Attentional limits on the perception and memory of visual information.

Palmer, John

doi:10.1037/0096-1523.16.2.332

Cited by 195 publications

(316 citation statements)

References 55 publications

(84 reference statements)

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“…When collapsed across trials, the data comprise a mixture of these two trial types (solid line), weighted by the probability that the probed item was stored in memory. slots would be a rational strategy, and this sort of averaging is common in models of perception [8][9][10] . For both the slots1resources and slots1averaging models, s.d.…”

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confidence: 99%

Discrete fixed-resolution representations in visual working memory

Zhang

Luck

2008

Nature

1,557

159

2,791

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Limits on the storage capacity of working memory significantly affect cognitive abilities in a wide range of domains 1 , but the nature of these capacity limits has been elusive 2 . Some researchers have proposed that working memory stores a limited set of discrete, fixed-resolution representations 3 , whereas others have proposed that working memory consists of a pool of resources that can be allocated flexibly to provide either a small number of highresolution representations or a large number of low-resolution representations 4 . Here we resolve this controversy by providing independent measures of capacity and resolution. We show that, when presented with more than a few simple objects, human observers store a high-resolution representation of a subset of the objects and retain no information about the others. Memory resolution varied over a narrow range that cannot be explained in terms of a general resource pool but can be well explained by a small set of discrete, fixed-resolution representations.To separately measure the number of items stored in working memory and the precision of each representation, we used a shortterm recall paradigm 5,6 in which subjects report the remembered colour of a probed item by clicking on a colour wheel (Fig. 1a). If the probed item has been stored in working memory, the recalled value will tend to be near the original colour. If the probed item has not been stored, then the observer will have no information about the colour, and the responses should be random. These two types of trials are mixed together in the data (Fig. 1b), but the components can be recovered via standard estimation methods. This produces one parameter (P m ) representing the probability that the probed item was present in memory at the time of the probe and another parameter (s.d.) representing the precision of the representation when the cued item was present in memory.Experiment 1 (N 5 8) tested this model using set sizes of 3 or 6 coloured squares (Fig. 1c). s.d. did not vary significantly across set sizes (F , 1), whereas P m was approximately twice as great at set size 3 as at set size 6 (F (1,7) 5 761.26, P , 0.001). Our simple fixed-resolution model provided an excellent quantitative fit to the data, whereas a model in which all items are encoded could not fit the data (see Supplementary Notes). This result rules out the entire class of working memory models in which all items are stored but with a resolution or noise level that depends on the number of items in memory 5 . Control experiments demonstrated that these results cannot be explained by a lack of time to encode the items or by a lack of sensitivity, and additional analyses demonstrated that the observers remembered continuous colour values rather than colour categories (see Supplementary Notes).These results demonstrate that observers store a small number of representations with good precision. However, it is possible that performance is influenced both by a limited number of 'storage slots' and a limited pool of resources 7 . As an an...

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confidence: 99%

Discrete fixed-resolution representations in visual working memory

Zhang

Luck

2008

Nature

1,557

159

2,791

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“…For half a century, the study of short-term memory limitations has been dominated by a single hypothesis, namely that a fixed number of items can be held in memory and any excess items are discarded (2)(3)(4)(5). The alternative notion that short-term memory resource is a continuous quantity distributed over all items, with a lower amount per item translating into lower encoding precision, has enjoyed some success (6)(7)(8), but has been unable to account for the finding that humans often seem to make a random guess when asked to report the identity of one of a set of remembered items, especially when many items are present (9). Specifically, if resource were evenly distributed across items (6,10), observers would never guess.…”

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confidence: 99%

“…The alternative notion that short-term memory resource is a continuous quantity distributed over all items, with a lower amount per item translating into lower encoding precision, has enjoyed some success (6)(7)(8), but has been unable to account for the finding that humans often seem to make a random guess when asked to report the identity of one of a set of remembered items, especially when many items are present (9). Specifically, if resource were evenly distributed across items (6,10), observers would never guess. Thus, at present, no viable continuous-resource model exists.…”

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confidence: 99%

“…According to the classic item-limit (IL) model (4), a fixed number of items is kept in memory, and memorized items are recalled perfectly. In the equal-precision (EP) model (6,10), a continuous resource is evenly distributed across all items. The slots-plus-averaging (SA) model (9) acknowledges the presence of noise but combines it with the notion of discrete slots.…”

