Eyewitness lineups are typically composed of a suspect (guilty or innocent) and fillers (known innocents). Meta-analytic techniques were used to investigate the extent to which manipulations of suspectfiller similarity influenced identification decisions. Compared with lineups with moderate or high similarity fillers, lineups with low similarity fillers were far more likely to elicit suspect identifications. This was true regardless of whether the suspect was guilty or innocent, underscoring the importance of ensuring the suspect does not stand out from the fillers. Although whether the lineup contained moderate or high similarity fillers had no reliable influence on guilty suspect identifications, a higher rate of innocent suspect misidentifications was found for moderate similarity lineups. The correspondence between the meta-analytic findings and current lineup construction recommendations is discussed.

The authors manipulated stimulus contrast and response-stimulus interval in the alternating runs paradigm to investigate whether early processing could be carried out during a task switch. Subjects alternated between judging the magnitude and the parity of a digit. The results suggested that early processing was not carried out during the task switch (Experiment 1), even in the absence of potentially confounding auditory or visual warning signals (Experiment 2). This processing was, however, carried out in parallel with a demanding operation in a 2nd task (Experiment 3), using the display parameters of Experiments 1 and 2 in the psychological refractory period paradigm. It is concluded that, functionally, task switching may impose a hard bottleneck even for very early stimulus processing. ((c) 2003 APA, all rights reserved)

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Research suggests that subjects can compute the mean size of two sets of interspersed objects concurrently, but that doing so incurs a cost of dividing attention across the two sets. Alternatively, costs may arise from failing to exclude irrelevant items from the calculation of mean size. Here, we examined whether attention can be selectively deployed to prevent the inclusion of items from an irrelevant, concurrently displayed set in the computation of the relevant set's mean size. The results suggest that mean size is computed prior to the deployment of attention, failing to exclude processing of items that are irrelevant to the task. The influence of the irrelevant items is evident both with brief exposures of the set (200ms) and in a simultaneous judgment task with unlimited viewing time, suggesting that attention cannot be effectively deployed to facilitate selective averaging of the size of the relevant set. Size averaging appears to precede the deployment of selective attention, suggesting that it may be carried out automatically, without intention.

Eyewitness lineups typically contain a suspect (guilty or innocent) and fillers (known innocents). The degree to which fillers should resemble the suspect is a complex issue that has yet to be resolved. Previously, researchers have voiced concern that eyewitnesses would be unable to identify their target from a lineup containing highly similar fillers; however, our literature review suggests highly similar fillers have only rarely been shown to have this effect. To further examine the effect of highly similar fillers on lineup responses, we used morphing software to create fillers of moderately high and very high similarity to the suspect. When the culprit was in the lineup, a higher correct identification rate was observed in moderately high similarity lineups than in very high similarity lineups. When the culprit was absent, similarity did not yield a significant effect on innocent suspect misidentification rates. However, the correct rejection rate in the moderately high similarity lineup was 20% higher than in the very high similarity lineup. When choosing rates were controlled by calculating identification probabilities for only those who made a selection from the lineup, culprit identification rates as well as innocent suspect misidentification rates were significantly higher in the moderately high similarity lineup than in the very high similarity lineup. Thus, very high similarity fillers yielded costs and benefits. Although our research suggests that selecting the most similar fillers available may adversely affect correct identification rates, we recommend additional research using fillers obtained from police databases to corroborate our findings.

In this article, we will investigate the question of whether comparisons of number magnitude require central processing resources. Carrier and Pashler (1995) have argued that retrieval from long-term (episodic) memory cannot be carried out in parallel with response selection in another task, because both operations require access to a single, capacity-limited central process. Logan and Schulkind (2000), however, have argued that retrieval of information from long-term (semantic) memory for responding to one stimulus could be carried out in parallel with retrieval from semantic memory for another stimulus, as long as the same task set was applied to both stimuli. In their Experiment 2, subjects were presented with two digits at varying stimulus onset asynchronies (SOAs) and were asked to perform the same task for each digit (two magnitude judgments or two parity judgments) or different tasks (a magnitude judgment for one digit and a parity judgment for the other). When the task sets applied to the digits were the same, responses to the first stimulus were faster with a match between the categorization of the second stimulus and the categorization of the first stimulus than when the two categorizations did not match. That is, there was crosstalk between the processing of the two digits. When different task sets were applied to the two stimuli, however, no effect of category compatibility was observed for responses to the first stimulus (i.e., there was no crosstalk between Tasks 1 and 2). Logan and Schulkind argued that number magnitude information was not automatically retrieved from long-term memory in parallel with another task but, rather, was retrieved only when the same task set could be applied to both stimuli.This conclusion of Logan and Schulkind (2000) seems inconsistent with a large body of research in the area of number processing, which suggests that information about digit magnitude is processed autonomously-that is, whether it is relevant to the task at hand or not. Henik and Tzelgov (1982) found that when subjects were asked to compare the physical size of two digits, determining which digit was physically larger was faster when the physically larger digit was also numerically larger than the digit with which it was compared. In addition, Dehaene and Akhavein (1995) found that more errors were made in judging two stimuli as physically nonidentical when the quantities represented by the two stimuli were equal (e.g., two and 2) than when they were unequal (e.g., two and 4). Furthermore, Windes (1968) showed that the time to report the number of symbols present in a display was shorter when the symbols were, for example, three plus signs than when they were three ones (see also Fox, Shor, & Steinman, 1971). Taken together, the available evidence strongly suggests that information about a digit's magnitude is accessed whether this information is task relevant or not, and even when it is deleterious to performance. Furthermore, the tasks described above did not require information about number magnitude...

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Previous research suggests that sets of similar items are represented using a rapid averaging mechanism that automatically extracts statistical properties within 50 ms. However, typically in these studies, displays are not masked, so it is possible that the sets are available for longer than this duration. In the present study, using masked displays, we (a) tested a newly proposed strategy for extracting the mean size of a set of circles, and (b) more precisely evaluated the time course of rapid averaging. The results indicate that when viewing conditions are poor, performance can be explained by assuming that observers rely on information from previous trials. In this study, observers required at least a 200-ms exposure time in order to derive the average size of a set of circles without relying on information from previously-viewed sets, suggesting that rapid averaging is not as fast as previously assumed and, therefore, that it may not be an automatic process.When shown a set of similar items, people can rapidly summarize the set according to statistical properties, such as the mean size. Ariely (2001) found that observers were able to determine the average size of a set of circles, but were unable to identify individual members of the set. Ariely interpreted this as evidence that the visual system can derive a statistical representation of the set without retaining specific information about the items within the set. Researchers have proposed that this is accomplished using a specialized averaging mechanism that evaluates all of the items in the set in parallel. Consistent with this proposal, Chong and Treisman (2005a) showed that averaging performance was better when attention was broadly distributed across a display than when attention was narrowly focused, suggesting that the specialized averaging mechanism operates preattentively, outside the focus of attention. Additional evidence for the automaticity of this process has been demonstrated through cuing and dual-task manipulations.