integrated evidence to a collapsing boundary—a strategy that achieves an efficient compromise between optimizing choice and metacognitive accuracy.

The efect of perceptual organization on numerical and preference‑based decisions shows inter‑subject correlation

by Marius usher and Moshe Glickman

Psychonomic Bulletin & Review, 2023

Individual differences in cognitive processing have been a subject of intensive research. One imp... more Individual differences in cognitive processing have been a subject of intensive research. One important type of such individual differences is the tendency for global versus local processing, which was shown to correlate with a wide range of processing differences in fields such as decision making, social judgments and creativity. Yet, whether these global/local processing tendencies are correlated within a subject across different domains is an open question. To address this question,
we develop and test a novel method to quantify global/local processing tendencies, in which we directly set in opposition the local/global information instead of instructing subjects to specifcally attend to one processing level. We apply our novel method to two different domains: (1) a numerical cognition task, and (2) a preference task. Using computational modeling, we account for classical effects in choice and numerical-cognition. Global/local tendencies in both tasks were quantified
using a salience parameter. Critically, the salience parameters extracted from the numerical cognition and preference tasks were highly correlated, providing support for robust perceptual organization tendencies within an individual.

When philosophical nuance matters: safeguarding consciousness research from restrictive assumptions

Frontiers in Psychology, Nov 26, 2023

In this paper, we revisit the debate surrounding the Unfolding Argument (UA) against causal struc... more In this paper, we revisit the debate surrounding the Unfolding Argument (UA) against causal structure theories of consciousness (as well as the hard-criteria research program it prescribes), using it as a platform for discussing theoretical and methodological issues in consciousness research. Causal structure theories assert that consciousness depends on a particular causal structure of the brain. Our claim is that some of the assumptions fueling the UA are not warranted, and therefore we should reject the methodology for consciousness science that the UA prescribes. First, we briefly survey the most popular philosophical positions in consciousness science, namely physicalism and functionalism. We discuss the relations between these positions and the behaviorist methodology that the UA assumptions express, despite the contrary claim of its proponents. Second, we argue that the same reasoning that the UA applies against causal structure theories can be applied to functionalist approaches, thus proving too much and deeming as unscientific a whole range of (non-causal structure) theories. Since this is overly restrictive and fits poorly with common practice in cognitive neuroscience, we suggest that the reasoning of the UA must be flawed. Third, we assess its philosophical assumptions, which express a restrictive methodology, and conclude that there are reasons to reject them. Finally, we propose a more inclusive methodology for consciousness science, that includes neural, behavioral, and phenomenological evidence (provided by the first-person perspective) without which consciousness science could not even start. Then, we extend this discussion to the scope of consciousness science, and conclude that theories of consciousness should be tested and evaluated on humans, and not on systems considerably different from us. Rather than restricting the methodology of consciousness science, we should, at this point, restrict the range of systems upon which it is supposed to be built.

Visual attention modulates the integration of goal-relevant evidence and not value

bioRxiv (Cold Spring Harbor Laboratory), Apr 14, 2020

When choosing between options, such as food items presented in plain view, people tend to choose ... more When choosing between options, such as food items presented in plain view, people tend to choose the option they spend longer looking at. The prevailing interpretation is that visual attention increases value. However, in previous studies, 'value' was coupled to a behavioural goal, since subjects had to choose the item they preferred. This makes it impossible to discern if visual attention has an effect on value, or, instead, if attention modulates the information most relevant for the goal of the decision-maker. Here we present the results of two independent studies-a perceptual and a value-based task-that allow us to decouple value from goalrelevant information using specific task-framing. Combining psychophysics with computational modelling, we show that, contrary to the current interpretation, attention does not boost value, but instead it modulates goal-relevant information. This work provides a novel and more general mechanism by which attention interacts with choice.

An appeal against the item's death sentence: Accounting for diagnostic data patterns with an item-based model of visual search

Behavioral and Brain Sciences, 2017

We show that our item-based model, competitive guided search, accounts for the empirical patterns... more We show that our item-based model, competitive guided search, accounts for the empirical patterns that Hulleman & Olivers (H&O) invoke against item-based models, and we highlight recently reported diagnostic data that challenge their approach. We advise against “forsaking the item” unless and until a full fixation-based model is shown to be superior to extant item-based models.

