A comparison of visual tilt illusions measured by the techniques of verticle setting, parallel matching, and dot alignment.

The tilt illusion (TI) was investigated by using both short (19 min) and long (2 deg 6 min) test lines, at three angles of test line-inducing line separation (15 degrees, 45 degrees, and 75 degrees). Three groups of ten observers each provided data under one of three task conditions: vertical judgment, parallel matching, and dot alignment on a common visual display. The main result was that both the vertical judgment and the parallel matching task provided similar, classic TI angular functions with the means ordered 15 degrees greater than 45 degrees greater than 75 degrees and with small attraction effects at 75 degrees in three of the four relevant functions. The third task, dot alignment, yielded results different from the average of the other two: no attraction effects occurred and, with the short test line, the obtained mean illusion at 45 degrees exceeded those at the other intersect angles. These results are consistent with alignment data reported by others. One explanation is that the inducing line produces an apparent bowing of the test line which would be reflected in dot alignments but not in vertical setting or in parallel matching. However, direct evidence does not support this hypothesis. An alternate hypothesis, for which independent evidence exists, is that alignment errors reflect perceptual mistracking but that the origin of these errors is not the tip of the test line but within it. Although this does not explain dot alignment errors, it highlights their complexity and the need to interpret them with caution.     

Lifestyle interventions in the treatment of childhood overweight: a meta-analytic review of randomized controlled trials.

CONTEXT: Evaluating the efficacy of pediatric weight loss treatments is critical. OBJECTIVE: This is the first meta-analysis of the efficacy of RCTs comparing pediatric lifestyle interventions to no-treatment or information/education-only controls. DATA SOURCES: Medline, PsycINFO, and Cochrane Controlled Trials Register. STUDY SELECTION: Fourteen RCTs targetting change in weight status were eligible, yielding 19 effect sizes. DATA EXTRACTION: Standardized coding was used to extract information on design, participant characteristics, interventions, and results. DATA SYNTHESIS: For trials with no-treatment controls, the mean effect size was 0.75 (k = 9, 95% confidence interval [CI] = 0.52-0.98) at end of treatment and 0.60 (k = 4, CI = 0.27-0.94) at follow-up. For trials with information/education-only controls, the mean ES was 0.48 (k = 4, CI = 0.13-0.82) at end of treatment and 0.91 (k = 2, CI = 0.32-1.50) at follow-up. No moderator effects were identified. CONCLUSIONS: Lifestyle interventions for pediatric overweight are efficacious in the short term with some evidence for extended persistence. Future research is required to identify moderators and mediators and to determine the optimal length and intensity of treatment required to produce enduring changes in weight status.     

Successive independence and behavioral contrast in a closed economy.

Two pigeons had access to multiple concurrent schedules of reinforcement for 24 hours per day in their home cages. The variable-interval schedules comprising the multiple concurrent schedules were varied across 16 conditions. In three sets of conditions, one schedule was varied while its concurrent alternative and the concurrent schedules in the other component were held constant. Behavioral contrast was observed; that is, as the rate of reinforcement arranged by the varied schedule decreased, response rates on the constant schedules typically increased. These conditions formed part of two larger sets of conditions in which the concurrent schedules in one multiple-schedule component remained constant while the concurrent schedules in the other component were varied. Successive independence was found, in that behavior allocation during the constant component did not vary as a function of the reinforcer ratios in the varied component. Successive independence between components in multiple concurrent schedules is a robust result that occurs in closed economies and under conditions that promote behavioral contrast.     

Semantic priming in young and older adults: evidence for age constancy in automatic and attentional processes

Automatic and attentional components of semantic priming and the relation of each to episodic memory were evaluated in young and older adults. Category names served as prime words, and the relatedness of the prime to a subsequent lexical decision target was varied orthogonally with whether the target category was expected or unexpected. At a prime-target stimulus-onset asynchrony (SOA) of 410 ms, target words in the same category had faster lexical decision latencies than did different category targets. This effect was not significant at a 1,550-ms SOA and was attributed to automatic processes. Expected category targets had faster latencies than unexpected category targets at the 410-ms SOA, and the magnitude of the effect increased at the 1,550-ms SOA. This effect was attributed to attentional processes. These patterns of priming were obtained for both age groups, but in a surprise memory test older adults had poorer recall of primes and targets. We discuss the implications of these results for the hypothesis that older adults suffer deficits in selective attention and for the related hypothesis that attentional deficits impair semantic processing, which causes memory decrements in old age.     

Influence of win-loss ratio on performance,satisfaction and preference for opponents

Hypotheses about the preference for opponents in competitive situations, about performance under various win-loss ratios, and about task and opponent satisfaction under various win-loss ratios were tested. A 5 × 5 latin square with four replications and a repeated measure factor of trials was the design used with 20 female college students as subjects. The five different win percents were W₁₀, W₃₀, W₅₀, W₇₀, and W₉₀. A manipulative maze task was used with subjects receiving 20 trials against each of five confederate opponents. Results indicated that (a) when a person knows little or nothing about her ability level she initially prefers to compete with opponents of low ability but with each subsequent contest opponents of higher ability levels are preferred; (b) subjects performed better in the W₅₀ condition; (c) task satisfaction is higher when the percent of wins is equal to or greater than the percent of losses; and (d) opponent satisfaction is greater for opponents who perform equal to or better than the subject.