Stereoscopic depth aftereffects without retinal position correspondence between adaptation and test stimuli

AbstractTo clarify whether stereo-slant aftereffects are independent of stimulated retinal position, two experiments compared the magnitude of aftereffects between the following two conditions: when the adaptation and test stimulus fell on (1) the same retinal position, and (2) on different retinal positions separated by 0.5°–20°. In Experiment 1, disc- or ring-shaped surface consisting of random-dots was presented at the central or peripheral visual fields. In Experiment 2, rectangular surface was presented at the upper or lower visual fields. After two minutes inspection of a random-dot stereogram depicting a ±30° slanted surface, the observer adjusted the slant of the test stimulus to appear fronto-parallel. The results of the experiments showed that significant aftereffects were observed similarly in both conditions. Moreover, the separation nor the stimulus shape scarcely affected the magnitude of the aftereffects. Based on these results we concluded that the depth processing mechanism which operates independently from the stimulated retinal position is responsible for the depth aftereffects we found

自閉症者における視覚の特異性と可塑性についての実験心理学的検討

金沢大学人間社会研究域本研究の目的は,自閉症者における視知覚・視覚認知様式を健常者と比較し,その特異性(ないしは特異性の不在)を明らかにすることであった.本年度は前年度に引き続き,ロッド・フレーム錯視(RFI)と呼ばれる錯視課題を用いて,自閉症者における「視覚的枠組み」の使用が健常者と異なるか否か検討した.実験の結果,RFIの錯視量について自閉症者と健常者の間に差は見られなかった.しかしながら,自閉症群内における錯視量のばらつきは健常者群内におけるばらつきよりも大きく,一部は錯視量が極端に小さいことがわかった.このことから,自閉症者の中には健常者とは異なり視覚的枠組みに依拠しない視覚認知を行う一群のある可能性が示唆された.この結果は,自閉症者における視知覚の特異性を明らかにした点で重要であるだけでなく,自閉症群内に視覚認知様式の異なるサブタイプが存在する可能性を示した点でも重要であると考えられる.また本研究では,自閉症者における視知覚の特異性が脳のどの領野における機能不全と関連するのかを明らかにすることを下位目標のひとつとして定めていた.このため,近赤外分光法(NIRS)用いて,視覚関連課題遂行中の脳の賦活を自閉症群と健常群で比較することを計画した・しかしNIRSはごく近年実用化に成功した脳イメージング法であり,本研究の課題に関連して信頼に足るデータが得られるか否かは不確かであった.そこで,予備的な実験として健常成人を被験者としてNIRSを用いた視覚関連脳領野の機能測定を行った.この結果得られたデータは既知の生理学的知見と合致し,NIRSが基礎科学的研究の実用に足る方法であることが示された.この結果は,NIRSを自閉症の研究に適用するための基礎を築いた点で重要であると考えられる.研究課題/領域番号:18730464, 研究期間(年度):2006 – 2007出典：「自閉症者における視覚の特異性と可塑性についての実験心理学的検討」研究成果報告書　課題番号18730464（KAKEN：科学研究費助成事業データベース（国立情報学研究所））（https://kaken.nii.ac.jp/ja/grant/KAKENHI-PROJECT-18730464/)を加工して作

形状弁別課題遂行による後側頭部のヘモグロビン濃度変化(日本基礎心理学会第24回大会,大会発表要旨)

金沢大学文学部心理学Abstracts of Presentatio

鏡映描写における頭部ヘモグロビン濃度の測定(日本基礎心理学会第24回大会,大会発表要旨)

金沢大学文学部心理学Abstracts of Presentatio

フリッカー刺激呈示時の後頭部のヘモグロビン濃度変化(日本基礎心理学会第24回大会,大会発表要旨)

金沢大学文学部心理学Abstracts of Presentatio

Looking to Score: The Dissociation of Goal Influence on Eye Movement and Meta-Attentional Allocation in a Complex Dynamic Natural Scene

