The Effect of Selective Serotonin Releasing Agents in the Chronic Mild Stress Model of Depression in Rats

Chronic exposure to mild unpredictable stress has been found to depress the consumption of, and preference for, highly palatable sucrose solution in rats. Stress-induced behavioral deficits may be maintained for a long time, however chronic administration of clinically effective antidepressants can restore normal behavior. This is the first report showing that Sprague-Dawley rats can be used in this model. A preference deficit in this strain of rats took at least 7 weeks to develop; about twice the time required when hooded Lister or Wistar rats are used in this model. Water consumption was not effected by chronic exposure to the mild stress regime and/or by chronic administration of the selective serotonin (5-HT) releasing agent MMAI (5-methoxy-6-methyl-2-aminoindan). The stress-induced deficit in sucrose intake was completely reversed by chronic treatment with MMAI (5 mg/kg, 2 x day) over 3 weeks in the two-bottle tests. In single-bottle tests, chronic treatment with the selective 5-HT releasers, MMAI (5 mg/kg, 2 x day) or MTA (p-methylthioamphetamine; 5 mg/kg, 2 x day), reversed the deficit in rewarded behavior (anhedonia) measured as a decrease in the consumption of 1% sucrose solution in the chronic mild stress model of depression in rats. With the experimental procedure employed, and at a dose of 10 mg/kg/day of 5-HT releasers, the magnitude and onset of this effect were greater than observed following similar administration of the selective 5-HT reuptake inhibitor (SSRI) sertraline (10 mg/kg/day), used as a standard anti-depressant drug.     

The Motivated Expression of Embarrassment Following a Self-Presentational Predicament

ABSTRACT Two experiments tested hypotheses derived from an interpersonal model of embarrassment. According to this model, people who have suffered a self-presentational predicament are motivated to convey to others that they feel embarrassed as a way of repairing their social image and lowering subjective embarrassment in such situations. In Experiment 1, participants who performed an embarrassing task subsequently expressed greater embarrassment if the researcher did not already know that they were embarrassed than if she was aware of their embarrassment. Experiment 2 showed that embarrassed participants who thought that the researcher did not interpret their blushing as a sign of embarrassment subsequently engaged in alternative self-presentational tactics to improve their damaged social image.     

Individual differences in aggressive responses to attack: Internal-external locus of control and field dependence-independence

Two experiments assessed the effect of individual differences on aggression. In both studies subjects were exposed to opponents in the competitive reaction time task who decreased the intensity of their attack from high to low, remained constantly moderate in their attack, or increased the intensity of their attack from low to high. In the first experiment Internal Locus of Control subjects consistently set high intensity shocks in response to high intensity attack and low shocks in response to mild attack. External subjects showed relatively minor variations in their aggressive responses to varying intensities of attack. In the second experiment field-independent subjects set more intense shocks than field-dependent subjects only in the Decreasing attack condition.     

Levels of arousal in high- and low-frequency gamblers

High-(N = 22) and low-(N = 22) frequency gamblers were subjected to provocation with gambling or neutral stimuli prior to playing a poker machine. All Ss used a minimum of AS$3 of their own money and played a machine currently in use in local clubs with a maximum major payout of AS$100. HR and subjective measures of arousal were taken throughout. Neither provocation condition resulted in changes from baseline arousal in either group. Playing was associated with increases in arousal in both groups, but significantly greater arousal was shown by high-frequency players.     

Audiences' reactions to self-enhancing,self-denigrating,and accurate self-presentations

Subjects in three experiments evaluated hypothetical actors whose claims about either an upcoming or past performance and whose performances were system-atically varied from very positive to very negative. Positive, self-enhancing claims were effective in generating favorable evaluations when either the claim was congruent with the performance or the subjects were unaware of how the actor performed. In general, accurate self-presentations were most favorably evaluated, especially when the claim occurred after the performance. The two exceptions to the preference for accurate self-presenters occurred when (a) the actor modestly underestimated a clearly superior prior performance by claiming to have done “only” well or all right, in which case he/she was evaluated more favorably than an accurate but seemingly boastful actor who claimed to have done extremely well, and (b) the actor self-deprecatingly predicted an inferior performance, in which case he/she was disliked even when accurate. Disclaimers about the importance of the performance (e.t., “I did well, but it's no big deal”) were seen as boastful rather than modest and decreased evaluations. The results mirror many of the tactics used by actor-subjects in past experiments, suggesting that people generally vary their self-presentations in optimal fashion to create the most favorable possible impression on the audience.     

Children's avoidance responses to three probabilities of threatened consequences

Children's avoidance responses were conditioned and then extinguished in a laboratory analog of a social threat situation. Aversive events (story interruptions) were programmed to follow either 100% (group E100) of the signals (threats), 60% (group E60) of the signals, or 20% (group E20) of the signals during acquisition. The subjects could avoid the signal and/or the aversive event by responding with lever presses above criterion level. Results indicated that groups E100 and E60 were generally not different from each other but avoided significantly more interruption and signals and responded at a higher rate than group E20. Groups E100 and E60 both shifted their responding from approximately equivalent probabilities of signal and interruption avoidance to relatively greater avoidance of interruptions during acquisition, and then shifted back to equivalent probabilities of signal and interruption avoidance during extinction. Results were discussed in terms of the function of threats as discriminative stimuli.     

Achieving consistency: A Study of basketball officiating

This study investigates the characteristics of professional basketball referees which can account for their successful or unsuccessful performance on the court. Several role inactment skills such as achievement via independence contribute to the prediction of this performance. The main determinant identified, however, is at the group or organizational level. Superior referees have less interindividual variance than do average or relatively unsuccessful referees. This result is discussed in terms of the role requirements of performance in this case. Interpersonal consistency of judgment is relied on for matters permitting only consensual validity. Extensions of these findings to other role enactments are suggested.     

Aggression as a function of the intensity and pattern of attack

Forty Ss competed with an opponent in a reaction time task to avoid receiving shock. The opponent provided either consistently high intensity attack, increasing, decreasing, or consistently low attack. The S's shock settings for the opponent on each trial and ratings of the opponent after the task served as dependent measures. High intensity attack resulted in high intensity counterattack and negative ratings of the opponent. Low intensity attack resulted in low intensity counterattack and relatively positive ratings for the opponent. Decreasing attack resulted in decreasing counterattack and positive ratings of the opponent. Increasing attack resulted in increasing counterattack and comparatively high aggression ratings of the opponent.