The averaging of numerosities: A psychometric investigation of the mental line

Attention, Perception, & Psychophysics, 2020

Humans and animals are capable of estimating and discriminating nonsymbolic numerosities via ment... more Humans and animals are capable of estimating and discriminating nonsymbolic numerosities via mental representation of magnitudes-the approximate number system (ANS). There are two models of the ANS system, which are similar in their prediction in numerosity discrimination tasks. The log-Gaussian model, which assumes numerosities are represented on a compressed logarithmic scale, and the scalar variability model, which assumes numerosities are represented on a linear scale. In the first experiment of this paper, we contrasted these models using averaging of numerosities. We examined whether participants generate a compressed mean (i.e., geometric mean) or a linear mean when averaging two numerosities. Our results demonstrated that half of the participants are linear and half are compressed; however, in general, the compression is milder than a logarithmic compression. In Experiments 2 and 3, we examined averaging of numerosities in sequences larger than two. We found that averaging precision increases with sequence length. These results are in line with previous findings, suggesting a mechanism in which the estimate is generated by population averaging of the responses each stimulus generates on the numerosity representation.

Choices Change the Temporal Weighting of Decision Evidence

ABSTRACTDecisions do not occur in isolation, but are embedded in sequences of other decisions, of... more ABSTRACTDecisions do not occur in isolation, but are embedded in sequences of other decisions, often pertaining to the same source of evidence. Here, we characterized the impact of intermittent choices on the accumulation of a protracted stream of decision-relevant evidence towards a final decision. Human participants performed two versions, based on perceptual or numerical evidence, of a decision task that required two successive judgments at different times during the evidence stream: an intermittent response consisting of a binary choice, and a continuous estimation at the end of the evidence stream. In a control condition, subjects executed a choice-independent motor response instead of binary choice as the intermittent response. In both, perceptual and numerical tasks, the intermittent choice reduced the sensitivity of subsequent evidence, and flipped the relative temporal weighting of early and late evidence in the final estimation judgment. The individual extent of the choice...

Age-Related Deficits in Memory Encoding and Retrieval in Word List Free Recall

Brain Sciences, 2018

Although ageing is known to affect memory, the precise nature of its effect on retrieval and enco... more Although ageing is known to affect memory, the precise nature of its effect on retrieval and encoding processes is not well understood. Here, we examine the effect of ageing on the free recall of word lists, in which the semantic structure of word sequences was manipulated from unrelated words to pairs of associated words with various separations (between pair members) within the sequence. We find that ageing is associated with reduced total recall, especially for sequences with associated words. Furthermore, we find that the degree of semantic clustering (controlled for chance clustering) shows an age effect and that it interacts with the distance between the words within a pair. The results are consistent with the view that age effects in memory are mediated both by retrieval and by encoding processes associated with frontal control and working memory.

Violations of choice transitivity depend on “within-attribute” vs. “within-alternative” processes

Research Square (Research Square), Jun 5, 2023

Choice transitivity (CT) is a central axiom of rationality. While violating CT is rare, there hav... more Choice transitivity (CT) is a central axiom of rationality. While violating CT is rare, there have been reports of such violations (Tversky, 1969; Tsetsos et al., 2016; but see Regenwetter, 2011). If humans indeed violate CT, an important challenge is understanding the conditions that promote intransitive choices and the mechanisms that support it. Here, we report the presence of CT violations (CTV) using a strict data analysis method (Regenwetter, 2011) and an experimental design where each choice is presented on a single visual display, avoiding averaging artifacts (Davis-Stober et al., 2016). In three experiments (one of which is a preregistered replication), we provide evidence for CTV in human (student) participants. In addition, we find a dependence of the CTV-rate on the mode of information processing. A higher CTV-rate occurs when the choice stimuli are presented grouped by attributes compared to when the same stimuli are grouped by alternatives.

