A shift of attention may be necessary, but it is not sufficient, for the generation of the Simon effect

The Simon effect is the performance advantage for spatially corresponding, compared to non-corresponding, target-response ensembles when the location of the target is task irrelevant. In four experiments, we tested the predictions of the attention-shift account of the Simon effect. In all experiments, subjects made choice responses with respect to the identity of a central target that followed a spatially non-informative peripheral precue. The first experiment showed a Simon effect away from the precue when the precue was a go/no-go signal: responses to spatially non-corresponding precue-response pairs were faster than responses to spatially corresponding precue-response pairs. The results of the second experiment suggested that this “reverse” Simon effect was not due to inhibition. In the third experiment, a secondary working memory task required the encoding, and later recall, of “oddball” precues. Although the Simon effect was absent, larger Simon effects towards the precue (i.e., responses were faster to spatially corresponding, compared to non-corresponding, precue-response ensembles) were correlated with poorer performance on the memory task. In the last experiment, the identity of completely non-informative precues was congruent, incongruent, or unrelated to the identity of the target. With precues that were unrelated to the identity of the target, there was a Simon effect towards the precues. Conversely, the Simon effect occurred away from the precue when the identity of the precue was related to that of the target. The findings suggest that a shift of attention alone is not sufficient to produce the Simon effect. Rather, the shift of attention must originate from an intentionally defined object. The results are discussed within a framework that integrates the attention-shift and referential-coding hypotheses. Received: 2 December 1999 / Accepted: 23 March 2000     

Does selective attention influence the octave illusion?

The octave illusion occurs when each ear receives a sequence of tones alternating by one octave, but with different frequencies in each ear. Most listeners report a high pitch in one ear alternating with a low pitch in the opposite ear. Deutsch and Roll proposed an influential suppression model of the illusion in which the pitch is determined by ear dominance, while the location of this pitch is determined by high-frequency dominance. Deutsch later suggested that this unusual division between 'what' and 'where' mechanisms is facilitated by sequential interactions within the eliciting sequence. A recent study has raised doubts about the suppression model and the role of sequential interactions in the illusion (Chambers et al, 2002 Journal of Experimental Psychology: Human Perception and Performance 28 1288-1302). Here, we examined whether this previous null effect of sequential interactions may have arisen because of uncontrolled influences of selective attention. The results reveal no evidence of a link between selective attention and sequential interactions, thus consolidating doubts about the validity of the suppression model.     

Sex Differences in Social Support and Self-Efficacy Within a Recovery Community

This study examined similarities and differences in social support and self-efficacy for abstinence between women and men recovering from substance addiction. The sample consisted of 87 residents of Oxford House (OH) self-run, community-based recovery homes. Analyses revealed similarities between women and men in terms of the composition and utilization of support networks and abstinence self-efficacy. Also, for both sexes, length of residency in OH was significantly related to decreased social support for alcohol and drug use and increased self-efficacy for abstinence. However, multiple-group SEM analyses demonstrated that social support for alcohol/drug use fully mediated the link between length of residency and abstinence self-efficacy for women, but not for men. Findings suggest that the process of gaining self-efficacy to remain abstinent is distinct for women and men, and that social support plays a different role in women's recovery than it does in men's.     

