Delis-Kaplan Executive Function System

The purpose of the current study was to examine the performance of children with and without ADHD in time reproduction tasks involving varying durations and modalities. Twenty children with ADHD and 20 healthy controls completed time reproduction tasks in three modalities (auditory, visual, and a unique combined auditory/visual condition) and six durations (1 second, 4 seconds, 12 seconds, 24 seconds, 48 seconds, and 60 seconds). Consistent with our predictions, we found main effects of group (participants with ADHD were significantly less accurate than those without ADHD), duration (accuracy decreased as temporal duration increased), and modality (responses in the combined condition were more accurate than those in the auditory condition, which in turn were more accurate than those in the visual condition). Furthermore, predicted interactions between group and duration (the discrepancy in performance between the two groups grew as temporal duration increased), and group and modality (the modality effect was of greater for participants with ADHD) were supported. A marginal, nonsignificant interaction between group, modality, and duration was also found. These findings are discussed in relation to current theory on the nature of cognitive deficits evident in individuals with ADHD, and methodological limitations are noted.     

The Relationship between Performance in Near Match-to-Sample Tasks and Fluid Intelligence

Match-to-sample is a timed task in which a subject is presented with a visual stimulus (the probe) and must select a match to that stimulus (the target) from among an array of distractors. These tasks are frequently employed as tests of basic cognitive abilities and demonstrate consistent correlations with measures of intelligence. In the current study, a match-to-sample task was modified to produce near-match conditions (trials for which no exact match existed). Two factors were manipulated: type of discrepancy between the target and probe (additive or subtractive) and degree of discrepancy between target and probe (1 element or 2 elements). It was hypothesized that introducing near-match conditions would change the processing demands of the task, resulting in increased correlations between decision time and fluid intelligence. Degree and type of discrepancy affected decision times: participants required more time for 2 element discrepancies and additive type discrepancies. Contrary to expectations, increased decision time on a task did not correspond to higher correlations with fluid intelligence. For type, correlations were larger when participants needed to mentally subtract elements from the target in order to make it match the probe (mean r_additive = .399; mean r_subtractive = .451). For degree, correlations were larger for trials where the probe and target differed by one element (mean r = .470) than for trials where the probe and target differed by two elements (mean r = .380). These results seem to indicate that the relationship between the complexity of a task and general intelligence is not as straightforward as has been commonly believed.     

Developmental differences in working memory: Where do they come from?

Several models assume that working memory development depends on age-related increases in efficiency and speed of processing. However, age-related increases in the efficiency of the mechanisms that counteract forgetting and restore memory traces may also be important. This hypothesis was tested in three experiments by manipulating both the processing duration within a working memory task and the time available to restore memory traces. Third- and sixth-grade children performed a complex span task in which they maintained series of letters while adding numbers to series of digits. When we equated processing and restoration times between ages, the developmental difference in working memory span was reduced but remained significant. However, this residual difference was eliminated when the time available to reactivate memory traces was tailored to the processing speed of each age group. This indicates that children employ active mechanisms for maintenance and restoration of memory traces that develop with age.     

Representation of objects and events: why do infants look so smart and toddlers look so dumb?

Research has demonstrated that very young infants can discriminate between visual events that are physically impossible versus possible. These findings suggest that infants have knowledge of physical laws concerning solidity and continuity. However, research with 2-year-olds has shown that they cannot solve simple problems involving search for a hidden object, even though these problems require the same knowledge. These apparently inconsistent findings raise questions about the interpretation of both data sets. This discrepancy may be resolved by examining differences in task demands.     

Morning Passages from Home to Work Among Managers in Israel: Intergender Differences

This paper presents a study on morning passages from home to work. The sample consisted of 226 Israeli parents working in managerial positions (136 men and 90 women). Eighty percent of the participants were Israeli-born, and the rest immigrated to Israel at a young age. In the study, I examined gender differences in emphasis on domestic and work activities at 3 main transitional stages in the morning: home transitions (30 min before leaving for work), on the way to work, and at work (the first 30 min after arrival at work). The findings indicate that in the home-transition women focused more on domestic tasks than on work tasks, whereas men showed the opposite tendency. On the way to work, women tended to intensify their involvement in work activities, but remained strongly concerned with domestic activities. Men, however, focused primarily on work tasks during this transition. In the work transition, both men and women were more concerned with work tasks than domestic tasks. Therefore, even though men and women focused on different tasks in the initial transition, by the time they arrived at the workplace, they were immersed to the same extent in work activities. Furthermore, the participants' age, children's ages, and years of marriage correlated negatively with emphasis on domestic tasks during the home transition regardless of gender.     

