TEXTURE SEGREGATION AND VISUAL-SEARCH - A COMPARISON OF THE EFFECTS OF RANDOM VARIATIONS ALONG IRRELEVANT DIMENSIONS

The effects of irrelevant variations in the color and depth of element s on participants' ability to detect and discriminate elements defined by a difference in orientation were compared. Consistent with previou s research, it was found that there was no effect or small effects if the targets were single elements in visual search tasks and that there were large effects for targets defined by several elements defining a n area in visual segmentation tasks. it is suggested that the reason f or the discrepancy between the 2 paradigms lies in the need for groupi ng processes in segmentation experiments. This notion was examined in 3 additional experiments that manipulated grouping processes through t ask demands and stimulus design. The data provide tentative support fo r this notion.