Attention drives human numerosity selective responses

Introduction Numerosity, the set size of a group items, helps guide behaviour and decisions. Previous studies have shown that neural populations respond selectively to numerosities. How numerosity is extracted from visual scene longstanding debate, often contrasting low-level with high-level cognitive processes. Here, using 7T functional MRI, we investigate how attention influences selective responses. Method 4 participants took part in three experiments. In all experiments, stimuli consisted black white dots within same display, participants’ was focused on either or while detecting subtle shape change attended dot subset. Experiment1, systematically increased 1 7, decreased 26 20, keeping total constant at 27. summarized fMRI signals responding subset’s population receptive field modelling (Dumoulin & Wandell, 2008). experiments2, used 2x2 block design establish response preferred, but unattended The subset consisting 2/3/4 (the preferred numerosities) were presented being unattended, respectively. fixed 40 non-preferred numerosities varied 36-38. Experiment 3 only one 20 shown, as result, varied. responses experiments 2-3 analysed general linear models. Results We found numerosity-tuned when their numerosity, irrespective Without attention, inhibited. Conclusions Unlike traditional effects cortex where enhances already existing responses, our results suggest required drive