Effects of spatial distribution of attention during inhibition of return (IOR) on flanker interference in hearing and congenitally deaf people.

This study explored the interaction between the spatial distribution of attention during inhibition of return (IOR) and different levels of flanker interference in congenitally deaf subjects as compared with hearing subjects. Color (Experiment 1) and alphanumeric (Experiment 2) flanker interference effects were differentiated into the pre-response and the response levels. The spatial distribution of attention was manipulated through IOR. Subjects were asked to either make color or letter/digit discriminations to the central targets or detect the abrupt-onset peripheral targets. Deaf subjects were significantly faster than hearing subjects at detecting peripheral targets irrespective of the cue validity, while the two groups had comparable sizes of IOR. In the central discrimination tasks, deaf subjects showed significant response level, but not pre-response level, flanker effects irrespective of the type of stimuli and the spatial location of the flanker. For hearing subjects, however, spatial attention interacted with the pre-response and response flanker effects in different ways. While flankers at the cued location caused interference effects at the response level and facilitatory effects at the pre-response level, those at the uncued location caused different effects depending on the type of stimuli. Moreover, increasing the peripheral attention for hearing subjects, by increasing the proportion of peripheral detection trials, made hearing subjects behave like deaf subjects. These results demonstrate that deaf people possess enhanced peripheral attentional resources as compared with hearing people. The spatial distribution of attention modulates mainly the resolution of the pre-response flanker interference in hearing people, but affects neither the pre-response nor the response level interference in deaf people.