Anisotropy of perceived numerosity: Evidence for a horizontal–vertical numerosity illusion

Pecunioso, Alessandra; Petrazzini, Maria Elena Miletto; Agrillo, Christian

doi:10.1016/j.actpsy.2020.103053

Cited by 8 publications

(4 citation statements)

References 66 publications

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“…This pattern seems to differ from classic findings of heightened sensitivity along the horizontal meridian in studies of low-level visual acuity 19 – 21 . However, the pattern we observed could be related to the notion of an anisotropy of perceived space, by which subjects estimate spatially spread out magnitudes like line length 22 and numerosity 23 to be larger along the vertical axis. We anticipate this incidental observation to be of interest for vision- and numerical cognition scientists using similar stimuli.…”

Section: Resultsmentioning

confidence: 67%

Concurrent visual working memory bias in sequential integration of approximate number

Kang

Spitzer

2021

Sci Rep

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Previous work has shown bidirectional crosstalk between Working Memory (WM) and perception such that the contents of WM can alter concurrent percepts and vice versa. Here, we examine WM-perception interactions in a new task setting. Participants judged the proportion of colored dots in a stream of visual displays while concurrently holding location- and color information in memory. Spatiotemporally resolved psychometrics disclosed a modulation of perceptual sensitivity consistent with a bias of visual spatial attention towards the memorized location. However, this effect was short-lived, suggesting that the visuospatial WM information was rapidly deprioritized during processing of new perceptual information. Independently, we observed robust bidirectional biases of categorical color judgments, in that perceptual decisions and mnemonic reports were attracted to each other. These biases occurred without reductions in overall perceptual sensitivity compared to control conditions without a concurrent WM load. The results conceptually replicate and extend previous findings in visual search and suggest that crosstalk between WM and perception can arise at multiple levels, from sensory-perceptual to decisional processing.

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Section: Resultsmentioning

confidence: 67%

Concurrent visual working memory bias in sequential integration of approximate number

Kang

Spitzer

2021

Sci Rep

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“…Assimilation and contrast effects seem to operate also in the perception of the HV illusion: the ends of the vertical line are supposed to be closer to the boundary of the visual field, leading to an assimilation of its length to the boundary edges of the visual field. Instead, the ends of the horizontal line are supposed to be far from the boundary of the visual field, eliciting a contrast effect [28,29]. A reduced susceptibility to contrast effects, found in the Delboeuf illusion study [19], may have impacted the behaviour exhibited with the L-shape, thereby reducing underestimation of the horizontal line and nulling the illusory effect.…”

Section: Plos Onementioning

confidence: 99%

Two halves are less than the whole: Evidence of a length bisection bias in fish (Poecilia reticulata)

Santacà

Agrillo

2020

PLoS ONE

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The horizontal-vertical (HV) illusion is characterized by a tendency to overestimate the length of vertically-arranged objects. Comparative research is primarily confined to primates, a range of species that, although arboreal, often explore their environment moving along the horizontal axis. Such behaviour may have led to the development of asymmetrical perceptual mechanisms to make relative size judgments of objects placed vertically and horizontally. We observed the susceptibility to the HV illusion in fish, whose ability to swim along the horizontal and vertical plane permits them to scan objects' size equally on both axes. Guppies (Poecilia reticulata) were trained to select the longer orange line to receive a food reward. In the test phase, two arrays, containing two same-sized lines were presented, one horizontally and the other vertically. Black lines were also included in each pattern to generate the perception of an inverted T-shape (where a horizontal line is bisected by a vertical one) or an L-shape (no bisection). No bias was observed in the L-shape, which supports the idea of differential perceptual mechanisms for primates and fish. In the inverted Tshape, guppies estimated the bisected line as shorter, providing the first evidence of a length bisection bias in a fish species.

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“…Despite this it is the inner group that is perceived as more numerous. Note that the convex hull measures objective size; it is also known that perceived (subjective) size can affect numerosity, as illustrated in the context of the Ponzo illusion (Ponzo, 1928), the horizontal vertical illusion (Pecunioso et al, 2020) or in terms of changes of perceived size after adaptation (Zimmermann & Fink, 2016).…”

Section: Introductionmentioning

confidence: 99%

What the Solitaire illusion tells us about perception of numerosity

Bertamini

Guest

Contemori

et al. 2022

British J of Psychology

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In four experiments we investigated the Solitaire illusion. In this illusion, most observers see as more numerous a set of dots that forms a single central group, compared to dots on the outside of that group. We confirmed and extended the effect to configurations with much higher numerosity than the original and of various colours. Contrary to prediction, separating the two groups, so that they are presented side by side, reduced but did not abolish or reverse the illusion. In this illusion, therefore, neither total size of the region (area), not average distance of the elements has the expected effect. In Experiments 3 and 4 we eliminated the regularity of the pattern, by sampling 50% (Exp 3) or only a 10% (Exp 4) of the elements. These produces quasi-random configurations. For these configurations the bias for the inner groups was still present, and it was only eliminated when the groups were shown as separate. However, the effect never reversed (no bias for the outer group, despite its larger area). We conclude that the Solitaire illusion is evidence of a strong bias in favour of centrally located elements, a bias that can overcome other factors.

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Anisotropy of perceived numerosity: Evidence for a horizontal–vertical numerosity illusion

Cited by 8 publications

References 66 publications

Concurrent visual working memory bias in sequential integration of approximate number

Concurrent visual working memory bias in sequential integration of approximate number

Two halves are less than the whole: Evidence of a length bisection bias in fish (Poecilia reticulata)

What the Solitaire illusion tells us about perception of numerosity

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