Abstract
Abstract: :
Purpose: Rapid serial visual presentation (RSVP) involves the sequential presentation of visual targets at one spatial location, usually at a rate of 10 or more letters/sec. Identification of one target (T1) in an RSVP stream results in a temporary reduction in the ability to identify subsequent targets. The period during which identification of subsequent targets is inhibited is called the attentional blink (AB). The aim of this experiment was to characterise the attentional blink in human amblyopes. Methods: Twenty adult subjects, ten amblyopes and ten age-matched controls, participated. Amblyopes were either strabismic, anisometropic, or aniso-strabismic. An RSVP stream of twenty individual letters was presented at a rate of 10.6 letters/sec. Nineteen of the letters were black and one, T1, was red. In 60% of the trials, one of the letters presented after T1 was the probe, a black "X." The subjects’ task was two-fold: (1) identify T1; and (2) determine if the probe was present in the stream of letters. The length and depth of the blink were calculated for each individual and again with the data collapsed across the group. Nonparametric analyses were used. Results: . Amblyopes demonstrated an AB that terminated 450-600 msec after T1 presentation, depending on the method of calculation. The control AB (nondominant eye) was 380-490 msec. The difference in AB length was not statistically significant between the two groups. Anisometropic amblyopes' AB differed from strabismic or anisostrabismic amblyopes' AB. Conclusions: The AB for amblyopes as a group was not statistically different from that of controls. The strabismic and aniso-strabismic amblyopes as a group did not demonstrate the usual improvement in target detection after the initial deficit in target detection. However, anisometropic amblyopes' AB was very similar to that of controls.
Keywords: amblyopia • attention