The human visual system averages speed information

Watamaniuk, Scott; Duchon, Andrew

doi:10.1016/0042-6989(92)90036-i

Cited by 217 publications

(135 citation statements)

References 14 publications

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“…Similarly, psychophysical studies could use analogous stimulus distributions to study speed mechanisms. By way of example, Watama- niuk and Duchon (35) found that observers tend to base speed judgements on changes in the mean dot speed rather than the median or mode speeds. It follows from our results that an algorithm that reads from a bank of speed-tuned mechanisms may offer a better estimate of speed perception than the mean physical speed of motion.…”

Section: Discussionmentioning

confidence: 99%

“…The few studies that have considered this question suggest that human observers exploit the statistical characteristics of stimuli to judge the direction and speed of global motion (31)(32)(33)(34)(35). Human perceptual judgments tend to coincide with the mean direction of a moving dot field when local dots directions are drawn from a uniform distribution with a restricted range (32).…”

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confidence: 99%

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Cortical pooling algorithms for judging global motion direction

Webb

Ledgeway

McGraw

2007

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

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Physiological studies suggest that decision networks read from the neural representation in the middle temporal area to determine the perceived direction of visual motion, whereas psychophysical studies tend to characterize motion perception in terms of the statistical properties of stimuli. To reconcile these different approaches, we examined whether estimating the central tendency of the physical direction of global motion was a better indicator of perceived direction than algorithms (e.g., maximum likelihood) that read from directionally tuned mechanisms near the end of the motion pathway. The task of human observers was to discriminate the global direction of random dot kinematograms composed of asymmetrical distributions of local directions with distinct measures of central tendency. None of the statistical measures of image direction central tendency provided consistently accurate predictions of perceived global motion direction. However, regardless of the local composition of motion directions, a maximum-likelihood decoder produced global motion estimates commensurate with the psychophysical data. Our results suggest that mechanism-based, read-out algorithms offer a more accurate and robust guide to human motion perception than any stimulus-based, statistical estimate of central tendency.human psychophysics ͉ MT/V5 ͉ read-out algorithms ͉ visual motion ͉ population coding

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Cortical pooling algorithms for judging global motion direction

Webb

Ledgeway

McGraw

2007

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

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“…This summary representation or statistic has been called an "ensemble feature." For example, laboratory experiments suggest that humans can represent with little effort the mean size (Ariely, 2001;Chong & Treisman, 2003;Im & Chong, 2009), general direction of motion (Watamaniuk & Duchon, 1992), general location or "centroid" (Alvarez & Oliva, 2008), and approximate number of items in a group (Halberda, Sires, & Feigenson, 2006), as well as the average emotion of faces in a crowd (Haberman & Whitney, 2009, 2010.…”

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confidence: 99%

The effects of sampling and internal noise on the representation of ensemble average size

Halberda

2012

Atten Percept Psychophys

111

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Increasing numbers of studies have explored human observers' ability to rapidly extract statistical descriptions from collections of similar items (e.g., the average size and orientation of a group of tilted Gabor patches). Determining whether these descriptions are generated by mechanisms that are independent from object-based sampling procedures requires that we investigate how internal noise, external noise, and sampling affect subjects' performance. Here we systematically manipulated the external variability of ensembles and used variance summation modeling to estimate both the internal noise and the number of samples that affected the representation of ensemble average size. The results suggest that humans sample many more than one or two items from an array when forming an estimate of the average size, and that the internal noise that affects ensemble processing is lower than the noise that affects the processing of single objects. These results are discussed in light of other recent modeling efforts and suggest that ensemble processing of average size relies on a mechanism that is distinct from segmenting individual items. This ensemble process may be more similar to texture processing.

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“…The extraction of the statistical properties of a set of items appears to be a robust process, and it applies to many stimulus dimensions, including orientation (e.g., Dakin & Watt, 1997;Parkes, Lund, Angelucci, Solomon, & Morgan, 2001), motion speed (e.g., Atchley & Andersen, 1995;Watamaniuk & Duchon, 1992), and motion direction (Williams & Sekuler, 1984). Moreover, the accuracy of judgments of mean size is almost as good as the accuracy of size judgments for a single item (Chong & Treisman, 2003).…”

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confidence: 99%

Attention modulates set representation by statistical properties

Fockert

Marchant

2008

Perception & Psychophysics

104

128

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Recent reports have claimed that observers show accurate knowledge of the mean size of a group of similar objects, a finding that has been interpreted to suggest that sets of multiple objects are represented in terms of their statistical properties, such as mean size (Ariely, 2001;Chong & Treisman, 2003, 2005a, 2005b. In the present study, we directed visual attention to a single set member and found that mean estimations were modulated according to the size of the attended item, regardless of whether size was the relevant search criterion (Experiment 1) or not (Experiment 2). These findings suggest that observers do not always accurately average together the entire set, and that instead the average is either biased by the features of the attended item, or based on a short-cut strategy of extracting the mean of a smaller subset.

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The human visual system averages speed information

Cited by 217 publications

References 14 publications

Cortical pooling algorithms for judging global motion direction

Cortical pooling algorithms for judging global motion direction

The effects of sampling and internal noise on the representation of ensemble average size

Attention modulates set representation by statistical properties

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