Cookies on this website

We use cookies to ensure that we give you the best experience on our website. If you click 'Accept all cookies' we'll assume that you are happy to receive all cookies and you won't see this message again. If you click 'Reject all non-essential cookies' only necessary cookies providing core functionality such as security, network management, and accessibility will be enabled. Click 'Find out more' for information on how to change your cookie settings.

Within-dimension conjunction search for red-green targets amongst red-blue, and blue-green, nontargets is extremely inefficient (Wolfe et al, 1990 Journal of Experimental Psychology: Human Perception and Performance 16 879-892). We tested whether pairs of red-green conjunction targets can nevertheless be processed spatially in parallel. Participants made speeded detection responses whenever a red-green target was present. Across trials where a second identical target was present, the distribution of detection times was compatible with the assumption that targets were processed in parallel (Miller, 1982 Cognitive Psychology 14 247-279). We show that this was not an artifact of response-competition or feature-based processing. We suggest that within-dimension conjunctions can be processed spatially in parallel. Visual search for such items may be inefficient owing to within-dimension grouping between items.

Original publication




Journal article



Publication Date





49 - 60


Adult, Color Perception, Female, Form Perception, Humans, Male, Psychophysics