A psychophysical measure of attention deficit in children with attention-deficit/hyperactivity disorder

The authors explored the temporal mechanism of attention deficit in children with attention-deficit/hyperactivity disorder (ADHD). In rapid serial visual presentation tasks in which two targets (T-sub-1 and T-sub-2) were presented in close temporal proximity among distractors, participants tried to identify T-sub-1 and detect T-sub-2 in one (dual-task) experiment and only to detect T-sub-2 in a second control (single-task) experiment. The sensitivity of T-sub-2 detection was analyzed using signal detection theory. The attentional blink--the impairment in T-sub-2 detection following the identification of T-sub-1--was increased in magnitude and protracted in the patients. Moreover, some ADHD children appeared to have a blink largely normal in magnitude but temporally displaced toward a later time. The authors hypothesize that a slower closing of the attention gate may mediate this specific attention impairment in ADHD children.     

Hand movements deviate toward distracters in the absence of response competition

In a series of experiments, participants reached to targets in the presence of visual distracters that were either adjacent to the target or located along the reach path. The reaching movements were affected by the presence of the distracters, with the movement paths deviating toward the distracters. Those deviations were observed under two different conditions: (a) one in which the distracter could potentially have been a movement target; and (b) another in which the distracter never was a possible target. Because the movement was affected by the distracter in both situations, the results suggested that response competition is not necessary for distracter-induced reach-path deviations. Instead, the authors propose that attention to a distracter is sufficient to affect the to-target movement. The movement deviations may reveal an effective mechanism for coping with stimulus-rich environments.     

Trial spacing is a determinant of cue interaction

Four conditioned lick suppression experiments with rats examined the effect of trial spacing on cue interaction. Experiments 1 and 2 found overshadowing to be eliminated with massed compound stimulus-outcome pairings and the usual trial spacing effect to be reversed with compound acquisition trials. Experiment 3 found that whether acquisition compound-outcome pairings were massed or spaced determined the effect of posttraining extinction treatment. Extinction of the overshadowing cue reduced responding following massed training and increased responding following spaced training. Extinction of the context decreased responding following massed training. Experiment 4 found the conditioning and devaluation results to be associative and stimulus specific. These results are in accord with the extended comparator hypothesis (J. C. Denniston, H. I. Savastano, & R. R. Miller, 2001).     

Diencephalic damage decreases hippocampal acetylcholine release during spontaneous alternation testing

A rodent model of diencephalic amnesia, pyrithiamine-induced thiamine deficiency (PTD), was used to investigate diencephalic-hippocampal interactions. Acetylcholine (ACh) release, a marker of memory-related activation, was measured in the hippocampus of PTD-treated and control rats prior to, during, and after spontaneous alternation test. During behavioral testing, all animals displayed increases in ACh release. However, both the percent increase of ACh release during spontaneous alternation testing and the alternation scores were higher in control rats relative to PTD-treated rats. Thus, when rats are tested on a task with demands dependent on the hippocampus, it appears that the hippocampus is not fully activated after diencephalic damage.     

Somatosensory processing in the biological relatives of schizophrenia patients: a signal detection analysis of two-point discrimination

This study examined 2-point discrimination performance in 1 st-degree biological relatives (n = 39) of individuals with schizophrenia and normal adult control participants (n = 30) recruited from the community. They completed an objective 2-point discrimination task, adapted for use with a signal detection approach to permit separation of discriminability (i.e., sensitivity, d') from response bias/ criterion (or motivation, lnbeta). Relatives revealed poorer performance on the d' index compared with controls. The 2 groups did not differ on lnbeta, suggesting a genuine difference in sensitivity but not response bias. The sensitivity deficit might reflect decreased spatial acuity and/or impaired intensity cue processing of tactile stimuli. Poor performance on the d' index was most closely associated with 2 schizotypic features, namely "odd beliefs/magical thinking."     

Cultural variations in optimistic and pessimistic bias: do Easterners really expect the worst and Westerners really expect the best when predicting future life events?

The authors compared levels of optimistic and pessimistic bias in the prediction of positive and negative life events between European Americans and Japanese. Study 1 showed that European Americans compared with Japanese were more likely to predict positive events to occur to self than to others. The opposite pattern emerged in the prediction of negative events. Study 2 replicated these cultural differences. Furthermore, positive associations emerged between predictions and occurrence of life events 2 months later for both European Americans and Japanese. Across both studies, results of within-groups analyses indicated that both groups expected negative events to be more likely to occur to others than to self (optimistic bias). In addition, Japanese expected positive events to be more likely to occur to others than to self (pessimistic bias). However, European Americans failed to show the expected optimistic bias for positive events.     

心算加工年老化及其机制研究

以１７２名２０－７９岁成人为被式对心算加工的年老化过程及其机制进行了研究。任务为连续减法心算,依难度分为５种：１０００－１,１０００－３,１０００－１３及１０００－１７。结果表明,年龄与心算难度存在明显的交互作用,且随着年龄增加,不同难度心算效率均以幂函数形式降低。     

心算加工年老化及其机制研究

以172名20－79岁成人为被试对心算加工的年老化过程及其机制进行了研究。任务为连续减法心算,依难度分为5种：1000－1、1000－3、1000－7、1000－13及1000－17。结果表明,年龄与心算难度存在明显的交互作用,且随着年龄增加,不同难度心算效率均以幂函数形式降低。结构方程建模分析发现心算加工年老化过程存在两个中介作用因子,即速度因子和非速度因子,且速度因子对非速度因子存在明显的正效应。