TRACKING EARLY AND LATE STAGES OF INFORMATION-PROCESSING - CONTRIBUTIONS OF STARTLE EYEBLINK REFLEX MODIFICATION

Startle eyeblink modification was examined as a measure of information processing. College students were presented with tones of 5 and 7 s d uration of either high or low pitch, followed by startle-eliciting sti muli at lead intervals of 120, 2,000, 4,500, or 6,000 ms. Attention to tones was manipulated by instructing the task group to count the long er tones of either pitch. The no-task group had no instructed task. St artle eyeblink was inhibited at the short lead interval and facilitate d at the long lead intervals in both groups. The task group showed gre ater inhibition and facilitation during attended than during ignored t ones, indicating that early and late controlled processing was occurri ng. In the task group, the degree of facilitation appeared to reflect the degree of cognitive demands of the task. Startle eyeblink modifica tion may provide a sensitive measure of the nature and timing of stage s of processing in active and passive attentional conditions.