儿童能力自我知觉的影响因素概述

该文在综合大量实证研究成果的基础上,全面概括并细致分析了影响儿童能力自我知觉发展与表现的三方面主要因素,即1)主体因素,包括能力概念、认知发展水平、需要动机及相关经验等;2)教育环境;3)任务性质。     

Effects of arachidonic acid on the spatial cognition of aged rats

Abstract:  To examine the effects of arachidonic acid (AA) on age-related cognitive deficits, Fischer 344 rats were given an AA-supplemented powder diet for 12 weeks from 18.6 months old as part of the old AA (OA) group. Other age-matched rats were fed a non-AA-supplemented powder diet as part of the old control (OC) group, and young rats were fed lab pellets as part of the young control (YC) group. When the aged rats reached 20.0 months old, all animals were tested for spontaneous activity in an open field, followed by the Morris water maze place and cue tasks. Escape latencies for the place task showed that the YC rats were fastest, and there was no difference between the OA and OC groups. However, the probe test and the first block of the cue task indicated that the OA rats remembered the location of an invisible platform better than the OC rats. Although the amount of hippocampal AA was larger in the OA rats than in the OC rats, the difference was not significant. The results showed that AA administration to aged animals may alleviate age-related deficits in spatial cognition.     

Groups perform better than the best individuals on Letters-to-Numbers problems

Eighty-two four-person cooperative groups and 328 independent individuals solved a random coding of the letters A–J to the numbers 0–9. On each trial the group or individual proposed an equation in letters (e.g., A + D=?), received the answer in letters (e.g., A + D=B), proposed one specific mapping (e.g., A=3), received the answer (e.g., True, A=3), and proposed the full mapping of the 10 letters to the 10 numbers. As predicted, the groups had fewer trials to solution, proposed more complex equations, and identified more letters per equation than each of the best, second-best, third-best, and fourth-best individuals. We interpret the group superiority as due to the highly intellective nature of Letters-to-Numbers problems, which entail demonstrable recognition of correct answers, demonstrable rejection of erroneous answers, and multiple insights into effective collective information processing strategies.     

Control of oscillatory force tasks: Low-frequency oscillations in force and muscle activity

Force variability during steady force tasks is strongly related to low-frequency oscillations (<0.25 Hz) in force. However, it is unknown whether low-frequency oscillations also contribute to the variability of oscillatory force tasks. To address this, twelve healthy young participants (21.08 ± 2.99 years, 6 females) performed a sinusoidal force task at 15% MVC at two different frequencies (0.5 and 1 Hz) with isometric abduction of the index finger. We recorded the force from the index finger and surface EMG from the first dorsal interosseous muscle and quantified the following outcomes: 1) trajectory variability and accuracy; 2) power spectrum of force and EMG bursting below 2 Hz; 3) power spectrum of the interference EMG from 4 to 60 Hz. The trajectory variability and error significantly increased from 0.5 to 1 Hz task (P < 0.01). Increased force oscillations <0.25 Hz contributed to greater trajectory variability and error for both the 0.5 and 1 Hz oscillatory task (R² > 0.33; P < 0.05). The <0.25 Hz oscillations in force were positively associated with greater power in the <0.25 Hz for EMG bursting (R² > 0.52; P < 0.01). The modulation of the interference EMG from 35 to 60 Hz was a good predictor of the <0.25 Hz force oscillations for both the 0.5 Hz task and 1 Hz task (R² > 0.66; P < 0.01). These results provide novel evidence that, similar to steady contractions, low-frequency oscillations of the motor neuron pool appear to be a significant mechanism that controls force during oscillatory force tasks.     

The enactment effect is due to more than guesses and beliefs

Three experiments examined whether the enactment effect - that is, higher recall of enacted than of corresponding non-enacted information - might be explained by guessing rates and performance expectancies. Experiment 1 checked whether the guessing rate of target items would be higher as a result of a narrowed sampling space defined by the enactment condition. By means of pre-experimental instructions, the subjects in Experiments 2 and 3 were induced to expect respectively a positive enactment effect, a negative enactment effect, or no difference in amount of recall of enacted and non-enacted materials. Experiment 2 had a within-subject design, Experiment 3 a between-subject design. The experiments failed to support the proposed explanations.