The spatial relationship between cues and targets mediates inhibition of return.

Abstract

Abstract Although inhibition of return (IOR) has been examined in a number of experimental circumstances, it is not known if the number of potential target locations affects the magnitude of the inhibition at a cued location. To investigate this issue, participants were randomly presented with displays of two, four, or six potential target locations in a typical IOR detection task. The findings indicated that number of target locations did not affect IOR and that RTs at uncued locations varied systematically as a function of the spatial relationship between the cued and uncued location. Resume Bien que l'inhibition du retour (IOR) ait ete etudiee dans differents contextes experimentaux, on ne sait pas si le nombre d'emplacements possibles des cibles a un effet sur l'importance de l'inhibition a un emplacement marque par un indice. Pour approfondir l'examen de la question, on a presente aux participants des series de 2, 4 ou 6 emplacements possibles de cibles dans le contexte d'une tache typique de detection IOR. Les resultats indiquent que le nombre d'emplacements des cibles n'influe pas sur l'inhibition du retour et que le temps de reponse, pour les emplacements sans indice, varie systematiquement en fonction de la relation spatiale entre les emplacements accompagnes et non accompagnes d'indices. A considerable amount of research has examined inhibition of return (IOR) since the discovery of the phenomenon by Posner and Cohen in 1984. Posner and Cohen found that targets were detected more slowly at locations that had previously been cued when the delay between the presentation of the cue and the target exceeded 300 ms. They coined the term IOR for the effect, referring to their original notion that attention was inhibited to return to previously attended locations. Presumably, this inhibition occurred to make visual or attentional searches more efficient by biasing attention toward novel locations and away from previously inspected locations. It is because of this implication that IOR has been a topic for researchers in visual attention for more than a decade. Despite the wealth of research that has been conducted on IOR, some basic questions regarding the inhibitory effect have remained unasked and, consequently, unanswered. One of these questions is: Does the number of potential target locations affect IOR? This is a pertinent question because studies that have examined IOR have used anywhere from two (e.g., Maylor, 1984) to eight (e.g., Wright & Richard, 1996) potential target locations. Without knowing whether the number of potential target locations does or does not affect IOR, it is difficult to examine and interpret the different inhibitory effects produced between various experimental conditions. In addition to the pragmatic reasons for examining the effect of various possible target locations on IOR, there are also theoretical reasons to suggest that the number of locations may, or may not, differently affect IOR. On the one hand, if IOR does reflect the output of an attentional mechanism that improves searches, one might expect that the number of locations where the target might potentially occur would have a negative influence on the magnitude of IOR. Assuming that some amount of attention is allocated to each target location placeholder in a display, larger number of placeholders should require a greater proportion of the available attentional resources. This leads to a situation in which the amount of inhibition might be expected to decrease with increasing numbers of potential target locations because it would become more difficult to keep track of novel and previously attended locations. On the other hand, it may be that previously attended locations are tagged with inhibitory tags that require relatively little cognitive overhead, making the number of potential target locations largely irrelevant. For example, Klein and Taylor (1994) suggested that IOR occurs when eye movements are planned, but not executed, toward a specific location. …