Why doesn't emotional valence affect subitising and counting in simple enumeration?

Abstract

Accurate visual-spatial enumeration involves either the subitising process (for 1-4 items) or the counting process (for larger numbers of items). Although these processes differ, both are thought to involve attentional selection. Many studies show that emotional valence, the negativity or positivity of a stimulus, influences attention and yet Watson and Blagrove found valence had no effect on simple enumeration (enumeration without distractors). To shed light on this surprising finding, we had participants enumerate 1 to 9 dots after viewing emotional scenes, using images from the International Affective Picture System (IAPS) to manipulate valence and arousal. To ensure valence and arousal categorisations were valid for each participant, we individualised them based on their own ratings. Results indicated that both valence and arousal affected enumeration latencies, with enumeration fastest after positive high arousal images and slowest after negative low arousal images. Disengagement deficits were apparent from slowed enumeration after negative images, but there was no evidence that valence affected the breadth of the attentional focus (no interactions with display area). Despite hints that valence may affect subitising and counting differently (weak trends to a cross-over interaction in RT slopes), no firm conclusions can be made because differences were small (<20 ms/item).