This study investigated the dynamic adjustment of the attention focusing in function of some physical characteristics of an exogenous visual cue. The first experiment investigated the effect of the area delimitated by a visual cue presented by different intervals between stimuli. The second experiment investigated the availability of attentional resources in the horizontal and vertical meridian of the visual field and the effect of flanking letters presented in and out of the attention focusing. The results of the first experiment suggest that the attention focusing may be kept stable for a period longer than 500 milliseconds and that the time through which the attention resources can remain stable is inversely proportional to their area. These results also corroborated an inverse relation between the size of the area to be fulfilled and the information processing efficiency. The results of the second experiment corroborated the effect caused by flanking letters observed by other authors (B. Ericksen & Ericksen, 1974; Miller, 1991) with an increase on the reaction time in the presence of the flanking letter incompatible with the target. Flanking letters have a significant smaller effect when presented out of the area delimitated by the visual cue. This result indicates an inhibitory attentional action out of the focusing area. Moreover, a possible asymmetry in the distribution of these inhibitory resources between the horizontal and vertical meridian of the visual field was also observed.
Visual attention; Attention focusing; Reaction time