Remote temporal camouflage: contextual flicker disrupts perceived visual temporal order.

Abstract

Correctly perceiving the temporal order of events is essential to many tasks. Despite this, the factors constraining our ability to make timing judgments remain largely unspecified. Here we present a new phenomenon demonstrating that perceived timing of visual events may be profoundly impaired by the mere presence of irrelevant events elsewhere in the visual field. Human observers saw two abrupt luminance events presented across a range of onset asynchronies. Temporal order judgment (TOJ) just noticeable differences (JNDs) provided a behavioural index of temporal precision. When target events were presented in isolation or in static distractor environments temporal resolution was very precise (JNDs ∼20ms). However, when surrounded by dynamic distractor events, performance deteriorated more than a factor of four. This contextual effect we refer to as Remote Temporal Camouflage (RTC) operates across large spatial and temporal distances and possesses a unique spatial distribution conforming to neither the predictions of attentional capture by transient events, nor by stimulus dependencies associated with other contextual phenomena such as surround suppression, crowding, object-substitution masking or motion-induced blindness. We propose that RTC is a consequence of motion-related masking whereby irrelevant motion signals evoked by dynamic distractors interfere with TOJ-relevant target-related apparent motion. Consistent with this we also show that dynamic visual distractors do not interfere with audio-visual TOJs. Not only is RTC the most spatially extensive contextual effect ever reported, it offers vision science a new technique with which to investigate temporal order performance, free of motion-related sensory contributions.