When does repeated search in scenes involve memory? Looking at versus looking for objects in scenes

One might assume that familiarity with a scene or previous encounters with objects embedded in a scene would benefit subsequent search for those items. However, in a series of experiments we show that this is not the case: When participants were asked to subsequently search for multiple objects in the same scene, search performance remained essentially unchanged over the course of searches despite increasing scene familiarity. Similarly, looking at target objects during previews, which included letter search, 30 seconds of free viewing, or even 30 seconds of memorizing a scene, also did not benefit search for the same objects later on. However, when the same object was searched for again memory for the previous search was capable of producing very substantial speeding of search despite many different intervening searches. This was especially the case when the previous search engagement had been active rather than supported by a cue. While these search benefits speak to the strength of memory-guided search when the same search target is repeated, the lack of memory guidance during initial object searches-despite previous encounters with the target objects-demonstrates the dominance of guidance by generic scene knowledge in real-world search.     

Flexible cue combination in the guidance of attention in visual search

Hodsoll and Humphreys (2001) have assessed the relative contributions of stimulus-driven and user-driven knowledge on linearly- and nonlinearly separable searches. However, the target feature used to determine linear separability in their task (i.e., target size) was required to locate the target. In the present work, we investigated the contributions of stimulus-driven and user-driven knowledge when a linearly- or a nonlinearly-separable feature is available but not required for target identification. We asked observers to complete a series of standard color × orientation conjunction searches in which target size was either linearly- or nonlinearly separable from the size of the distractors. When guidance by color × orientation and guidance by size information are both available, observers rely on whichever information results in the best search efficiency. This is the case irrespective of whether we provide target foreknowledge by blocking stimulus conditions, suggesting that feature information is used in both a stimulus-driven and a user-driven fashion.     

I. The loving parent meets the selfish gene

In a recent Inquiry article Louis Pascal argues that the problem of massive starvation in the modern world is the result of a genetically‐based human propensity to produce as many offspring as possible, regardless of ecological conditions. In this paper biological and anthropological objections to Pascal's thesis are discussed as well as the conclusions he draws from it. It is suggested that natural selection has produced humans who are flexible in their reproductive behavior in order to cope with rapidly changing environments. The implications of both arguments for the population movement and the attempt to eliminate starvation are discussed.     

Psychometric Examination of the Brief Multidimensional Measure of Religiousness/Spirituality Among College Students

Resurgent interest in the relations between religiousness/spirituality (R/S) and health is evident in the scientific literature but much of the research fails to capture the proposed multidimensional nature of R/S. This problematic situation is compounded by the existence of a plethora of measures mostly lacking substantial empirical or even theoretical support. The Brief Multidimensional Measure of Religiousness/Spirituality (BMMRS) was developed to address measurement confusion by providing a standard instrument for researchers investigating the dimensions of R/S relevant to health. Psychometric properties and factor structure of the BMMRS were investigated in a sample of 374 college students. Exploratory and confirmatory factor analyses suggested a seven-factor structure for the BMMRS. Preliminary construct validity for the instrument was demonstrated. These findings generally support those of previous studies and suggest that the modified BMMRS is a viable multifactor measure of R/S for use with young adults.     

The gist of the abnormal: Above-chance medical decision making in the blink of an eye

Very fast extraction of global structural and statistical regularities allows us to access the “gist”—the basic meaning—of real-world images in as little as 20 ms. Gist processing is central to efficient assessment and orienting in complex environments. This ability is probably based on our extensive experience with the regularities of the natural world. If that is so, would experts develop an ability to extract the gist from the artificial stimuli (e.g., medical images) with which they have extensive visual experience? Anecdotally, experts report some ability to categorize images as normal or abnormal before actually finding an abnormality. We tested the reality of this perception in two expert populations: radiologists and cytologists. Observers viewed brief (250- to 2,000-ms) presentations of medical images. The presence of abnormality was randomized across trials. The task was to rate the abnormality of an image on a 0–100 analog scale and then to attempt to localize that abnormality on a subsequent screen showing only the outline of the image. Both groups of experts had above-chance performance for detecting subtle abnormalities at all stimulus durations (cytologists d' ≈ 1.2 and radiologists d' ≈ 1), whereas the nonexpert control groups did not differ from chance (d' ≈ 0.23, d' ≈ 0.25). Furthermore, the experts’ ability to localize these abnormalities was at chance levels, suggesting that categorization was based on a global signal, and not on fortuitous attention to a localized target. It is possible that this global signal could be exploited to improve clinical performance.     

Why does vantage point affect boundary extension?

To determine if layout affects boundary extension (BE; false memory beyond view boundaries; Intraub & Richardson, 1989), 12 single-object scenes were photographed from three vantage points: central (0°), shifted rightward (45°), and shifted leftward (45°). Size and position of main objects were held constant. Pictures were presented for 15 s each and were repeated at test with their boundaries: (a) displaced inward or outward (Experiment 1: N=120), or (b) identical to the stimulus views (Experiment 2: N=72). When participants adjusted test boundaries to match memory, BE always occurred, but tended to be smaller for 45° views. We propose this reflects the fact that more of the 3-D scene is visible in the 45° views. This suggests that scene representation reflects the 3-D world conveyed by the global characteristics of layout, rather than the 2-D distance between the main object and the boundaries of a picture.