Abstract
Degrading real-world scenes in the central or the peripheral visual field yields a characteristic pattern: mean saccade amplitudes increase with central and decrease with peripheral degradation. Does this effect reflect a mere adaptation of the saccadic system to the changed visual conditions or modulations of selective attention? If saccade amplitudes reflect attentional modulation, the observed pattern predicts more focused attention in the central region with peripheral degradation and an attentional bias toward the periphery with central degradation. To investigate whether the amplitude pattern reflects attention, we measured the detectability of peripheral (Experiment 1) or central targets (Experiment 2) during scene viewing when low or high spatial frequencies were gaze-contingently filtered in the central or the peripheral visual field. Target detectability was matched between full-field filter condition by use of an adaptive threshold technique. Relative to an unfiltered control condition, peripheral filtering induced a decrease of the detection probability for peripheral, but not for central targets (tunnel vision). Central filtering decreased the detectability of central, but not of peripheral targets. Additional post-hoc analyses comparing polar distributions of target detection probability as a function of target-saccade angle and filtered region are compatible with the interpretation that saccade amplitudes and direction are computed in partial independence. In conclusion, the present experimental results strongly indicate that saccade amplitudes reflect attentional modulations.
Meeting abstract presented at VSS 2016