Browsing by Author "Altan, Ecem"

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Open Access
Size aftereffect is non-local
(Elsevier, 2020) Altan, Ecem; Boyacı, Hüseyin
It is well known that prolonged exposure to a certain size stimulus alters the perceived size of a subsequently presented stimulus at the same location. How the rest of the visual space is affected by this size adaptation, however, has not been systematically studied before. Here, to fill this gap in literature, we tested size adaptation at the adapter location as well as the rest of the visual space. We used peripherally presented solid discs (Experiment 1) and rings (Experiment 2) as adapter and target (test) stimuli. Observers adapted to a mid-sized stimulus and judged the size of the subsequently presented smaller or larger target stimuli. Results showed that the perceived sizes of target stimuli were repelled away from the adapter size, not only at the adapter location but also at other locations. These findings demonstrate that size adaptation causes widespread distortion of the visual space and alters perceived size. We discuss possible computational models that may underpin the perceptual effect.
Open Access
The spatial extent of size adaptation effect in peripheral vision
(2019-07) Altan, Ecem
It has been shown that prolonged exposure to a certain object size (i.e. size adaptation) alters the subsequent size perception such that the size of the latter appears more dissimilar to the adapted size (Pooresmaeili, Arrighi, Biagi, & Morrone, 2013). However, how much of the visual space is in uenced by the size adaptation at a certain location remains unanswered. Here, in order to investigate the spatial extent of the adaptation effect, we tested the size adaptation effect at the adapted location and various non-adapted locations. In the first psychophysical experiment, we showed a mid-sized adapter stimulus and tested its in uence on subsequent size perception at 5 locations. Results showed that the size perception at non-adapted locations was in uenced by the adapter, although not as much as the effect at the adapted location. In the second experiment, we tested the size aftereffect at 15 different locations and mapped out the perceived size distortions over the visual field. Lastly, in the third experiment, we tested the effect of size adaptation with ring-shaped stimuli and found a substantially large effect just as in the second experiment. These findings overall suggest that the size adaptation does not only have a local effect but also the size perception in consequence of adaptation is being distorted throughout the visual field.