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Van den Berg, Ronald
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Publications (10 of 19) Show all publications
Poom, L., Lindskog, M., Winman, A. & Van den Berg, R. (2019). Grouping effects in numerosity perception under prolonged viewing conditions. PLoS ONE, 14(2), Article ID e0207502.
Open this publication in new window or tab >>Grouping effects in numerosity perception under prolonged viewing conditions
2019 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 14, no 2, article id e0207502Article in journal (Refereed) Published
Abstract [en]

Humans can estimate numerosities–such as the number sheep in a flock–without deliberate counting. A number of biases have been identified in these estimates, which seem primarily rooted in the spatial organization of objects (grouping, symmetry, etc). Most previous studies on the number sense used static stimuli with extremely brief exposure times. However, outside the laboratory, visual scenes are often dynamic and freely viewed for prolonged durations (e.g., a flock of moving sheep). The purpose of the present study is to examine grouping-induced numerosity biases in stimuli that more closely mimic these conditions. To this end, we designed two experiments with limited-dot-lifetime displays (LDDs), in which each dot is visible for a brief period of time and replaced by a new dot elsewhere after its disappearance. The dynamic nature of LDDs prevents subjects from counting even when they are free-viewing a stimulus under prolonged presentation. Subjects estimated the number of dots in arrays that were presented either as a single group or were segregated into two groups by spatial clustering, dot size, dot color, or dot motion. Grouping by color and motion reduced perceived numerosity compared to viewing them as a single group. Moreover, the grouping effect sizes between these two features were correlated, which suggests that the effects may share a common, feature-invariant mechanism. Finally, we find that dot size and total stimulus area directly affect perceived numerosity, which makes it difficult to draw reliable conclusions about grouping effects induced by spatial clustering and dot size. Our results provide new insights into biases in numerosity estimation and they demonstrate that the use of LDDs is an effective method to study the human number sense under prolonged viewing.

Place, publisher, year, edition, pages
Public Library of Science, 2019
National Category
Psychology
Identifiers
urn:nbn:se:uu:diva-377185 (URN)10.1371/journal.pone.0207502 (DOI)000458761300006 ()
Funder
Swedish Research Council, 2015-00371Swedish Research Council, 2013-01005
Note

Leo Poom and Ronald van der Berg contributed equally to this work.

Available from: 2019-02-15 Created: 2019-02-15 Last updated: 2019-08-01Bibliographically approved
Stengård, E. & Van den Berg, R. (2019). Imperfect Bayesian inference in visual perception. PloS Computational Biology, 15(4), Article ID e1006465.
Open this publication in new window or tab >>Imperfect Bayesian inference in visual perception
2019 (English)In: PloS Computational Biology, ISSN 1553-734X, E-ISSN 1553-7358, Vol. 15, no 4, article id e1006465Article in journal (Refereed) Published
Abstract [en]

The main task of perceptual systems is to make truthful inferences about the environment. The sensory input to these systems is often astonishingly imprecise, which makes human perception prone to error. Nevertheless, numerous studies have reported that humans often perform as accurately as is possible given these sensory imprecisions. This suggests that the brain makes optimal use of the sensory input and computes without error. The validity of this claim has recently been questioned for two reasons. First, it has been argued that a lot of the evidence for optimality comes from studies that used overly flexible models. Second, optimality in human perception is implausible due to limitations inherent to neural systems. In this study, we reconsider optimality in a standard visual perception task by devising a research method that addresses both concerns. In contrast to previous studies, we find clear indications of suboptimalities. Our data are best explained by a model that is based on the optimal decision strategy, but with imperfections in its execution.

