Global and local precedence: Selective attention in form and motion perception.

Abstract

This study explores the perception of stimuli at two levels: local parts and the wholes that comprise these parts. Previous research has produced contradictory results. Some studies (e.g., Pomerantz & Sager, 1975) show local precedence, in which the local parts are more difficult to ignore in selective attention tasks. Other studies (e.g., Navon, 1977) have shown the opposite effect, global precedence. The present five experiments trace the causes of this discrepancy by exploring the effects of the relative discriminabilities of the local and global levels of the stimuli and the differences between two different measures of selective attention, namely, Stroop-type interference (attributable to incongruity on the irrelevant dimension) and Garner-type interference (attributable to variability on the irrelevant dimension). The experiments also examine whether the precedence effects previously examined in form perception generalize to motion perception. The results show that (a) some cases of global precedence are due solely to the greater perceptual discriminability of the global level and thus demonstrate only that more discriminable stimuli are harder to ignore; (b) instances of both local and global precedence can be demonstrated for certain types of stimuli, even when the discriminabilities of their local and global levels have been equated; and (c) the Stroop and Garner measures of selective attention are not equivalent but instead measure different types of interference. In addition, a distinction is made between two fundamentally different types of part-whole relationships that exist in visual configurations, one based only on the positions of the parts (Type P) and one based also on the nature of the parts (Type N). Previous research has focused on Type P, which appears to be irrelevant to the broader questions of Gestalt and top-down effects in perception. It is concluded that bona fide cases of both local and global precedence have been amply documented but that no general theory can account for why or when these effects will appear until we better understand both the nature of part-whole relationships and the perceptual processes that are tapped by different measures of selective attention.

Configural processing in autism and its relationship to face processing

“…All else being equal, in normal subjects, the global letter is identified faster than the local letter, and conflicting information between the global and the local levels exerts asymmetrical global-to-local interference (Navon, 1977). We note that many parameters affect these findings including the length of the exposure duration (Navon, 1977;Paquet & Merikle, 1984), sparsity of local letters (Martin, 1979), foveal placement of the stimulus (Pomerantz, 1983) and spatial certainty (Lamb & Robertson, 1988;Navon, 2003). In addition, the blocked version of the task used here requires focused attention at either the global or local level rather than divided attention in which, within a block, identification can occur at either level.…”

Boundaries of Separability between Melody and Rhythm in Music Discrimination: A Neuropsychological Perspective

“…Thus, for her, the situation might actually be considered more like a Garner (1974) task than a Stroop task. In Garner's task, interference is inferred when variation on the irrelevant dimension cannot be ignored, and thus it differs from Stroop effects, which indicate to what extent the content of the irrelevant variations can be ignored (Pomerantz, 1983;Pomerantz et al, 1989). The fact that C.N.…”

On the nature of interactions between the past and the present.

“…This pattern--Garner interference, an effect of congruity, and gain only to dimensions correlated positivelyZ--has appeared repeatedly in tests of dimensional interaction (e.g., Clark & Brownell, 1976;Melara & Marks, 1990d;Pomerantz, 1983). It is the signature of what Melara and his colleagues (Melara & Marks, 1990d;Melara & O'Brien, 1990) call semantic crosstalk.…”