Effects of reducing frequency of intrinsic knowledge of results on the learning of a motor skill

The guidance hypothesis suggests too much knowledge of results during skill acquisition can be detrimental to long-term performance. Possibly, the learner becomes dependent on augmented KR and is unable to use intrinsic feedback. This study examined this hypothesis with three groups performing a golf putting task. One group received continuous KR about ball path and final location; the other groups were deprived of specific KR on 50% or 100% of the acquisition trials. As expected, the continuous KR group performed better during acquisition, but the KR-deprived groups performed better on delayed retention trials, especially when KR was absent.     

The role of visual attention in predicting driving impairment in older adults

This study evaluated the role of visual attention (as measured by the DriverScan change detection task and the Useful Field of View Test [UFOV]) in the prediction of driving impairment in 155 adults between the ages of 63 and 87. In contrast to previous research, participants were not oversampled for visual impairment or history of automobile accidents. Although a history of automobile accidents within the past 3 years could not be predicted using any variable, driving performance in a low-fidelity simulator could be significantly predicted by performance in the change detection task and by the divided and selection attention subtests of the UFOV in structural equation models. The sensitivity and specificity of each measure in identifying at-risk drivers were also evaluated with receiver operating characteristic curves.     

Thirty-something categorization results explained: selective attention, eyetracking, and models of category learning

An eyetracking study testing D. L. Medin and M. M. Schaffer's (1978) 5-4 category structure was conducted. Over 30 studies have shown that the exemplar-based generalized context model (GCM) usually provides a better quantitative account of 5-4 learning data as compared with the prototype model. However, J. D. Smith and J. P. Minda (2000) argued that the GCM is a psychologically implausible account of 5-4 learning because it implies suboptimal attention weights. To test this claim, the authors recorded undergraduates' eye movements while the students learned the 5-4 category structure. Eye fixations matched the attention weights estimated by the GCM but not those of the prototype model. This result confirms that the GCM is a realistic model of the processes involved in learning the 5-4 structure and that learners do not always optimize attention, as commonly supposed. The conditions under which learners are likely to optimize attention during category learning are discussed.     

Individual differences in the emergence of depressive symptoms in children and adolescents: a longitudinal investigation of parent and child reports

The authors address questions about the rate that depressive symptoms emerge, developmental and gender differences in this rate, and differences between parent and child estimates of this rate. In a 12-wave, cohort-sequential, longitudinal design, 1,570 children (Grades 4-11) and parents completed reports about children's depression. Cross-domain latent growth curve analysis revealed that (a) the rate of symptom growth varied with developmental level. (b) gender differences symptom growth preceded emergence of mean level gender differences, (c) the rate of symptom development varied with age, and (d) parent-child agreement about rate of symptom change was stronger than agreement about time-specific symptoms. The authors suggest that predictability of depressive symptoms varies with age and the dimension under investigation.     

Intact perception of biological motion in the face of profound spatial deficits: Williams syndrome

Williams syndrome (WS) is a rare genetic disorder that results in profound spatial cognitive deficits. We examined whether individuals with WS have intact perception of biological motion, which requires global spatial integration of local motion signals into a unitary percept of a human form. Children with WS, normal mental-age-matched children, and normal adults viewed point-light-walker (PLW) displays portraying a human figure walking to the left or right. Children with WS were as good as or better than control children in their ability to judge the walker's direction, even when it was masked with dynamic noise that mimicked the local motion of the PLW lights. These results show that mechanisms underlying the perception of at least some kinds of biological motion are unimpaired in children with WS. They provide the first evidence of selective sparing of a specialized spatial system in individuals with a known genetic impairment.     

A comparison of methods to test mediation and other intervening variable effects

A Monte Carlo study compared 14 methods to test the statistical significance of the intervening variable effect. An intervening variable (mediator) transmits the effect of an independent variable to a dependent variable. The commonly used R. M. Baron and D. A. Kenny (1986) approach has low statistical power. Two methods based on the distribution of the product and 2 difference-in-coefficients methods have the most accurate Type I error rates and greatest statistical power except in 1 important case in which Type I error rates are too high. The best balance of Type I error and statistical power across all cases is the test of the joint significance of the two effects comprising the intervening variable effect.     

Flank transparency: transparent filters seen in dynamic two-color displays

Flank transparency is the perception of a colored transparent filter evoked by apparent-motion displays containing as few as two colors. Displays of flank transparency contain a random array of line segments placed on a uniform background. Small flanks are added to the line segments if the segments fall in the interior of a moving virtual shape, such as a virtual disk. This leads to the perception of a colored transparent disk with well-defined boundaries moving over the array of lines. Current qualitative and quantitative models of luminance and color conditions for perceptual transparency do not account for flank transparency as they require displays containing at least three different colors.     

Perceptions of an old female eyewitness: is the older eyewitness believable?

Young adults rated an old female witness (82 years) to be less competent but more honest than a young female witness (28 years). The effect of age stereotyping on believability was assessed indirectly by using a variant of Loftus' misinformation paradigm. Regression analysis showed that the more competent a witness was perceived as being, the more influential was the misinformation she provided. This was true, however, only when the witness was young because the relatively lower competence of the old witness was associated with nonsignificant misinformation effects. These data suggest that negative beliefs associating incompetence with old age may compromise the believability of older eyewitnesses.     

The generic-viewpoint assumption and illusory contours

Visual images are ambiguous. Any image, or collection of images, is consistent with an infinite number of possible scenes in the world. Yet we are generally unaware of this ambiguity. During ordinary perception we are generally aware of only one, or perhaps a few of these possibilities. Human vision evidently exploits certain constraints--assumptions about the world and images formed of it--in order to generate its perceptions. One constraint that has been widely studied by researchers in human and machine vision is the generic-viewpoint assumption. We show that this assumption can help to explain the widely discussed fact that outlines of blobs are ineffective inducers of illusory contours. We also present a number of novel effects and report an experiment suggesting that the generic-viewpoint assumption strongly influences illusory-contour perception.