National Category
Psychology
Identifiers
urn:nbn:se:uu:diva-382226 (URN)10.1371/journal.pcbi.1006465 (DOI)000467530600005 ()30998675 (PubMedID)
Funder
Swedish Research Council, 2015-00371
Available from: 2019-04-23 Created: 2019-04-23 Last updated: 2019-06-05Bibliographically approved
Van den Berg, R. & Ma, W. J. (2018). A resource-rational theory of set size effects in human visual working memory. eLIFE, 7, Article ID e34963.
Open this publication in new window or tab >>A resource-rational theory of set size effects in human visual working memory
2018 (English)In: eLIFE, E-ISSN 2050-084X, Vol. 7, article id e34963Article in journal (Refereed) Published
Abstract [en]

Encoding precision in visual working memory decreases with the number of encoded items. Here, we propose a normative theory for such set size effects: the brain minimizes a weighted sum of an error-based behavioral cost and a neural encoding cost. We construct a model from this theory and find that it predicts set size effects. Notably, these effects are mediated by probing probability, which aligns with previous empirical findings. The model accounts well for effects of both set size and probing probability on encoding precision in nine delayed-estimation experiments. Moreover, we find support for the prediction that the total amount of invested resource can vary non-monotonically with set size. Finally, we show that it is sometimes optimal to encode only a subset or even none of the relevant items in a task. Our findings raise the possibility that cognitive 'limitations' arise from rational cost minimization rather than from constraints.

Place, publisher, year, edition, pages
eLife Sciences Publications, Ltd, 2018
National Category
Psychology
Identifiers
urn:nbn:se:uu:diva-357477 (URN)10.7554/eLife.34963 (DOI)000442725600001 ()30084356 (PubMedID)
Funder
Swedish Research Council, 2015-00371
Available from: 2018-08-16 Created: 2018-08-16 Last updated: 2018-10-22Bibliographically approved
Van den Berg, R., Yoo, A. H. & Ma, W. J. (2017). Fechner’s law in metacognition: A quantitative model of visual working memory confidence.. Psychological Review, 124(2), 197-214
Open this publication in new window or tab >>Fechner’s law in metacognition: A quantitative model of visual working memory confidence.
2017 (English)In: Psychological Review, ISSN 0033-295XPrint, Vol. 124, no 2, p. 197-214Article in journal (Refereed) Published
Abstract [en]

Although visual working memory (VWM) has been studied extensively, it is unknown how people form confidence judgments about their memories. Peirce (1878) speculated that Fechner’s law—which states that sensation is proportional to the logarithm of stimulus intensity—might apply to confidence reports. Based on this idea, we hypothesize that humans map the precision of their VWM contents to a confidence rating through Fechner’s law. We incorporate this hypothesis into the best available model of VWM encoding and fit it to data from a delayed-estimation experiment. The model provides an excellent account of human confidence rating distributions as well as the relation between performance and confidence. Moreover, the best-fitting mapping in a model with a highly flexible mapping closely resembles the logarithmic mapping, suggesting that no alternative mapping exists that accounts better for the data than Fechner’s law. We propose a neural implementation of the model and find that this model also fits the behavioral data well. Furthermore, we find that jointly fitting memory errors and confidence ratings boosts the power to distinguish previously proposed VWM encoding models by a factor of 5.99 compared to fitting only memory errors. Finally, we show that Fechner’s law also accounts for metacognitive judgments in a word recognition memory task, which is a first indication that it may be a general law in metacognition. Our work presents the first model to jointly account for errors and confidence ratings in VWM and could lay the groundwork for understanding the computational mechanisms of metacognition.

Keywords
*Metacognition, *Recognition (Learning), *Self-Confidence, *Short Term Memory, *Visual Memory, Human Information Storage, Models
National Category
Psychology
Identifiers
urn:nbn:se:uu:diva-317419 (URN)10.1037/rev0000060 (DOI)000395865300006 ()28221087 (PubMedID)
Available from: 2017-03-14 Created: 2017-03-14 Last updated: 2018-09-26Bibliographically approved
Van den Berg, R., Lindskog, M., Poom, L. & Winman, A. (2017). Recent Is More: A Negative Time-Order Effect in Nonsymbolic Numerical Judgment.. Journal of Experimental Psychology: Human Perception and Performance, 43(6), 1084-1097
Open this publication in new window or tab >>Recent Is More: A Negative Time-Order Effect in Nonsymbolic Numerical Judgment.
2017 (English)In: Journal of Experimental Psychology: Human Perception and Performance, ISSN 0096-1523Print, Vol. 43, no 6, p. 1084-1097Article in journal (Refereed) Published
Abstract [en]

