Developmental and sex-related differences in preschoolers' affective decision making

This study investigated developmental and sex-related differences in affective decision making, using a two-deck version of Children's Gambling Task administered to 3- and 4-year-old children. The main findings were that 4-year-old children displayed better decision-making performance than 3-year-olds. This effect was independent of developmental changes in inductive reasoning, language, and working memory. There were also sex differences in decision-making performance, which were apparent only in 3-year-old children and favored girls. Moreover, age predicted awareness of task and the correlation between the latter and decision-making performance was significant, but only in 4-year-old children. This study thus indicates that there is a remarkable developmental leap in affective decision making, whose effects are apparent around the age of 4, which according to our results, also marks the age when the correlation of declarative knowledge and decision-making performance becomes significant.     

Mental ability,P300, and mismatch negativity: Analysis of frequency and duration discrimination

Individual differences in mental ability (MA) were examined with event-related potentials (ERP). In addition to using an auditory frequency discrimination task, a duration discrimination task was used to elicit P300 and mismatch negativity (MMN) components of the ERP. Frequency and duration P300 latencies explained 9% and 10% of variance of MAB performance scores independently of each other and commonly 28% of variance. The finding that duration P300 latency explained variance of MA independent of that explained by frequency P300 latency, suggests that temporal information processing is partly dissociable from processing of frequency information in its prediction of MA. Duration and frequency MMNs were shown to be indices of discrimination ability and predicted 11% of variance of MAB performance scores. The outcome of the present study not only emphasizes the importance of both mental speed and discrimination ability for MA but also points to the significance of duration- and frequency-related ERP measures for the understanding of underlying brain mechanisms.     

Extraversion, sensation seeking and electrodermal response: Probing a paradox

Extraversion and psychoticism are thought to relate inversely to electrodermal response amplitude. Paradoxically, sensation-seeking scales, which correlate positively with extraversion and psychoticism, have shown a positive relation to electrodermal response amplitude. In the present inquiry, inverse relationships were obeserved for extraversion and psychoticism with the electrodermal response to visual stimuli. Sensation seeking was also negatively related to the magnitude of the initial electrodermal response to pictures. A lowered response to words for low sensation seekers was observed that appeared to be influenced by skin conductance level.     

Intelligence and information processing during an auditory discrimination task with backward masking: an event-related potential analysis

The relation between mental ability and auditory discrimination ability was examined by recording event-related potentials from 60 women during an auditory oddball task with backward masking. Across conditions that varied in intensity and in the interval between the target and masking stimuli, the higher ability (HA) group exhibited greater response accuracy, shorter response times, larger P3 amplitude, and shorter P3 latency to target stimuli than the lower ability (LA) group. When instructed to ignore the stimuli, the HA group exhibited shorter mismatch negativity latency to deviant tones than the LA group. The greater speed and accuracy of auditory discrimination for the HA group, observed here with multiple measures, is not a consequence of response strategy, test-taking ability, or attention deployment.     

Personality and the effects of stress on recognition memory

The experiment examined the contribution of anxiety, extraversion, neuroticism, and psychoticism to recognition memory for pictures and words using a signal detection method. Independent groups of subjects performed a recognition memory task under one of four conditions (control, noise, threat, and reward) that was intended to capitalize on dispositions which characterize the personality dimensions. In an ego threat condition involving personal evaluation, introverts displayed a performance decrement relative to noise and reward conditions. Psychoticism was inversely related to performance in the noise and threat conditions and directly related in a reward condition. In general, J. A. Gray's (1981) model of anxiety and impulsiveness accommodates much of the data, but the mechanisms which mediate the influence of personality on memory performance are not clear.     

The chronometry of mental ability: An event-related potential analysis of an auditory oddball discrimination task

The relation between intelligence and speed of auditory discrimination was investigated during an auditory oddball task with backward masking. In target discrimination conditions that varied in the interval between the target and the masking stimuli and in the tonal frequency of the target and masking stimuli, higher ability participants (HA) displayed more accurate discriminations, faster response time, larger P300 amplitude, and shorter P300 and mismatch negativity (MMN) latency than lower ability participants (LA). Task difficulty effects demonstrated with variation in mask type indicate that the mask does not interfere with the detection of the deviant target stimulus, but rather that the target and mask are integrated as a single compound stimulus. The temporal effects suggest that the speed of accessing short-term memory is faster for HA than LA and, on the basis of the MMN latency, the effect is accomplished automatically, without focused attention. Moreover, the pattern of results obtained with these data support the view that the accuracy effects are determined by processing speed rather than discrimination ability. Comparator models that accommodate these effects are discussed.     

Stress, Glucocorticoids, and Damage to the Nervous System: The Current State of Confusion

An extensive literature demonstrates that glucocorticoids (GCs), the adrenal steroids secreted during stress, can have a broad range of deleterious effects in the brain. The actions occur predominately, but not exclusively, in the hippocampus, a structure rich in corticosteroid receptors and particularly sensitive to GCs. The first half of this review considers three types of GC effects: a) GC-induced atrophy, in which a few weeks' exposure to high GC concentrations or to stress causes reversible atrophy of dendritic processes in the hippocampus; b) GC neurotoxicity where, over the course of months, GC exposure kills hippocampal neurons; c) GC neuroendangerment, in which elevated GC concentrations at the time of a neurological insult such as a stroke or seizure impairs the ability of neurons to survive the insult. The second half considers the rather confusing literature as to the possible mechanisms underlying these deleterious GC actions. Five broad themes are discerned: a) that GCs induce a metabolic vulnerability in neurons due to inhibition of glucose uptake; b) that GCs exacerbate various steps in a damaging cascade of glutamate excess, calcium mobilization and oxygen radical generation. In a review a number of years ago, I concluded that these two components accounted for the deleterious GC effects. Specifically, the energetic vulnerability induced by GCs left neurons metabolically compromised, and less able to carry out the costly task of containing glutamate, calcium and oxygen radicals. More recent work has shown this conclusion to be simplistic, and GC actions are shown to probably involve at least three additional components: c) that GCs impair a variety of neuronal defenses against neurologic insults; d) that GCs disrupt the mobilization of neurotrophins; e) that GCs have a variety of electrophysiological effects which can damage neurons. The relevance of each of those mechanisms to GC-induced atrophy, neurotoxicity and neuroendangerment is considered, as are the likely interactions among them.     

Extraversion and the effects of frequency and intensity on the auditory brainstem evoked response

Extraversion was positively correlated with the latency of wave I of the auditory brainstem evoked response (BER) at 75, 80 and 85 dB of intensity. Extraverts also tended to display longer latency for wave V than introverts to high frequency, 80-dB tone bursts and to click stimuli at intensity levels which ranged from 55 to 85 dB (SPL). These results are consistent with reports of greater auditory sensitivity (d') and enhanced amplitude of the late (N₁–P₂) cortical evoked response for introverts. The absence of differences in interpeak latency, or central transmission time. center the effects on wave I which is thought to be generated by the cochlear nerve. The present findings may require the elaboration of the neurophysiological bases of extraversion, which presently focuses on differences in cortico-reticular arousal systems, to accomodate individual differences in axonal or synaptic transmission.