Academic journal article Psychonomic Bulletin & Review

Distraction as a Determinant of Processing Speed

Academic journal article Psychonomic Bulletin & Review

Distraction as a Determinant of Processing Speed

Article excerpt

Processing speed is often described as a fundamental resource determining individual (e.g., I.Q.) and group (e.g., developmental) differences in cognition. However, most tests that measure speed present many items on a single page. Because many groups with slowed responding are also distractible, we compared younger and older adults on high-distraction (i.e., standard) versus low-distraction versions of two classic speed tasks. Reducing distraction improved the performance of older adults but had little or no effect on younger adults, suggesting that the ability to limit attentional access to task-relevant information can affect performance on tests designed to measure processing speed.

The idea that "faster is better" is powerful in cars, computing, and cognitive psychology. Group differences, especially age differences, are often ascribed to the better performing group's faster processing. We report two experiments that assessed the contribution of an attentionalperceptual variable, visual distraction, in determining age differences in classic speed tasks.

Many standard speed tests use items that are individually simple but fit many such items onto a single page, resulting in a cluttered, potentially distracting display. Many groups thought to have deficits in processing speed also have difficulties regulating attention and thus might be especially vulnerable to distraction. These groups include children, older adults, poor readers, and young adults who score less well on intelligence tests (see, e.g., casey, Giedd, & Thomas, 2000; Dempster & Corkill, 1999; Engle, Tuholski, Laughlin, & Conway, 1999; Fry & Hale, 1996; Gernsbacher & Faust, 1991; Hasher & Zacks, 1988; Kail, 1993; Salthouse, 1996a, 1996b).

Our interest in distraction's potential role in tests of processing speed stems from a long-standing theoretical framework emphasizing inhibitory control mechanisms that, together with goals, determine what information enters the focus of attention (e.g., Hasher & Zacks, 1988; Hasher, Zacks, & May, 1999). Weakened inhibitory control allows distraction to impede the speeded performance of older adults in other settings, including well-practiced skills such as reading (e.g., Carlson, Hasher, Connelly, & Zacks, 1995; Duchek, Balota, & Thessing, 1998; Dywan & Murphy, 1996; Madden, 1983; Rabbitt, 1965).

To assess distraction's potential role in tests of processing speed, we computerized two standard speed tasks and administered them to younger and older adults in one of two formats. The high-distraction format resembled the standard paper-and-pencil versions of these tasks, with many items presented at the same time. The low-distraction format reduced the opportunity for distraction by presenting items individually, so that only the currently relevant item was present on the screen.

Our hypothesis was simple: If vulnerability to distraction contributes to group differences in processing speed, older adults should be faster on the low-distraction versions of processing tests than on the high-distraction versions that resemble the standard, but distraction should make little difference to young adults.


The paper-and-pencil versions of the Letter Comparison and Pattern Comparison tasks (Salthouse & Babcock, 1991) are widely used as measures of processing speed (e.g., Hambrick & Oswald, 2005; Salthouse, 1993). Both meet our criteria for high distraction, with many items presented on a single page. We computerized the Letter Comparison task and presented it in either a high- or a low-distraction format. Correlations between the computerized Letter Comparison task and the standard paper-and-pencil version of the Pattern Comparison task were examined to ensure that the high-distraction computerized task was representative of performance on standard measures of processing speed.


Participants. Strict exclusionary criteria helped ensure that any differences were the result of age and our distraction manipulation, rather than extraneous problems with vision, health, or motor functioning. …

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