Alcohol and the prior residence effect in male convict cichlids (Cichlasoma nigrofasciatum)

A series of experiments were undertaken to demonstrate the dominance advantage of a territorial resident over an intruder (the prior residence effect) in the adult male Convict Cichlid (Cichlasoma nigrofasciatum) and to evaluate the effects of alcohol (ethanol) on this phenomenon. After successfully demonstrating the prior residence effect, additional experiments were conducted in which the resident or intruder was given one of three different doses of ethanol (0.15%, 0.20%, 0.35%). These doses have previously been shown to reduce or increase intraspecific aggression in this species Over the entire dosage range, drugging the intruder produced no changes in the dominance advantage of the resident. However, drugging the resident at the higher doses (0.20%, 0.35%) resulted in loss of the resident's dominance advantage. These effects were not due to impaired locomotor behavior of the drugged fish, as no abnormal motor behaviors were noted. In general, as reported in previous studies, the resident fish, whether drugged or not, typically attacked first. Also as has been previously shown, the fish that attacked (bit) first typically showed eventual dominance. The present results show that the dominance advantage of the territorial resident is not altered by giving an intruder a hypo- or hyperaggression-producing dose of alcohol. Changes in the dominance advantage occur only as a function of drugging the resident, thereby providing evidence that the behavior of the territorial resident is either directly or indirectly (reaction of the intruder to these changes) responsible for the prior residence effect. The present studies also provide some pharmacological approaches for determining the variables important in a laboratory analog of a naturally occurring instance of intraspecific aggression.     

Some adrenal correlates of aggression in isolated female mice

Forty-six female mice (CFW) were isolated for a period of 23 weeks. The effect of isolation on fighting behavior was tested weekly by introducing a naive brown female mouse into the subject's home cage. Total leucocyte counts were obtained at 8 and 14 weeks of isolation. The appearance of leucopenia was used as an index of elevated adrenocortical activity. After 23 weeks of isolation all animals were sacrificed by decapitation. Plasma was collected for corticosterone assay, and paired adrenals were used to assay catecholamine levels. On the basis of the frequency and/or the absence of fighting, the mice were segregated into fighters (n = 22) and non-fighters (n = 17). Analysis of the data by Pearson's product moment correlation and Student's t-test showed that elevated sympathetic-adrenal activity was positively correlated with aggression and that elevated adrenocortical activity was negatively correlated with aggression.     

Background music as a quasi clock in retrospective duration judgments

The segmentation-change model of time perception proposes that individuals engaged in cognitive tasks during a given interval of time retrospectively estimate duration by recalling events that occurred during the interval and inferring each event's duration. Previous research suggests that individuals can recall the number of songs heard during an interval and infer the length of each song, exactly the conditions that foster estimates of duration based on the segmentation-change model. The results of a laboratory experiment indicated that subjects who solved word-search puzzles for 20 min. estimated the duration of the interval to be longer when 8 short songs (<3 min.) as opposed to 4 long songs (6+ min.) were played in the background, regardless of whether the musical format was Contemporary Dance or New Age. Assuming each song represented a distinct segment in memory, these results are consistent with the segmentation-change model. These results suggest that background music may not always reduce estimates of duration by drawing attention away from the passage of time. Instead, background music may actually expand the subjective length of an interval by creating accessible traces in memory, which are retrospectively used to infer duration.     

Why walkers slip: shine is not a reliable cue for slippery ground

In a series of four studies, we investigated the visual cues that walkers use to predict slippery ground surfaces and tested whether visual information is reliable for specifying low-friction conditions. In Study 1, 91% of participants surveyed responded that they would use shine to identify upcoming slippery ground. Studies 2-4 confirmed participants' reliance on shine to predict slip. Participants viewed ground surfaces varying in gloss, paint color, and viewing distance under indoor and outdoor lighting conditions. Shine and slip ratings and functional walking judgments were related to surface gloss level and to surface coefficient of friction (COF). However, judgments were strongly affected by surface color, viewing distance, and lighting conditions--extraneous factors that do not change the surface COF. Results suggest that, although walkers rely on shine to predict slippery ground, shine is not a reliable visual cue for friction. Poor visual information for friction may underlie the high prevalence of friction-related slips and falls.     

Perceptual restoration in toddlers

Perception by adults is a constant interaction between the top-down effects of prior knowledge and the effects of bottom-up perceptual information. One obvious example of this interaction is the perceptual restoration effect, in which adult listeners have the illusion that a word is complete when a portion of it has been replaced by a masking noise. In four experiments, we demonstrate that toddlers fail to show the illusion of perceptual restoration, even in constrained situations with words they know quite well. Not only do toddlers have less prior knowledge than do adults, but they also appear to place less reliance on the knowledge that they do have, at least in the paradigm tested here. Instead, toddlers appear to be more tied to the perceptual information they receive than are adults.     

Effects of comorbid psychopathy on criminal offending and emotion processing in male offenders with antisocial personality disorder

Antisocial personality disorder (ASPD) and psychopathy are two syndromes with substantial construct validity. To clarify relations between these syndromes, the authors evaluated 3 possibilities: (a) that ASPD with psychopathy and ASPD without psychopathy reflect a common underlying pathophysiology; (b) that ASPD with psychopathy and ASPD without psychopathy identify 2 distinct syndromes, similar in some respects; and (c) that most correlates of ASPD reflect its comorbidity with psychopathy. Participants were 472 incarcerated European American men who met Diagnostic and Statistical Manual (4th ed., American Psychiatric Association, 1994) criteria for ASPD and Psychopathy Checklist criteria for psychopathy, who met the criteria for ASPD but not for psychopathy, or who did not meet diagnostic criteria for either ASPD or psychopathy (controls). Both individuals with ASPD only and those with ASPD and psychopathy were characterized by more criminal activity than were controls. In addition, ASPD with psychopathy was associated with more severe criminal behavior and weaker emotion facilitation than ASPD alone. Group differences in the association between emotion dysfunction and criminal behavior suggest tentatively that ASPD with and ASPD without prominent psychopathic features may be distinct syndromes.