Ensemble perception: Extracting the average of perceptual versus numerical stimuli

Attention, perception & psychophysics, Jan 3, 2021

Recent research has established that humans can extract the average perceptual feature over brief... more Recent research has established that humans can extract the average perceptual feature over briefly presented arrays of visual elements or the average of a rapid temporal sequence of numbers. Here we compared the extraction of the average over briefly presented arrays, for a perceptual feature (orientations) and for numerical values (1–9 digits), using an identical experimental design for the two tasks. We hypothesized that the averaging of numbers, more than of orientations, would be constrained by capacity limitations. Arrays of Gabor elements or digits were simultaneously presented for 300 ms and observers were required to estimate the average on a continuous response scale. In each trial the elements were sampled from normal distributions (of various means) and we varied the set size (4–12). We found that while for orientation the averaging precision remained constant with set size, for numbers it decreased with set size. Using computational modeling we also extracted capacity parameters (the number of elements that are pooled in the average extraction). Despite marked heterogeneity between observers, the capacity for orientations (around eight items) was much larger than for numbers (around four items). The orientation task also had a larger fraction of participants relying on distributed attention to all elements. Our study thus supports the idea that numbers more than perceptual features are subject to capacity or attentional limitations when observers need to evaluate the average over an ensemble of stimuli.

Visual attention modulates the integration of goal-relevant evidence and not value

eLife, Nov 17, 2020

When choosing between options, such as food items presented in plain view, people tend to choose ... more When choosing between options, such as food items presented in plain view, people tend to choose the option they spend longer looking at. The prevailing interpretation is that visual attention increases value. However, in previous studies, 'value' was coupled to a behavioural goal, since subjects had to choose the item they preferred. This makes it impossible to discern if visual attention has an effect on value, or, instead, if attention modulates the information most relevant for the goal of the decision-maker. Here, we present the results of two independent studies-a perceptual and a value-based task-that allow us to decouple value from goal-relevant information using specific task-framing. Combining psychophysics with computational modelling, we show that, contrary to the current interpretation, attention does not boost value, but instead it modulates goal-relevant information. This work provides a novel and more general mechanism by which attention interacts with choice.

Preference for a Compromise Increases as Choice Alternatives Become More Extreme

PsycEXTRA Dataset, 2004

Ensemble perception: extracting the average of perceptual vs numerical stimuli

Recent research has established that humans can extract an average perceptual feature over briefl... more Recent research has established that humans can extract an average perceptual feature over briefly presented arrays of visual elements or the average of a rapid temporal sequence of numbers. Here we compared the extraction of the average over briefly presented arrays, for a perceptual feature (orientations) and for numerical values (1-9 digits), using an identical experimental design for the two tasks. We hypothesized that the averaging of numbers, more than of orientations, would be constrained by capacity limitations. Arrays of Gabor elements or digits were simultaneously presented for 300 ms and observers were required to estimate the average on a continuous response scale.

The averaging of numerosities: A psychometric investigation of the mental line

Attention, perception & psychophysics, Oct 19, 2020

Humans and animals are capable of estimating and discriminating nonsymbolic numerosities via ment... more Humans and animals are capable of estimating and discriminating nonsymbolic numerosities via mental representation of magnitudes-the approximate number system (ANS). There are two models of the ANS system, which are similar in their prediction in numerosity discrimination tasks. The log-Gaussian model, which assumes numerosities are represented on a compressed logarithmic scale, and the scalar variability model, which assumes numerosities are represented on a linear scale. In the first experiment of this paper, we contrasted these models using averaging of numerosities. We examined whether participants generate a compressed mean (i.e., geometric mean) or a linear mean when averaging two numerosities. Our results demonstrated that half of the participants are linear and half are compressed; however, in general, the compression is milder than a logarithmic compression. In Experiments 2 and 3, we examined averaging of numerosities in sequences larger than two. We found that averaging precision increases with sequence length. These results are in line with previous findings, suggesting a mechanism in which the estimate is generated by population averaging of the responses each stimulus generates on the numerosity representation.