Several studies have reported that task instructions influence eye-movement behavior during static image observation. In contrast, during dynamic scene observation we show that while the specificity of the goal of a task influences observers’ beliefs about where they look, the goal does not in turn influence eye-movement patterns. In our study observers watched short video clips of a single tennis match and were asked to make subjective judgments about the allocation of visual attention to the items presented in the clip (e.g., ball, players, court lines, and umpire). However, before attending to the clips, observers were either told to simply watch clips (non-specific goal), or they were told to watch the clips with a view to judging which of the two tennis players was awarded the point (specific goal). The results of subjective reports suggest that observers believed that they allocated their attention more to goal-related items (e.g. court lines) if they performed the goal-specific task. However, we did not find the effect of goal specificity on major eye-movement parameters (i.e., saccadic amplitudes, inter-saccadic intervals, and gaze coherence). We conclude that the specificity of a task goal can alter observer’s beliefs about their attention allocation strategy, but such task-driven meta-attentional modulation does not necessarily correlate with eye-movement behavior

Shrinkage in the apparent size of cylindrical objects

A novel illusion in apparent size is reported. We asked observers to estimate the width and depth of vertically oriented elliptic cylinders depicted with texture or luminance gradients (experiment 1), or the height of horizontally oriented elliptic cylinders depicted with binocular disparity (experiment 2). The estimated width or height of cylinders showed systematic shrinkage in the direction of the gradual depth change. The dissimilarity of 2-D appearance amongst our stimuli implies a large variation in spatial-frequency components and brightness contrasts, eliminating the possibility that these parameters contributed to the illusion. Also, the mechanism inappropriately triggered by pictorial depth cues (eg size scaling) may be irrelevant, because the illusion was obtained even when binocular disparity alone specified the shape of the cylinders. The illusion demonstrated here suggests that our visual system may determine the size of 3-D objects by accounting for their depth structures

Changes in hemoglobin concentration in the lateral occipital regions during shape recognition: a near-infrared spectroscopy study

By using near-infrared spectroscopy (NIRS), we measured the changes in the oxygenated and deoxygenated hemoglobin (oxy-Hb and deoxy-Hb, respectively) concentrations while performing visual tasks. We conducted experiments using two tasks: a shape recognition task and a position recognition task. It was found that the oxy-Hb concentration was substantially higher in the lateral occipital regions during shape recognition than during position recognition. The changes in the oxy-Hb concentration were considered to reflect the activation difference between the two tasks. No difference was observed in the oxy-Hb concentration during the memorization of shape and memorization of position. The deoxy-Hb concentration was different between the two tasks only when different stimuli were used but not when identical stimuli were used. In addition, it was suggested that the deoxy-Hb concentration is more sensitive to activation difference between the hemispheres and the activation at some regions. Measurements of the oxy-Hb and deoxy-Hb concentrations would reflect different aspects of cortical activations. The present results showed that measuring the oxy-Hb and deoxy-Hb concentrations separately can differentiate the activation of the regional cortical functions

Sensory deprivation: Visual experience alters the mental number line

Early studies on numeric cognition reported that numbers are spatially organised according to a left-to-right small-to-large ‘number line’. We investigated whether this spatial-number organisation is dictated by visual experience. We tested congenitally and late blind, and blindfolded sighted participants in a random number generation task where in one block their heads were alternately turned left or right before uttering the number. We found that the ‘random’ number generation was biased according to the side where the head was turned to. Consistent with the standard number line, participants with visual experience generated smaller numbers for left turns, and larger numbers for right turns. In contrast, participants without any visual experience showed the opposite pattern of results. These results suggest a role for visual experience in the development of spatial and numerical representations, which is supported by cultural differences in number representation, and provide converging evidence for visually driven organisation of the parietal cortex

Depth adaptation and aftereffects

1．はじめに 2．奥行き残効とは 3．低次過程における順応 4．高次過程における順応 5．段階的順応モデル 6．モデルの生理学的裏付け 7．結 びProlonged inspection of a stimulus in a 3-D space produces an aftereffect in the depth dimension. This paper has two aims: (1) to review the previous studies on the depth aftereffects focusing on the level at which adaptation occurs, and (2) to propose a new model of the depth aftereffects. Conventionally, the depth aftereffects have been explained by adaptation of the lower level mechanisms specialized to each depth cue (e.g. ,binocular disparity or monocular depth cue) . However, recent studies suggest that the depth aftereffects are due to adaptation of the higher level mechanisms sensitive to 3-D shape rather than that of the lower level mechanisms. Author proposes a new model integrating both the conventional- and the recent theories