Processing load does not facilitate access to quantity in coding tasks

Abstract

The present study examines the extent to which quantity representations associated with Arabic numerals (e.g., 7) influence how these numbers are recognised. The existence of faster responses in perceptual tasks (e.g., are 5 and 9 the same? is the following stimuli the number 5?) when the numerical distance between digit pairs is greater has thus far been the main evidence in favour of the automaticity of access to quantity representations and, therefore, of the influence of top-down processes on digit recognition. However, recent studies have shown that when perceptual similarity between digits is included as a predictor, the distance effect ceases to be a valid predictor in tasks that analyse early visual processes such as encoding and identification, with distance being relevant only when the task is later and requires quantitative knowledge (e.g., which number is larger/smaller between 5 and 9?). By adding a new variable to the question, that of processing load, it has been found that quantity representations intervene in the identification stage but only when multiple stimuli appear. The present study asks whether increasing the processing load at the earliest stage of the perceptual process, encoding, also grants a role to numerical distance. Twenty participants were asked to decide whether two simultaneously presented digits were the same or different, this under two conditions: in the load condition digits were flanked by symbols, in the no-load condition only the two single-digits were presented. Results were similar in both load conditions: perceptual similarity was the only valid predictor. Although perceptual load caused an increase in overall response times, it did not modify the predictive value of similarity and numerical distance.