Humans as well as some nonhuman animals can estimate object numerosities—such as the number of sheep in a flock—without explicit counting. Here, we report on a negative time-order effect (TOE) in this type of judgment: When nonsymbolic numerical stimuli are presented sequentially, the second stimulus is overestimated compared to the first. We examined this “recent is more” effect in two comparative judgment tasks: larger–smaller discrimination and same–different discrimination. Ideal-observer modeling revealed evidence for a TOE in 88.2% of the individual data sets. Despite large individual differences in effect size, there was strong consistency in effect direction: 87.3% of the identified TOEs were negative. The average effect size was largely independent of task but did strongly depend on both stimulus magnitude and interstimulus interval. Finally, we used an estimation task to obtain insight into the origin of the effect. We found that subjects tend to overestimate both stimuli but the second one more strongly than the first one. Overall, our findings are highly consistent with findings from studies on TOEs in nonnumerical judgments, which suggests a common underlying mechanism.

National Category
Psychology
Identifiers
urn:nbn:se:uu:diva-317321 (URN)10.1037/xhp0000387 (DOI)000402759300004 ()
Funder
Swedish Research Council
Available from: 2017-03-13 Created: 2017-03-13 Last updated: 2017-08-30Bibliographically approved
Van den Berg, R., Anandalingam, K., Zylberberg, A., Kiani, R., Shadlen, M. & Wolpert, D. (2016). A common mechanism underlies changes of mind about decisions and confidence. eLIFE
Open this publication in new window or tab >>A common mechanism underlies changes of mind about decisions and confidence
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2016 (English)In: eLIFE, E-ISSN 2050-084XArticle in journal (Refereed) Accepted
Abstract [en]

Decisions are accompanied by a degree of confidence that a selected option is correct. A sequential sampling framework explains the speed and accuracy of decisions and extends naturally to the confidence that the decision rendered is likely to be correct. However, discrepancies between confidence and accuracy suggest that confidence might be supported by mechanisms dissociated from the decision process. Here we show that this discrepancy can arise naturally because of simple processing delays. When participants were asked to report choice and confidence simultaneously, their confidence, reaction time and a perceptual decision about motion were explained by bounded evidence accumulation. However, we also observed revisions of the initial choice and/or confidence. These changes of mind were explained by a continuation of the mechanism that led to the initial choice. Our findings extend the sequential sampling framework to vacillation about confidence and invites caution in interpreting dissociations between confidence and accuracy.

National Category
Psychology (excluding Applied Psychology)
Identifiers
urn:nbn:se:uu:diva-275322 (URN)10.7554/eLife.12192 (DOI)
Available from: 2016-02-02 Created: 2016-02-02 Last updated: 2017-11-30Bibliographically approved
Van den Berg, R., Zylberberg, A., Kiani, R., Shadlen, M. N. & Wolpert, D. M. (2016). Confidence Is the Bridge between Multi-stage Decisions. Current Biology
Open this publication in new window or tab >>Confidence Is the Bridge between Multi-stage Decisions
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2016 (English)In: Current Biology, ISSN 0960-9822, E-ISSN 1879-0445Article in journal (Refereed) Published
Abstract [en]

Demanding tasks often require a series of decisions to reach a goal. Recent progress in perceptual decision-making has served to unite decision accuracy, speed, and confidence in a common framework of bounded evidence accumulation, furnishing a platform for the study of such multi-stage decisions. In many instances, the strategy applied to each decision, such as the speed-accuracy trade-off, ought to depend on the accuracy of the previous decisions. However, as the accuracy of each decision is often unknown to the decision maker, we hypothesized that subjects may carry forward a level of confidence in previous decisions to affect subsequent decisions. Subjects made two perceptual decisions sequentially and were rewarded only if they made both correctly. The speed and accuracy of individual decisions were explained by noisy evidence accumulation to a terminating bound. We found that subjects adjusted their speed-accuracy setting by elevating the termination bound on the second decision in proportion to their confidence in the first. The findings reveal a novel role for confidence and a degree of flexibility, hitherto unknown, in the brain’s ability to rapidly and precisely modify the mechanisms that control the termination of a decision.

