Aging and Temporal Patterns of Inhibition of Return

Journal of Gerontology: PSYCHOLOGICAL SCIENCES 2007, Vol. 62B, No. 2, P71–P77 Copyright 2007 by The Gerontological Society of America Aging and Temporal Patterns of Inhibition of Return Linda K. Langley,1 Luis J. Fuentes,2 Ana B. Vivas,3 and Alyson L. Saville1 1 Department of Psychology and Center for Visual Neuroscience, North Dakota State University, Fargo. 2 Departamento de Psicologı́a Básica y Metodologı́a, Universidad de Murcia, Spain. 3 Department of Psychology, City Liberal Studies, Affiliated Institution of the University of Sheffield, Thessaloniki, Greece. P EOPLE rely on spatial attention to locate goal-relevant items in the visual environment, and it is important to understand the cognitive mechanisms that underlie this ability. For example, how is it that searched locations are mentally tagged so as to prevent unnecessary reexamination? Posner and Cohen (1984) proposed that inhibition plays an important role in this tagging function. In the context of a spatial orienting study, they observed that a peripheral visual event (e.g., brightening of one of two boxes) was followed by a facilitated processing of items presented at that location, presumably as a result of a reflexive shift of attention toward the event. This facilitation occurred if the target item appeared within 300 ms of the orienting event. However, if attention was shifted either extrinsically by a visual event occurring elsewhere (e.g., brightening of a central cue) or intrinsically by a long time interval that brought attention back to fixation, an inhibitory aftereffect could be measured in terms of a delayed responding to items subsequently presented at the initial location. Posner and Cohen thought that this inhibition of return (IOR) effect functioned to bias attention toward novel locations, and Klein (1988) later proposed that IOR served to discourage reinspections during visual search, thus increasing search efficiency. Consistent with a search interpretation, subsequent studies have provided evidence that observers do indeed use inhibition when navigating complex search scenes (Klein, 1988; Klein & MacInnes, 1999; Kristjansson, 2000). Reduced inhibitory control may account, at least in part, for age-related changes in search performance. Older adults are generally slower and more distractible than young adults during visual search, particularly on inefficient tasks that require effortful, sequential search through the display (Foster, Behrmann, & Stuss, 1995; Humphrey & Kramer, 1997; Plude & Doussard-Roosevelt, 1989). Although there is evidence that sensory changes and generalized cognitive slowing contribute to changes in search (Madden, 2001; Scialfa, 1990), attentionspecific factors such as inhibition also likely contribute to it. Consistent with this idea, recent studies have found age-related changes in the time course of IOR (Castel, Chasteen, Scialfa, & Pratt, 2003; Langley, Fuentes, Hochhalter, Brandt, & Overmier, 2001). In the following sections, we review findings relevant to the timing characteristics of IOR and age differences in these effects. Time Course of IOR How quickly does IOR develop at a location, and how long does it last? In a recent graphical meta-analysis, Samuel and Kat (2003) addressed these questions by plotting IOR scores as a function of cue–target stimulus onset asynchrony (SOA) for studies that used a single peripheral cue (i.e., there was no central cue to extrinsically redirect attention toward fixation). Inhibited rather than facilitated orienting responses to the cued location were reliably observed as early as 300 ms and were maintained as long as 1,500 ms. However, there were few data points beyond 1,500 ms; follow-up experiments indicated that inhibitory effects lasted somewhere between 2 and 3 s. Other research has found that although inhibition can remain at a particular location for as long as 5 s (Berlucchi, Chelazzi, & Tassinari, 2000; Danziger, Kingstone, & Snyder, 1998), the magnitude of IOR declines with increasing cue–target interval (Berlucchi et al.; Klein, 2000; Riggio, Bello, & Umilta, 1998). This temporal decline would be optimal for aiding search performance if inhibition were a limited resource; inhibition would be strongest for the most recently searched locations, and inhibition would diminish for earlier searched locations to free up resources for newly inspected sites. Studies using multiple cues have found just such a pattern; IOR could be maintained at multiple locations, but inhibition diminished in magnitude for earlier cued locations (Dodd, Castel, & Pratt, 2003; Snyder & Kingstone, 2000). Support for the idea that inhibition is resource limited can also be found in studies that report reduced negative priming (a nonspatial form of distractor inhibition) under resource-demanding conditions (Engle, Conway, Tuholski, & Shisler, 1995; Neumann & DeSchepper, 1992). Tasks Demands and Timing of IOR Inhibitory effects are robust on IOR tasks that require the simple detection of objects, but initial studies to examine IOR on tasks that require discrimination of target features P71 Inhibition of return (IOR), an inhibitory component of spatial attention that is thought to bias visual search toward novel locations, is considered relatively well preserved with normal aging. We conducted two experiments to assess age-related changes in the temporal pattern of IOR. Inhibitory effects, which were strongly reflected in the performance of both younger adults (ages 18–34 years) and older adults (ages 60–79 years), diminished over a period of 5 s. The time point at which IOR began to diminish was delayed by approximately 1 s for older adults compared with younger adults; this pattern was observed on both a target detection task (Experiment 1) and a color discrimination task (Experiment 2). The finding that timing characteristics of IOR are altered by normal aging has potential implications for the manner in which inhibition aids search performance. P72 LANGLEY ET AL. Aging and Temporal Patterns of IOR Among studies that have examined age differences in the temporal patterns of IOR, in their study, Castel and colleagues (2003) found that the time point at which IOR first develops is delayed with age. On a single-cue IOR task, the cue–target SOA at which facilitated responses turned to inhibition was 222 ms for younger adults and 592 ms for older adults. Similar to the detection–discrimination explanation already described, the interpretation offered by Castel and colleagues was that the agerelated delay in inhibition was due to task difficulty. Because older adults found the detection task more difficult than younger adults did, they allocated more attention for a longer duration to cued locations, delaying the onset of IOR. Most research described to this point has used a single-cue IOR task. Another widely used IOR paradigm is the cue-back task, in which a second central cue reflexively draws attention back to fixation. T (...truncated)