Perceptual functions in prosopagnosia

Some patients with prosopagnosia may have an apperceptive basis to their recognition defect. Perceptual abnormalities have been reported in single cases or small series, but the causal link of such deficits to prosopagnosia is unclear. Our goal was to identify candidate perceptual processes that might contribute to prosopagnosia, by subjecting several prosopagnosic patients to a battery of functions that may be necessary for accurate facial perception. We tested seven prosopagnosic patients. Three had unilateral right occipitotemporal lesions, two had bilateral posterior occipitotemporal lesions, and one had right anterior-to-occipital temporal damage along with a small left temporal lesion. These lesions all included the fusiform face area, in contrast to one patient with bilateral anterior temporal lesions. Most patients had impaired performance on face-matching tests and difficulty with subcategory judgments for non-face objects. The most consistent deficits in patients with lesions involving the fusiform face area were impaired perception of spatial relations in dot patterns and reduced contrast sensitivity in the 4 to 8 cycles deg(-1) range. Patients with bilateral lesions were impaired in saturation discrimination. Luminance discrimination was normal in all but two patients, and spatial resolution was uniformly spared. Curvature and line-orientation discrimination were impaired in only one patient, who also had the most difficulty with more basic-level object recognition. We conclude that deficits in luminance, spatial resolution, curvature, line orientation, and contrast at low spatial frequencies are unlikely to contribute to apperceptive prosopagnosia. More relevant may be contrast sensitivity at higher spatial frequencies and the analysis of object spatial structure. Deficits in these functions may impair perception of subtle variations in object shape, and may be one mechanism by which the recognition defect in prosopagnosia can extend to other classes of object subcategorization.     

The effect of midazolam on implicit and explicit memory in category exemplar production and category cued recall

Transfer-appropriate processing theory (Roediger, Weldon, & Challis, 1989) proposes that dissociations between performance on explicit and implicit memory tests arise because these tests often rely on different types of information processing (e.g., perceptual processing vs conceptual processing). This perspective predicts that implicit and explicit memory tasks that rely primarily on conceptual processing should show comparable results, not dissociations. Numerous studies have demonstrated such similarities. It is, however, possible that these results arise from explicit memory contamination of performance on implicit memory tasks. To address this issue, an experiment was conducted in which participants were administered the sedative midazolam prior to study. Midazolam is known to create a temporary, but dense, period of anterograde amnesia. The effects of blocking stimulus materials by semantic category at study and generation at study were investigated on category exemplar production and category-cued recall. The results of this study demonstrated a dissociation of the effects of midazolam on category exemplar production and category-cued recall. Specifically, midazolam reduced the effect of blocking stimulus materials in category-cued recall, but not in category exemplar production. The differential effect of midazolam on explicit and implicit memory is at odds with transfer-appropriate processing theory and suggests that theories of memory must distinguish the roles of different types of conceptual processing on implicit and explicit memory tests.     

Visual skills in airport-security screening

Abstract— An experiment examined visual performance in a simulated luggage-screening task. Observers participated in five sessions of a task requiring them to search for knives hidden in x-ray images of cluttered bags. Sensitivity and response times improved reliably as a result of practice. Eye movement data revealed that sensitivity increases were produced entirely by changes in observers' ability to recognize target objects, and not by changes in the effectiveness of visual scanning. Moreover, recognition skills were in part stimulus-specific, such that performance was degraded by the introduction of unfamiliar target objects. Implications for screener training are discussed.     

Retrieval-induced forgetting occurs in tests of item recognition

Using the retrieval-practice paradigm (Anderson, R. A. Bjork, & E. L. Bjork, 1994), we tested whether or not retrieval-induced forgetting could be found in item recognition tests. In Experiment 1, retrieval practice on items from semantic categories depressed recognition of nonpracticed items from the same categories. Similar results were found in Experiment 2 in a more stringent source test for practiced, nonpracticed, and new items. These results conceptually replicate those of previous retrieval-induced forgetting studies done with cued recall (e.g., Anderson et al., 1994). Our findings are inconsistent with the hypothesis that item-specific cues during retrieval will eliminate retrieval interference in the retrieval-practice paradigm (Butler, Williams, Zacks, & Maki, 2001). We discuss our results in relation to other retrieval interference and inhibition effects in recall and recognition.     

Hebbian learning and development

Hebbian learning is a biologically plausible and ecologically valid learning mechanism. In Hebbian learning, 'units that fire together, wire together'. Such learning may occur at the neural level in terms of long-term potentiation (LTP) and long-term depression (LTD). Many features of Hebbian learning are relevant to developmental theorizing, including its self-organizing nature and its ability to extract statistical regularities from the environment. Hebbian learning mechanisms may also play an important role in critical periods during development, and in a number of other developmental phenomena.