Keywords
decision-making, confidence, decision bound, speed-accuracy trade-off, sequential choice, psychophysics, reaching, sensorimotor control
National Category
Psychology (excluding Applied Psychology)
Identifiers
urn:nbn:se:uu:diva-308828 (URN)10.1016/j.cub.2016.10.021 (DOI)
Available from: 2016-11-30 Created: 2016-11-30 Last updated: 2017-11-29Bibliographically approved
Bhardwaj, M., Van den Berg, R., Ma, W. J. & Josić, K. (2016). Do people take stimulus correlations into account in visual search?. PLoS ONE, 11(3), Article ID e0149402.
Open this publication in new window or tab >>Do people take stimulus correlations into account in visual search?
2016 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 11, no 3, article id e0149402Article in journal (Refereed) Published
Abstract [en]

In laboratory visual search experiments, distractors are often statistically independent of each other. However, stimuli in more naturalistic settings are often correlated and rarely independent. Here, we examine whether human observers take stimulus correlations into account in orientation target detection. We find that they do, although probably not optimally. In particular, it seems that low distractor correlations are overestimated. Our results might contribute to bridging the gap between artificial and natural visual search tasks.

National Category
Psychology (excluding Applied Psychology)
Identifiers
urn:nbn:se:uu:diva-275324 (URN)10.1371/journal.pone.0149402 (DOI)000371993000013 ()26963498 (PubMedID)
Available from: 2016-02-02 Created: 2016-02-02 Last updated: 2017-11-30Bibliographically approved
Thibault, L., Van den Berg, R., Cavanagh, P. & Sergent, C. (2016). Retrospective Attention Gates Discrete Conscious Access to Past Sensory Stimuli. PLoS ONE, 11(2), Article ID e0148504.
Open this publication in new window or tab >>Retrospective Attention Gates Discrete Conscious Access to Past Sensory Stimuli
2016 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 11, no 2, article id e0148504Article in journal (Refereed) Published
Abstract [en]

Cueing attention after the disappearance of visual stimuli biases which items will be remembered best. This observation has historically been attributed to the influence of attention on memory as opposed to subjective visual experience. We recently challenged this view by showing that cueing attention after the stimulus can improve the perception of a single Gabor patch at threshold levels of contrast. Here, we test whether this retro-perception actually increases the frequency of consciously perceiving the stimulus, or simply allows for a more precise recall of its features. We used retro-cues in an orientation-matching task and performed mixture-model analysis to independently estimate the proportion of guesses and the precision of non-guess responses. We find that the improvements in performance conferred by retrospective attention are overwhelmingly determined by a reduction in the proportion of guesses, providing strong evidence that attracting attention to the target’s location after its disappearance increases the likelihood of perceiving it consciously.

National Category
Psychology (excluding Applied Psychology)
Identifiers
urn:nbn:se:uu:diva-288991 (URN)10.1371/journal.pone.0148504 (DOI)
Available from: 2016-04-28 Created: 2016-04-28 Last updated: 2018-09-26Bibliographically approved
Ma, W. J., Shen, S., Dziugaite, G. & van den Berg, R. (2015). Requiem for the max rule?. Vision Research, 116(Pt B), 179-193
Open this publication in new window or tab >>Requiem for the max rule?
2015 (English)In: Vision Research, ISSN 0042-6989, E-ISSN 1878-5646, Vol. 116, no Pt B, p. 179-193Article in journal (Refereed) Published
Abstract [en]

In tasks such as visual search and change detection, a key question is how observers integrate noisy measurements from multiple locations to make a decision. Decision rules proposed to model this process have fallen into two categories: Bayes-optimal (ideal observer) rules and ad-hoc rules. Among the latter, the maximum-of-outputs (max) rule has been the most prominent. Reviewing recent work and performing new model comparisons across a range of paradigms, we find that in all cases except for one, the optimal rule describes human data as well as or better than every max rule either previously proposed or newly introduced here. This casts doubt on the utility of the max rule for understanding perceptual decision-making.

National Category
Psychology (excluding Applied Psychology)
Identifiers
urn:nbn:se:uu:diva-308838 (URN)10.1016/j.visres.2014.12.019 (DOI)25584425 (PubMedID)
Available from: 2016-11-30 Created: 2016-11-30 Last updated: 2017-11-29Bibliographically approved
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