The ability of children to delay gratification in an exchange task

The ability to wait for a reward is a necessary capacity for economic transactions. This study is an age-related investigation of children's ability to delay gratification in an exchange task requiring them to wait for a significant reward. We gave 252 children aged 2-4 a small piece of cookie, then offered them an opportunity to wait for a predetermined delay period before exchanging it for a larger one. In a first experiment, the children had to exchange the initial food item for rewards two, four or eight times larger. Results showed that children aged 3-4 years old sustained longer time lags for larger rewards than for smaller rewards. This effect was not found in 2-year-old subjects. In a second experiment, a reward 40 times larger than the initial piece was offered to determine the maximum waiting time that children could sustain. All age groups increased their performances. Older children were more successful at waiting, but some children as young as 2 years old were able to tolerate delays of up to 16 min. Older children who chose to give up waiting earlier than their known capacity demonstrated anticipation skills which had not been seen in younger children, showing that they had anticipated an increase in the time lag, and that they had considered both time and reward value when making their decision. Despite the age effect, we did not establish any limits for delaying gratification in children. This study may have educational implications for dealing with behavioral misconduct, which is known to be related to impulsivity control in young children.     

Chicken or egg? Untangling the relationship between orthographic processing skill and reading accuracy

There is increasing evidence of a relationship between orthographic processing skill, or the ability to form, store and access word representations, and reading ability. Empirical research to date has not, however, clarified the direction of this relationship. We examined this question in a three-year longitudinal study of children from Grades 1 to 3. We included standard measures of orthographic processing skill, at both the lexical and sublexical level, and word reading accuracy, as well as controls of vocabulary, non-verbal reasoning, and phonological awareness. In all analyses, word reading predicted progress in acquiring orthographic processing skill, regardless of grade level or orthographic processing measure. In contrast, orthographic processing skill did not predict progress in word reading. Our results suggest that, between Grades 1 and 3, children acquire orthographic processing skill through their reading and that this ability, as characterized by the most common tasks used to date, does not play an independent role in supporting reading acquisition.     

The effect of kurtosis on the power of two test statistics in covariance structure analysis

We study the effect of excess kurtosis on the non-centrality parameters of the rescaled and the residual-based test statistics for covariance structure models. The analysis is based on population matrices and parameters, which eliminates the sampling variability inherent in simulation studies. We show that the non-centrality parameters, and consequently the asymptotic power, decrease as kurtosis in the data increases. Examples are provided to compare this decrease for the two test statistics, and to illustrate how substantial it is.     

Contours of time: topographic construals of past, present, and future in the Yupno valley of Papua New Guinea

Time, an everyday yet fundamentally abstract domain, is conceptualized in terms of space throughout the world's cultures. Linguists and psychologists have presented evidence of a widespread pattern in which deictic time-past, present, and future-is construed along the front/back axis, a construal that is linear and ego-based. To investigate the universality of this pattern, we studied the construal of deictic time among the Yupno, an indigenous group from the mountains of Papua New Guinea, whose language makes extensive use of allocentric topographic (uphill/downhill) terms for describing spatial relations. We measured the pointing direction of Yupno speakers' gestures-produced naturally and without prompting-as they explained common expressions related to the past, present, and future. Results show that the Yupno spontaneously construe deictic time spatially in terms of allocentric topography: the past is construed as downhill, the present as co-located with the speaker, and the future as uphill. Moreover, the Yupno construal is not linear, but exhibits a particular geometry that appears to reflect the local terrain. The findings shed light on how, our universal human embodiment notwithstanding, linguistic, cultural, and environmental pressures come to shape abstract concepts.     

Close, and a cigar!--Why size perception relates to performance

In baseball batting, golf putting, and dart throwing, successful players estimate the size of the target object to be bigger than their less successful counterparts. While more and more empirical evidence is accumulated supporting the existence of this intriguing phenomenon, an explanation of the processes underpinning this effect remains to be provided. Here, we re-analysed data from a dart throwing experiment to examine the proposal--recently put forward by Proffitt and Linkenauger (in press)--that the variability in target-related performance may serve as a scaling metric for perceived target size which may explain why actors who perform consistently close to the target perceive the target to be bigger. Our results confirm that less variability in target-related performance in darts relates to perceiving the target as being bigger, thereby providing initial support for Proffitt and Linkenauger's proposal.     

Anxiety and perceptual-motor performance: toward an integrated model of concepts, mechanisms, and processes

Under anxiety, people sometimes perform poorly. This concerns cognitive performance (e.g., taking an important exam) as well as perceptual-motor performance (e.g., picking up a cup from a table). There is still much debate about how anxiety affects perceptual-motor performance. In the current paper we review the experimental literature on anxiety and perceptual-motor performance, thereby focusing on how anxiety affects the perception, selection, and realization of action possibilities. Based on this review we discuss the merits of two opposing theoretical explanations and build on existing frameworks of anxiety and cognitive performance to develop an integrated model that explains the various ways in which anxiety may specifically affect perceptual-motor performance. This model distinguishes between positive and negative effects of anxiety and, moving beyond previous approaches, recognizes three operational levels (i.e., attentional, interpretational, and behavioral) at which anxiety may affect different aspects of goal-directed action. Finally, predictions are formulated and directions for future research suggested.     

