Abstract
Subitizing (with number of items less than or equal to 4) and estimation (with number of items equal to or larger than 5) are two types of strategies for rapid enumeration. Debate remains about the relationship between subitizing and estimation, and evidence is scarce from the tactile modality. The present study has developed a novel processing switching paradigm to assess costs in cognitive resources related to switching between the two processes. Participants were required to enumerate two sequentially presented arrays of tactile pins with the set size of each array either within or out of a predetermined subitizing range (1-3 tactile pins). We found a general task-dependent switch cost within a narrow temporal range- the first numerical processing significantly influenced the second numerical processing with stimuli-onset-asychrony (SOA) between the two events was 100 ms. Specifically, the error rate of the second enumeration increased, while the accuracy and the precision decreased, when the enumeration process switched between the two strategies (subitizing-estimation or estimation-subitizing), relative to no switch (subitizing-subitizing or estimation-estimation). At the same time, an asymmetry was observed on the accuracy and the precision— a switch from estimation to subitizing triggered a robust switch cost effect with larger magnitudes than a switch from subitizing to estimation did. Taken together, our results suggest that the relationship of subitizing and estimation in tactile modality is consistent with the findings in visual modality (Anobile et al., 2012; Burr et al., 2010). Specifically, there is an additional mechanism over and above the unitary estimation, manifests certain flexibility and only operates on small numerosities when attentional resources permit.