Effects of context on visual temporal order judgments in RSVP

Abstract

A combined rapid serial visual presentation (RSVP) and temporal order judgement paradigm was developed to study the role of task and context in visual temporal order perception. Participants had to identify an event specified by its order as well as another feature (report the first white symbol in a sequence). The assumption that some additional information introduced into a context can change perception of temporal order was tested. Participants reported the first of two white digits following each other within an RSVP stream of black character distractors (100 ms per item). In some trials luminance of items was constant within each subset of items (black and white). On other trials a black item either preceding or following the white items was slightly brighter (less black) than the other distractors. Still other trials included a small difference in the luminance of the white digits. Trials of all types were intermixed. The luminance manipulation significantly affected performance, although it remained unnoticed by the subjects. When the two white digits were of the same luminance, false reports of the second white digit were not significantly different from correct reports of the first digit. When either the first white digit or the preceding or following distractor was highlighted, more correct responses than false reports of the second item were observed. Highlighting of the second white item had no significant effect on temporal order performance. The fact that the following distractor produced the same effect (more accurate responses) as the preceding distractor rules out a processing speed benefit from a luminance/contrast change as the explanation of the context effect revealed in the present study. Other explanations will be discussed. More results obtained with temporal order judgement in the RSVP paradigm will also be presented.