相互相関計算に基づく奥行き知覚は刺激間距離により減弱する

 

上平田蓉子1、小賀智文2、青木 俊太郎2、藤田一郎1,2,3

 

1大阪大学 基礎工学部

2大阪大学大学院 生命機能研究科

3大阪大学・情報通信研究機構 脳情報通信融合研究センター

 

A gap between adjacent surfaces deteriorates depth perception based on binocular correlation computation

 

Hiroko Kamihirata1, Tomofumi Oga2, Shuntaro C. Aoki2, Ichiro Fujita1,2,3

1School of Engineering Science, 2Graduate School of Frontier Biosciences, Osaka Univ

3Center for Information and Neural Networks, Osaka Univ/NICT

 

The visual system computes depth from binocular disparity. The initial encoding of disparity is achieved by computing cross-correlation between left-eye and right-eye images. When luminance contrast of either image is reversed (binocularly anti-correlated), neurons signaling the cross-correlation show inverted disparity tuning. It remains elusive whether the correlation-based signals are exploited by the brain to produce depth perception. We previously showed that anti-correlated stereograms (aRDSs) evoke reversed depth, suggesting that the brain does use the signals (Tanabe et al., 2008). However, Hibbard et al. (2014) found no reversed depth for stimuli that had a gap between a patch and its surround but were otherwise similar to ours. Here we examined effects of a gap between the two surfaces on reversed depth. Subjects were shown a concentric-bipartite RDS and reported whether the center patch was nearer or farther than the annular surround. The patch was either a contrast-matched RDS (cRDS) or an aRDS with crossed or uncrossed disparities, while the surround was always a cRDS at 0 disparity. Most subjects (8 out of 12) perceived reversed depth for aRDS patches with a gap of <0.175 deg. Reversed depth diminished as the gap became wider, and disappeared when a gap was 0.7 deg wide. A small gap thus profoundly affected reversed depth, suggesting that correlation-based depth signals are integrated over a spatially limited range of visual field.  (COI:NO)

 

 keywords: 認知神経科学、視覚