Effect of an aerobic training program as complementary therapy in patients with moderate depression

The aim of this study was to assess the effects of an aerobic training program as complementary therapy in patients suffering from moderate depression. 82 female patients weredivided into a group that received traditional pharmacotherapy (Fluoxetine 20 mg) and a group that received pharmacotherapy plus an aerobic training program. This program was carried out for eight consecutive weeks, three days per week, and included gymnastics, dancing, and walking. Depressive symptoms were measured with the Beck Depression Inventory and the ICD-10 Guide for Depression Diagnosis, both administered before and after treatments. The results confirm the effectiveness of the aerobic training program as a complementary therapy to diminish depressive symptoms in patients suffering from moderate depression.     

At face value: Categorization goals modulate vigilance for angry faces

The present research demonstrates that the attention bias to angry faces is modulated by how people categorize these faces. Since facial expressions contain psychologically meaningful information for social categorizations (i.e., gender, personality) but not for non-social categorizations (i.e., eye-color), angry facial expression should especially capture attention during social categorization tasks. Indeed, in three studies, participants were slower to name the gender of angry compared to happy or neutral faces, but not their color (blue or green; Study 1) or eye-color (blue or brown; Study 2). Furthermore, when different eye-colors were linked to a personality trait (introversion, extraversion) versus sensitivity to light frequencies (high, low), angry faces only slowed down categorizations when eye-color was indicative of a social characteristic (Study 3). Thus, vigilance for angry facial expressions is contingent on people's categorization goals, supporting the perspective that even basic attentional processes are moderated by social influences.     

Biased allocation of faces to social categories

Three studies show that social categorization is biased at the level of category allocation. In all studies, participants categorized faces. In Studies 1 and 2, participants overallocated faces with criminal features--a stereotypical negative trait--to the stigmatized Moroccan category, especially if they were prejudiced. On the contrary, the stereotype-irrelevant negative trait stupid did not lead to overallocation to the Moroccan category. In Study 3, using the stigmatized category homosexual, the previously used negative trait criminal--irrelevant to the homosexual stereotype--did not lead to overallocation, but the stereotype-relevant positive trait femininity did. These results demonstrate that normative fit is higher for faces with stereotype-relevant features regardless of valence. Moreover, individual differences in implicit prejudice predicted the extent to which stereotype-relevant traits elicited overallocation: Whereas more negatively prejudiced people showed greater overallocation of faces associated with negative stereotype-relevant traits, they showed less overallocation of faces associated with positive stereotype-relevant traits. These results support our normative fit hypothesis: In general, normative fit is better for faces with stereotypical features. Moreover, normative fit is enhanced for prejudiced individuals when these features are evaluatively congruent. Social categorization thus may be biased in itself.     

Transitional and steady-state choice behavior under an adjusting-delay schedule

Twelve rats made repeated choices on an adjusting-delay schedule between a smaller reinforcer (A) that was delivered immediately after a response and a larger reinforcer (B) that was delivered after a delay which increased or decreased by 20% depending on the subject's choices in successive blocks of trials. In two phases of the experiment (100 sessions and 40 sessions), reinforcer sizes were selected which enabled theoretical parameters expressing the rate of delay discounting and sensitivity to reinforcer size to be estimated from the ratio of the indifference delays obtained in the two phases. Indifference delays, calculated from adjusting delays in the last 10 sessions of each phase, were shorter when the sizes of A and B were 14 and 25 μl of a 0.6 M sucrose solution than when they were 25 and 100 μl of the same solution. The ratio of the indifference delays was significantly smaller than that predicted on the basis of an assumed linear relation between reinforcer size and instantaneous reinforcer value, consistent with a previous proposal that this relation may be hyperbolic in form. Estimates of the rate of delay discounting based on the ratio of the two indifference delays (mean, 0.08 s(-1)) were similar to values obtained previously using different intertemporal choice protocols. Estimates of the size-sensitivity parameter (mean 113 μl) were similar to estimates recently derived from performance on progressive-ratio schedules. In both phases of the experiment, adjusting delays in successive blocks of trials were analyzed using the Fourier transform. The power spectrum obtained from individual rats had a dominant frequency that corresponded to a period of oscillation of the adjusting delay between 30 and 100 trial blocks (mean, 78). Power in the dominant frequency band was highest in the early sessions of the first phase and declined with extended training. It is suggested that this experimental protocol may have utility in neurobehavioral studies of intertemporal choice.