Individuation of multiple targets during visual enumeration: New insights from electrophysiology

Multiple Object Individuation and Exact Enumeration

“…Specifically, the N2pc amplitudes were modulated by target numerosity in both the target only and target plus distracter conditions. The fact that the N2pc modulation was visible even when no distracters were presented on the target side reasonably dismisses the possibility that this pattern is exclusively related to distracter suppression and, in line with very recent findings (Ester et al, 2012;Pagano & Mazza, 2012;Mazza & Caramazza, 2011), indicates that this electrophysiological response reflects the functioning of a processing stage that is tightly associated with the exact computation of the relevant quantities. In particular, we propose that it reflects the selective and simultaneous individuation of a subset of target elements in the visual field by means of a mechanism that binds featural properties and locations.…”

“…By contrast, other recent studies on multiple targets presented among distracters (during multiple object tracking, see Drew & Vogel, 2008; or during exact enumeration, see Ester, Drew, Klee, Vogel, & Awh, 2012;Pagano & Mazza, 2012;Mazza & Caramazza, 2011) show that the amplitude of the N2pc is sensitive to target numerosity (when these are presented in one hemifield only), increasing up to approximately three to four elements. 1 However, given that distracters were always presented on the target side, it is not clear whether this response is directly involved in the individuation of target elements per se or whether it simply reflects the effort of separating the targets from distracters (for instance, by suppressing the irrelevant objects presented on the target side).…”

“…For this reason and differently from Ester et al (2012), we focused on small target quantities and crucially manipulated the presence of distracters in the target field within a single experiment. In doing this, we were also trying to reconcile the apparently contrasting results and interpretations from our group (i.e., Pagano & Mazza, 2012;Mazza & Caramazza, 2011) with those from Hyde andSpelke (2009, 2012). For this reason, we additionally focused on the N1 component.…”

Normative shifts of cortical mechanisms of encoding contribute to adult age differences in visual–spatial working memory

“…Attentional selection was quantified as the magnitude of the N2pc component, a well-established ERP component that reflects the focusing of attention onto multi-stimulus arrays. The N2pc reflects a process of object individuation, or more precisely, the attentional mechanism that forms temporal representations of distinct objects from multi-stimulus arrays (Ester et al, 2012;Mazza and Caramazza, 2011;Pagano and Mazza, 2012). Younger adults showed a clear N2pc component for the high-load memory condition (i.e., 3 targets), consistent with the account of attentional object individuation, and hence, more distinct target representation.…”

Mean emotion from multiple facial expressions can be extracted with limited attention: Evidence from visual ERPs

“…The N2pc was previously related 5 to "individuation", and has been found to be modulated in amplitude by set size manipulations in 6 the multiple objects tracking and enumeration tasks (Drew & Vogel, 2008;Ester et al, 2012;7 Mazza & Caramazza, 2011;Pagano & Mazza, 2012). These two tasks require early individuation,…”