Perceptual processing modes in the functional visual field

Abstract

Twelve subjects took part in an experiment requiring a same-different response to two simultaneously presented signals subtending a binocular visual angle of either 10°, 45° or 100°. Signals were either dot columns with four or five elements or the digits 4 and 5. Signal pairs could consist of two dot columns, two digits, a dot column and a digit (from the left to right), or a digit and a dot column, tested in separate blocks. The results show that the total fixation times between presentation and response were only shorter in the 10° than in the 45° condition when the signal pair consisted of two dot columns. This argues against the generality of Sanders' (1963) stationary field-eye-field distinction. The result is interpreted as evidence that two dot columns can be recoded into a new percept when they are sufficiently adjacent, but not when they are further apart. At 100°, fixation times were always much longer than at 45°, irrespective of the type of signal pair. This is consistent with a shift in processing mode between eye- and head-field as suggested by Sanders (1963).