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Yarden Gliksman, Avishai Henik; Alerting cues affect the subitizing process: Evidence from developmental and acquired dyscalculia . Journal of Vision 2014;14(10):546. doi: 10.1167/14.10.546.
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Enumeration of elements (e.g., dots) differs as a function of their range. Subitizing (1-4 dots) is considered to be an accurate and quick process with reaction times (RTs) minimally affected by the number of presented elements. In contrast, in counting (5-9 dots) RT rises additively as a function of the number of dots presented. Observations from previous studies led us to investigate whether subitizing is a global process: (a) the right-TPJ (temporo-parietal-junction) is related to both global processing and alertness (Lamb et al., 1990); (b) alertness enhanced global processing (Weinbach & Henik, 2011); (c) the right-TPJ was found to be activated in the subitizing range and inhibited in the estimation range (Ansari et al., 2007). Moreover, recently we demonstrated that alerting modulated RT only in the subitizing range (Gliksman & Henik, in preparation). In the current study, we explored effects of range (subitizing vs. counting) and alertness in participant with acquired dyscalculia (AD) due to left intraparietal sulcus damage, and in participants with developmental dyscalculia (DD). AD and DD are characterized as having mathematics difficulty. Our results indicated that in the subitizing range, an alerting cue prior to a target created faster RT for AD (the same as for controls) and expanded the subitizing range of DD participants (4 vs. 3). In counting range, AD participant presented an opposite alerting effect (i.e., trials with an alerting cue were processed slower) and DD participants presented a small or null effect for the alerting cue. Since the right and left hemispheres involve global and local processing, respectively, the pattern of results of AD are in line with our suggestion that subitizing is a global process while counting is a local process. For the DD participants, their smaller-than-normal subitizing range can be explained by low efficiency of global processing, which might improve with alerting.
Meeting abstract presented at VSS 2014
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