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Variability in encoding precision accounts for visual short-term memory limitations

Berg

Shin

Chou

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

522

806

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It is commonly believed that visual short-term memory (VSTM) consists of a fixed number of "slots" in which items can be stored. An alternative theory in which memory resource is a continuous quantity distributed over all items seems to be refuted by the appearance of guessing in human responses. Here, we introduce a model in which resource is not only continuous but also variable across items and trials, causing random fluctuations in encoding precision. We tested this model against previous models using two VSTM paradigms and two feature dimensions. Our model accurately accounts for all aspects of the data, including apparent guessing, and outperforms slot models in formal model comparison. At the neural level, variability in precision might correspond to variability in neural population gain and doubly stochastic stimulus representation. Our results suggest that VSTM resource is continuous and variable rather than discrete and fixed and might explain why subjective experience of VSTM is not all or none.T homas Chamberlin famously warned scientists against entertaining only a single hypothesis, for such a modus operandi might lead to undue attachment and "a pressing of the facts to make them fit the theory" (ref. 1, p. 840). For half a century, the study of short-term memory limitations has been dominated by a single hypothesis, namely that a fixed number of items can be held in memory and any excess items are discarded (2-5). The alternative notion that short-term memory resource is a continuous quantity distributed over all items, with a lower amount per item translating into lower encoding precision, has enjoyed some success (6-8), but has been unable to account for the finding that humans often seem to make a random guess when asked to report the identity of one of a set of remembered items, especially when many items are present (9). Specifically, if resource were evenly distributed across items (6, 10), observers would never guess. Thus, at present, no viable continuous-resource model exists.Here, we propose a more sophisticated continuous-resource model, the variable-precision (VP) model, in which the amount of resource an item receives, and thus its encoding precision, varies randomly across items and trials and on average decreases with set size. Resource might correspond to the gain of a neural population pattern of activity encoding a memorized feature. When gain is higher, a stimulus is encoded with higher precision (11,12). Variability in gain across items and trials is consistent with observations of single-neuron firing rate variability (13-15) and attentional fluctuations (16, 17).We tested the VP model against three alternative models (Fig. 1). According to the classic item-limit (IL) model (4), a fixed number of items is kept in memory, and memorized items are recalled perfectly. In the equal-precision (EP) model (6, 10), a continuous resource is evenly distributed across all items. The slots-plus-averaging (SA) model (9) acknowledges the presence of noise but combines it with the notion of ...

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“…However, setsize does not influence the decision process in partial discrimination tasks, because only one test item is matched to one of many study items. Palmer (1990) showed that the difference threshold increased with an increase in set size from one to four and concluded that only one item could be retained in fine detail, but at least four items could be retained with some fidelity.…”

Section: Stvm Of Contour Curvaturementioning

confidence: 99%

A Review of Capacity Limitation From Visual Perception to Short-Term Visual Memory of a Single Curved Contour

Sakai¹

2017

JPR

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This study reviewed the literature regarding capacity limitation in processing curvature from visual perception to short-term visual memory (STVM) for a single curved contour with multiple convex parts. Capacity limitation was defined in terms of both set-size effects and decay with a retention interval. The results of psychophysical experiments and simulations involving signal detection theory indicated that visual perception exhibited some capacity limitation, which was caused by attentional allocation rather than sensory activation. In contrast, both iconic memory and STVM showed entirely limited capacity. Decay in STVM lasted for up to a minute and was reduced via an increase in the duration of stimulus presentation. Variance in represented stimulus values was shown to cause STVM decay. Decisional confusion, rather than capacity limitation in perception and STVM, was a primary factor in the deterioration of recognition of complex curved contours. Only one contour could be retained in STVM with very high fidelity, but at least four objects could be retained in STVM with some degree of fidelity.STVM appeared to exhibit little decay for a simple curved contour with four convex parts.

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Attentional limits on the perception and memory of visual information.

Cited by 195 publications

References 55 publications

Discrete fixed-resolution representations in visual working memory

Discrete fixed-resolution representations in visual working memory

Variability in encoding precision accounts for visual short-term memory limitations

A Review of Capacity Limitation From Visual Perception to Short-Term Visual Memory of a Single Curved Contour

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