The effects of cross-sensory attentional demand on subitizing and on mapping number onto space

Various aspects of numerosity judgments, especially subitizing and the mapping of number onto space, depend strongly on attentional resources. Here we use a dual-task paradigm to investigate the effects of cross-sensory attentional demands on visual subitizing and spatial mapping. The results show that subitizing is strongly dependent on attentional resources, far more so than is estimation of higher numerosities. But unlike many other sensory tasks, visual subitizing is equally affected by concurrent attentionally demanding auditory and tactile tasks as it is by visual tasks, suggesting that subitizing may be amodal. Mapping number onto space was also strongly affected by attention, but only when the dual-task was in the visual modality. The non-linearities in numberline mapping under attentional load are well explained by a Bayesian model of central tendency.

► We investigated the effects of attention on subitizing and spatial mapping of number. ► The results show that subitizing is strongly dependent on attentional resources. ► Visual subitizing was affected by concurrent auditory, tactile and visual tasks. ► Mapping number was affected by visual, but not auditory attention. ► The effect of attention on number mapping is explained by Bayesian central tendency.