Attentional biases in geometric form perception

This paper reports the operation of robust attentional bias to the top and right during perception of small, single geometric forms. Same/different ju dgements of successively presented standard and comparison forms are faster when local differences are located at top and right rather than in other r egions of the forms. The bias persists when form size is reduced to approxi mately one degree of visual angle, and it is unaffected by saccadic eye mov ements and by instructions to attend to other reliably differentiating regi ons of the forms. Results lend support in various degrees to two of the pos sible explanations of the bias: (1) a static, skewed distribution of attent ional resources around eye fixation; and (2) biased, covert scanning that c ommences invariably at the top and right of stimulus forms. Origins of the bias in terms of possible left-hemispheric capacity for constructing repres entations of visual stimuli from parts, as well as in terms of reading expe rience and prevailing optic flow during locomotion through space are consid ered. Recent investigations of conditions under which the bias can be maint ained or reduced are mentioned.