Reports of the Demise of Short-Term Memory Are Much Exaggerated

PsycEXTRA Dataset, 2000

A Network for Semantic and Episodic Associations Showing Disturbances Due to Neural Loss

Springer eBooks, 1993

We study an Attractor Neural Network that stores natural concepts, organized in semantic classes.... more We study an Attractor Neural Network that stores natural concepts, organized in semantic classes. The concepts are related by both semantic and episodic associations. When neurons characterized by large synaptic connectivity are deleted, semantic transitions among concepts decay before the episodic ones, in accordance with the findings in patients with Alzheimer’s disease.

Attentional Selection Mediates Framing and Risk-Bias Effects

Psychological Science, Nov 7, 2018

, 1947), humans should have stable preferences that do not vary with context (i.e., the relative ... more , 1947), humans should have stable preferences that do not vary with context (i.e., the relative preference between A and B should not change when a new option C is made available) or with task framing (the preference between A and B should not depend on whether the decision maker is asked to select or reject one of them). Nevertheless, a variety of such choice-bias effects was reported in decision-making studies that used multiattribute alternatives (Berkowitsch, Scheibehenne, & Rieskamp, 2014; Simonson, 1989; Tversky, 1972) or choices between sequences of differently framed or temporally correlated payoffs (Pachur & Scheibehenne, 2012; Shafir, 1993; Tsetsos, Chater, & Usher, 2012). Choices between sequences of payoffs or evidence samples are encountered in many real-life situations, such as selecting a stock on the basis of fluctuating returns or deciding on the culpability of a defendant in a legal case on the basis of sequential pieces of evidence. Moreover, a number of prominent decision theories have suggested that even for decisions between static alternatives (in the domain of risk or multiattribute decisions), the decision mechanism operates by dynamically integrating sequences of internally generated samples (decision field theory: Busemeyer & Townsend, 1993; Roe, Busemeyer, & Townsend, 2001; associativeaccumulation model: Bhatia, 2013; leaky competing accumulators: Usher & McClelland, 2004). Here, we focus on choices between externally controlled potential payoff sequences, which allow us to control the objective properties of the alternatives and measure their impact on risk preferences (Tsetsos et al., 2012; Zeigenfuse, Pleskac, & Liu, 2014). Do people prefer an alternative that is characterized by a broader (riskier) distribution of payoffs over a narrower (safer) one, or the other way 803643P SSXXX10.

Choices Change the Temporal Weighting of Decision Evidence

bioRxiv (Cold Spring Harbor Laboratory), Mar 6, 2020

Decisions do not occur in isolation, but are embedded in sequences of other decisions, often pert... more Decisions do not occur in isolation, but are embedded in sequences of other decisions, often pertaining to the same source of evidence. Here, we characterized the impact of intermittent choices on the accumulation of a protracted stream of decision-relevant evidence towards a final decision. Human participants performed two versions, based on perceptual or numerical evidence, of a decision task that required two successive judgments at different times during the evidence stream: an intermittent response consisting of a binary choice, and a continuous estimation at the end of the evidence stream. In a control condition, subjects executed a choice-independent motor response instead of binary choice as the intermittent response. In both, perceptual and numerical tasks, the intermittent choice reduced the sensitivity of subsequent evidence, and flipped the relative temporal weighting of early and late evidence in the final estimation judgment. The individual extent of the choice-induced overall (nonselective) sensitivity reduction predicted the extent of the selective down-weighting of subsequent evidence inconsistent with the initial choice, a form of confirmation bias. In sum, active decisions about a protracted evidence stream profoundly alter the dynamics of evidence accumulation, consistent with an active, modulatory mechanism triggered by the choice.

The neurodynamics of choice value based

The Probabilistic Mind: Prospects for Bayesian cognitive science, Eds. Chater N & Oaksford M. , 2008

We contrast computational models for contextual preference reversal, in particular in accounting ... more We contrast computational models for contextual preference reversal, in particular in accounting for the comprise effect. We focus in particular on the LCA and DFT models. These models share many processing assumptions but vary on a number of important but secondary mechanisms. We highlight their common approach by contrast with heuristic approaches and we briefly address some implications to the debate on rationality in human choice.