Temporal and Spatial Predictability of an Irrelevant Event Differently Affect Detection and Memory of Items in a Visual Sequence.

Junji Ohyama,Katsumi Watanabe

doi:10.3389/fpsyg.2016.00065

Abstract

We examined how the temporal and spatial predictability of a task-irrelevant visual event affects the detection and memory of a visual item embedded in a continuously changing sequence. Participants observed 11 sequentially presented letters, during which a task-irrelevant visual event was either present or absent. Predictabilities of spatial location and temporal position of the event were controlled in 2 × 2 conditions. In the spatially predictable conditions, the event occurred at the same location within the stimulus sequence or at another location, while, in the spatially unpredictable conditions, it occurred at random locations. In the temporally predictable conditions, the event timing was fixed relative to the order of the letters, while in the temporally unpredictable condition; it could not be predicted from the letter order. Participants performed a working memory task and a target detection reaction time (RT) task. Memory accuracy was higher for a letter simultaneously presented at the same location as the event in the temporally unpredictable conditions, irrespective of the spatial predictability of the event. On the other hand, the detection RTs were only faster for a letter simultaneously presented at the same location as the event when the event was both temporally and spatially predictable. Thus, to facilitate ongoing detection processes, an event must be predictable both in space and time, while memory processes are enhanced by temporally unpredictable (i.e., surprising) events. Evidently, temporal predictability has differential effects on detection and memory of a visual item embedded in a sequence of images.

Highlights

In our daily lives, countless visual changes around us occur in parallel; we only perceive or memorize some of these as salient events, and later recall fragmented event scenes that are abstracted from the important parts of ever-changing sequential information
With this dual predictability, when the events occurred in temporal conjunction with and at the same location as the target, the target detection speed was faster than it was for the target at the same timing but without the event
The results of Experiment 2 showed that when the occurrence of events was temporally predictable but spatially unpredictable, the events did not serve as cues for either memory or target detection processes

Summary

Introduction

Countless visual changes around us occur in parallel; we only perceive or memorize some of these as salient events, and later recall fragmented event scenes that are abstracted from the important parts of ever-changing sequential information. Attention plays an important role in identifying relevant spatio-temporal changes, and these salient changes might be perceived as an event. It has not yet been examined what types of visual changes. Schmidt et al (2002) reported that a visual change that was spatially congruent or incongruent in relation to the location of an array of items had a cueing effect on memory. They suggested that visual cues enhance memory of an item presented at the location of a cue. Previous studies have reported that salient visual change in context increases attention and influences later memory process of the events (Newtson and Engquist, 1976; Fabiani and Donchin, 1995; Hunt, 1995; Ranganath and Rainer, 2003; Swallow et al, 2009)

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Results

Conclusion