Elevation and reduction of plasma tryptophan and their effects on aggression and perceptual sensitivity in normal males

Data from experimental animals suggest that 5-hydroxytryptamine (5HT) may have an inhibitory effect on aggression, while clinical studies have found a correlation between pathological aggression and low brain 5HT. To investigate this relationship further we used amino acid mixtures designed to raise or lower the levels of the 5HT precursor, tryptophan. Normal male subjects were given tryptophan-depleted, balanced, or tryptophan-supplemented ammo acid mixtures and tested for aggression 5 hours later. The balanced amino acid mixture served as a control for the tryptophan depletion and supplementation. Testing for aggression was done using the Buss paradigm in which subjects deliver electric shocks to a (nonexistent) partner in response to stimulus tones. Duration and intensity of shock delivered were the measures of aggression, while responsivity to the stimulus tones was the measure of perceptual sensitivity. Neither tryptophan supplementation nor tryptophan depletion had any effect on these measures of aggression or perceptual sensitivity. We conclude that raising or lowering the synthesis of brain 5HT through alterations in tryptophan availability does not influence aggression in normal males as measured by the Buss task.     

Differential effects of seating arrangements on disruptive behavior of fifth grade students during independent seatwork

We investigated teacher versus student seat selection in the context of group and individual seating arrangements. Disruptive behavior during group seating occurred at twice the rate when students chose their seats than when the teacher chose. During individual seating, disruptive behavior occurred more than three times as often when the students chose their seats. The results are discussed in relation to choice and the matching law.     

Psychological Climate,Organizational Commitment and Morale: Implications for Army Captains' Career Intent

The purpose of this research was to examine how work experiences contribute to junior officers' intentions to leave the Army. Specifically, we hypothesized that psychological climate perceptions have direct and indirect effects on intent to leave through affective commitment and morale and that affective and continuance commitment interact to predict intent to leave the Army. The sample for this study was 649 captains who responded to an Army-wide survey, the Fall 2002 Sample Survey of Military Personnel. Results demonstrate support for full mediation, indicating that psychological climate impacts intent to leave the Army by influencing captains' affective commitment and morale. The psychological climate dimension of leadership had the largest impact on affective commitment, morale, and intent to leave the Army. Affective commitment did not interact with continuance commitment to predict intent to leave. Implications for Army retention policies and leadership are discussed.     

Divided attention between simultaneous auditory and visual signals

Past studies of simultaneous attention to pairs of visual stimuli have used the “dual-task” paradigm to show that identification of the direction of a change in luminance, whether incremental or decremental, is “capacity-limited,” while simple detection of these changes is governed by “capacity-free” processes. On the basis of that finding, it has been suggested that the contrast between identification and detection reflects different processes in the sensory periphery, namely the responses of magno- and parvocellular receptors. The present study questions that assertion and investigates the contribution of central processing in resource limitation by applying the dual task to a situation in which one stimulus is auditory and one is visual. The results are much the same as before, with identification demonstrating the tradeoff in performance generally attributed to a limited capacity but detection showing no loss compared with single-task controls. This implies that limitations on resources operate at a central level of processing rather than in the auditory and visual peripheries.     

Subjective Distress to Violations of Trust in Mexican American Close Relationships Conforms to Evolutionary Principles

Sex differences in subjective distress to violations of trust in a close relationship were observed among Mexican American men and women. Imagining a partner’s emotional infidelity and other female-linked violations (for example, a partner who no longer desires to work) distressed a larger percentage of women than men. In contrast, imagining a partner’s sexual infidelity and other male-linked violations (for example, a partner who no longer makes an effort to look physically attractive) distressed a larger percentage of men than women. The results from two studies provided compelling evidence against a social–cognitive explanation of the sex differences and for an evolutionary psychology explanation based on men and women responding to threats to their sex-linked mating strategies.     

Narcissism and body image

This research examined the relationship between narcissism, as measured by the Narcissistic Personality Inventory (NPI; Raskin & Hall, 1979), and body image, as measured by the Body-Self Relations Questionnaire ( Winstead & Cash, 1984), in a nonclinical sample of college students. Also examined were narcissism's relationships to masculinity, femininity, and self-esteem. Results indicated that more narcissistic individuals had more favorable body images and were higher in masculinity and self-esteem. No gender differences were observed in either the levels of narcissism or its body image correlates. Overall, the findings suggest that the NPI measures “adjusted” narcissism rather than the “maladaptive” narcissism emphasized in theoretical and clinical accounts of the construct.     

Cuing mechanisms in autitory signal detection

Detection of auditory signals under frequency uncertainty can be improved by presenting cues to the listeners. Since various cues have been found to differ in effectiveness, three conceivable mechanisms were considered which might account for these differences. Cuing might reduce the number and/or width of the employed auditory filters or listening bands. Also, cues could modulate the precision of frequency tuning of the filters. Psychometric functions were collected in a detection experiment with frequency uncertainty employing three kinds of cues: pure tones whose frequency was identical to that of the signal (iconic cues), complex tones with a missing fundamental equal to the signal (complex cues), and pure tones with a certain frequency relation to the signal (relative cues). Compared with a no-cue condition, all cue types improved detection performance. Fitting models to the data suggests that in the no-cue condition as well as the complex-cue condition, multiple bands were utilized, and that the iconic and relative cues induced single-band listening. There is no indication that accuracy of frequency tuning was responsible for cue-efficiency differences.