Biases In Auditory-spatial Attention Induced By Numbers In Short-term Memory.
Previous studies investigating interactions between spatial attention and numeric stimuli (see SNARC effect) have identified an attentional bias induced by numeric stimuli in accordance with a mental number line model of processing. This processing model attributes orienting effects induced by numeric stimuli to long-term memory structures, such as a left-to-right number system in a given culture. The present study aims to investigate long-term memory may modulate attentional biases induced by the contents in short-term memory. In other words, can simply thinking about number induce spatial biasing effects? In this study, dichotic listening is used to measure of spatial attention in the auditory modality. Subjects were given numeric items to retain in short term memory during the spatial attention task, and prompted to recall the numbers verbally after each trial. Factors of number magnitude, load size, interval size between numbers, and presentation order are analyzed in terms of their effect on auditory spatial orienting. Auditory spatial orienting is assessed through a measure of laterality index — a ratio of left/right ear responses indicating attention as allocated to the left or right side of space. Results demonstrated a clear influence of number magnitude and presentation order on auditory spatial attention, however these effects were highly variable depending on other factors present in each experiment. Overall, results suggest that in addition to SNARC based orienting responses, the orienting effects of items in short term memory on spatial attention may be influenced by novelty, interactions with language, and multiple neural mechanisms responsible for representing quantity information.