Optimal Predictions in Everyday Cognition: The Wisdom of Individuals or Crowds?

Griffiths and Tenenbaum (2006) asked individuals to make predictions about the duration or extent of everyday events (e.g., cake baking times), and reported that predictions were optimal, employing Bayesian inference based on veridical prior distributions. Although the predictions conformed strikingly to statistics of the world, they reflect averages over many individuals. On the conjecture that the accuracy of the group response is chiefly a consequence of aggregating across individuals, we constructed simple, heuristic approximations to the Bayesian model premised on the hypothesis that individuals have access merely to a sample of k instances drawn from the relevant distribution. The accuracy of the group response reported by Griffiths and Tenenbaum could be accounted for by supposing that individuals each utilize only two instances. Moreover, the variability of the group data is more consistent with this small-sample hypothesis than with the hypothesis that people utilize veridical or nearly veridical representations of the underlying prior distributions. Our analyses lead to a qualitatively different view of how individuals reason from past experience than the view espoused by Griffiths and Tenenbaum.     

Rabbis and Health: A Half-Century Review of the Mental and Physical Health Care Literature:1950–1999

Electronic searches were conducted on PubMed and the American Psychological Association's database (PsycINFO) for articles that discussed the role of rabbis in relation to some aspect of healthcare. The two searches were conducted in each electronic database using the search-terms: (1) (rabbi OR rabbinical OR synagogue) OR (2) (Judaism OR Jewish) AND (clergy OR chaplain). Articles were classified by the year of their publication, professional discipline, type of journal (either religious or secular), and type of article: either research, or narrative and expositional. Rabbis were discussed most often in psychology, psychiatry, and behavior-related fields, and close to two-thirds of the articles dealt with mental health concerns. A statistically significant increase in articles across decades was found in the secular journals, r=.98, p≤.01, with over 70% of the articles about rabbis in the secular journals being published between 1980 and 1999. Many of the articles addressed collaboration between rabbis, psychiatrists, and other and mental health professionals and discussed previously identified themes related to professional collaboration and referral.     

The Validity of Verifiable and Non‐verifiable Biodata Items: An Examination Across Applicants and Incumbents

This study examines the influence of item verifiability (non‐verifiable vs. verifiable), context (applicant vs. incumbent), and keying procedure on biodata mean test scores and validity. Concurrent and predictive validation studies were conducted using a sample of 425 call center incumbents and a sample of 410 call center applicants. Although applicants did not obtain significantly higher mean biodata scores, results provide support for the hypothesis that the non‐verifiable biodata composite would be less valid in the applicant context, while the verifiable biodata composite would be equally valid across both the applicant and incumbent contexts. The same pattern of results was obtained using both item‐ and option‐keying procedures. Implications for research and practice are discussed.     

The hollow-face illusion: object-specific knowledge, general assumptions or properties of the stimulus?

The hollow-face illusion, in which a mask appears as a convex face, is a powerful example of binocular depth inversion occurring with a real object under a wide range of viewing conditions. Explanations of the illusion are reviewed and six experiments reported. In experiment 1 the detrimental effect of figural inversion, evidence for the importance of familiarity, was found for other oriented objects. The inversion effect held for masks lit from the side (experiment 2). The illusion was stronger for a mask rotated by 90 degrees lit from its forehead than from its chin, suggesting that familiar patterns of shading enhance the illusion (experiment 2). There were no effects of light source visibility or any left/right asymmetry (experiment 3). In experiments 4-6 we used a 'virtual' hollow face, with illusion strength quantified by the proportion of noise texture needed to eliminate the illusion. Adding characteristic surface colour enhanced the illusion, consistent with the familiar face pigmentation outweighing additional bottom-up cues (experiment 4). There was no difference between perspective and orthographic projection. Photographic negation reduced, but did not eliminate, the illusion, suggesting shading is important but not essential (experiment 5). Absolute depth was not critical, although a shallower mask was given less extreme convexity ratings (experiment 6). We argue that the illusion arises owing to a convexity preference when the raw data have ambiguous interpretations. However, using a familiar object with typical orientation, shading, and pigmentation greatly enhances the effect.     

Direction-of-motion discrimination is facilitated by visible motion smear

Recent evidence indicates that motion smear can provide useful information for the detection and discrimination of motion. Further, it has been shown that the perception of motion smear depends critically on the density of dots in a random-dot (RD) stimulus. Therefore, in the present experiments, the contribution of perceived motion smear to direction-of-motion discrimination was evaluated using RD targets of different densities. Thresholds for direction-of-motion discrimination and the extent of perceived motion smear were determined for RD stimuli with densities of 1, 2, and 10 dots/deg(2), presented for 200 msec at a velocity of 4, 8, or 12 deg/sec. To evaluate the contribution of information about orientation from motion smear, thresholds for orientation discrimination were measured using parallel lines with the same length as the extent of perceived smear. Despite the opportunity for increased summation as RD density increases, our results indicate that direction-of-motion discrimination worsens. Because perception of motion smear is reduced with an increase in RD density, our results are consistent with a facilitation of direction-of-motion discrimination by visible motion smear.     

Priming of semantic classifications by novel subliminal prime words

Four experiments demonstrate category congruency priming by subliminal prime words that were never seen as targets in a valence-classification task (Experiments 1, 2, and 4) and a gender-classification task (Experiment 3). In Experiment 1, overlap in terms of word fragments of one or more letters between primes and targets of different valences was larger than between primes and targets of the same valence. In Experiments 2 and 3, the sets of prime words and target words were completely disjoint in terms of used letters. In Experiment 4, pictures served as targets. The observed subliminal priming effects for novel primes cannot be driven by partial analysis of primes at the word-fragment level; they suggest instead that primes were processed semantically as whole words contingent upon prime duration.     

Testing beyond words: Using tests to enhance visuospatial map learning

Psychological research shows that learning can be powerfully enhanced through testing, but this finding has so far been confined to memory tasks requiring verbal responses. We explored whether testing can enhance learning of visuospatial information in maps. Fifty subjects each studied two maps, one through conventional study, and the other through computer-prompted tests. For the tests, the subjects were repeatedly presented with the same map with one feature deleted (e.g., a road or a river), and they tried to covertly recall the missing feature and its location. Subjects’ map drawings after 30 min were significantly better for maps learned through tests in comparison with maps learned through the same amount of time devoted to conventional study. These results suggest that the testing effect is not limited to the types of memory that require discrete, verbal responses, and that utilizing covert retrievals may allow the effect to be extended to a variety of complex, nonverbal learning tasks.     

Enhancing learning and retarding forgetting: Choices and consequences

Our research on learning enhancement has been focusing on the consequences for learning and forgetting of some of the more obvious and concrete choices that arise in instruction, including questions such as these: How does spacing of practice affect retention of information over significant retention intervals (up to 1 year)? Do spacing effects generalize beyond recall of verbal materials? Is feedback needed to promote learning, and must it be immediate? Although retrieval practice has been found to enhance learning in comparison with additional study, does it actually reduce the rate of forgetting? Can retrieval practice effects be extended to nonverbal materials? We suggest that as we begin to find answers to these questions, it should become possible for cognitive psychology to offer nonobvious advice that can be applied in a variety of instructional contexts to facilitate learning and reduce forgetting.