Figure 1.

Search for the apple. A, In this display, searching for the apple can be reduced to searching for the unique item; this attentional set is called singleton detection mode. B, One cannot search for the unique item here but rather only for the features that define the target (feature search mode). C, Plot of simulated data based on Balan and Gottlieb (2006), their Figure 6a (http://www.jneurosci.org/cgi/content/full/26/36/9239#F6). Evoked responses to the singleton on −200 ms trials are plotted; the response is higher (by a multiplicative gain factor) during SAME blocks (SDM) compared with OPPOSITE blocks (FSM). In SDM, the multiplicative gain enhances the already robust response to the singleton, serving to further enhance the attentional priority of this location in the search array, which in turn may facilitate target localization.