David A. Stevens

Sex differences in human jealousy: A coordinated study of forced-choice, continuous rating-scale, and physiological responses on the same subjects

Abstract Previous investigators have confirmed the evolutionary hypothesis that the sexes differ in their responses to sexual vs. emotional infidelity and have taken their results as suggesting the existence of a mechanism that regulates the perceptions of threat, the emotional responses, and the physiological reactions that constitute jealousy. This notion implies that these three categories of response should occur systematically in the same group of subjects. However, no study has been done to confirm this implication. This study is the first to demonstrate the traditional findings concerning these three categories of response on the same group of subjects. Overall, the results of this investigation are consistent with the core evolutionary hypothesis of sex differences in human jealousy.

Effects of oral chemical irritation on taste

Oral irritation was induced by rinses with capsicum oleoresin and with piperine, constituents of red and black pepper, respectively. The perceived intensities of two concentrations of each of four tastants representing the four classical taste qualities were evaluated after rinsing with these irritants. Comparing taste intensity after rinses with capsicum and after control rinses with emulsifying agents or water, there were significant decrements in taste intensity of citric acid and quinine, and on one concentration of sucrose, but no effect on salt. The effects of piperine were more broad, with significant decrements in perceived intensity relative to emulsion controls for all substances.

Learning and perception of oddity problems by lemurs and seven species of monkey

Eight nonhuman primate species were compared in three experiments utilizing the oddity paradigm. The sample included 4 lemurs (Lemur catta), 26 Old World Monkeys (Macaca mulatta, M. nemestrina, M. speciosa, andCercopithecus nictitans) and 21 New World Monkeys (Cebus apella, Lagothrix humboldti andSaimiri sciurea). EveryS was first trained 60 days on “outside oddity” problems. Next,Ss solved “outside” oddity problems constituted from two short and two tall cylinders, and were tested for their perception of oddity withDavis andMcDonalds (1962) technique of varying the height of the centerplaced but nonreinforced stimulus. In the final experiment,Ss were given ambiguous oddity problems that could be solved either for form or color cues, andEs recorded preference.Cebus and woolly monkeys formed oddity learning sets as well as or better than any of the Macaque monkeys, but relatively poor performances were made by squirrel monkeys, spotnose monkeys, and lemurs. Woolly monkeys were outstandingly accurate in their perception of oddity based on changing stimulus height, no other species approaching them in this skill. Old World Monkeys were much more likely than New World Monkeys to use color as a cue.

The effects of p-chlorophenylalanine, a depletor of brain serotonin, on behavior: II. Retardation of passive avoidance learning

Abstract Rats were tested for passive avoidance learning following injection of p-chlorophenylalanine in Steroid Suspending Vehicle, or the vehicle only. In Exp. 1, the subjects were trained for 20 trials before testing; in Exp. 2, the subjects were trained to a criterion before testing. In both experiments, subjects given p-ClPhe learned more slowly than controls. This supported the hypothesis that p-ClPhe, a specific depletor of brain serotonin, reduces emotionality rather than increases learning ability.

Putting out the fire: Effects of tastants on oral chemical irritation

Intense oral irritation, lasting 10 min or more, was induced by rinses with I or 2 ppm capsaicin or with 100 ppm piperine. Subjects judged the perceived irritation after these treatments while periodically rinsing their mouths with solutions of one of four tastants (quinine, sucrose, NaC1, or citric acid), with water, or with nothing (a “no-tastant” condition). The decay of perceived irritation over time was linear for piperine and exponential for capsaicin. The decline in irritation was fastest during trials with citric acid and with sucrose (but more so for sucrose in the capsaicin trials), intermediate for NaC1 and water, and slowest for quinine and the no-tastant condition. Perceived irritation was generally lower while tastant solutions were held in the mouth (relative to irritation rated before sipping them or after expectoration), suggesting an inhibitory effect of oral cooling.

The effects of p-chlorophenylalanine, a depletor of brain serotonin, on behavior: I. facilitation of discrimination learning

Abstract Rats were given either position discrimination and discrimination reversal, simultaneous brightness discrimination, or successive brightness discrimination tasks. Half of the subjects were injected with p-chlorophenylalanine (p-CIPhe) in Steroid Suspension Vehicle and half were injected with the vehicle only. Rats given p-CIPhe learned the two brightness discriminations with fewer errors than the control animals. No differences were found between groups given the position discrimination and discrimination reversal task. Since p-CIPhe severely depletes brain serotonin with only a slight reduction of brain catechol amines, it is likely that reduction of brain serotonin was responsible for the facilitation of learning found in previous experiments where both serotonin and catechol amines were reduced.

Responses by humans to oral chemical irritants as a function of locus of stimulation

Different areas of the mouth varied in responsiveness to chemical irritation. Subjects were stimulated with 7-mm filter-paper disks containing capsaicin or piperine, which are irritant components of red and black pepper, in seven different regions of the mouth. They reported intense sensations from stimulation of the tip of the tongue, side of the tongue, and posterior palate, all of which contain gustatory receptors, and less intense sensations from the cheek and anterior palate. Capsaicin produced relatively more intense responses from the lip and posterior tongue than did piperine. Sensations produced by stimulation of these small areas grew over time. The patterns of qualitative adjectives used to describe the sensations arising from the two compounds were not the same. These results suggest that irritative chemical stimuli may be qualitatively differentiable.

Open-Field Responses of Rats to Odors from Stressed and Nonstressed Predecessors

Male rats were observed on a clean table with extending runways. Paired comparisons were made with clean runways, those on which conspecifics had been stressed, and previously present but not stressed. The subjects stopped more frequently and for a longer duration on runways with predecessors than on clean ones. Stopping was more frequent on runways with stressed predecessors than with nonstressed predecessors. When runways from stressed predecessors were present, there was more frequent urination on the table than when those runways were not used, despite that in the former conditions the subjects spent considerably less time on the table than on the runways.

Age-related changes in flavor perception.

Three groups of subjects, aged 18–25 years (Young), 36–45 years (Middle) and 56–65 years (Old) judged the similarity of pairs of pureed fruits and vegetables and rated the purees on 10 attribute scales. Multidimensional scaling of the similarity judgments produced four-dimensional solutions for each age group. Dimensions associated with tactile and texture attributes were found for each group. An hedonic dimension was indicated for Young and Middle groups, but sweetness ratings correlated with that dimension only for the Young group. Intensity was an important dimension for the Old group only. In general, the Young rated all the foods as having a more bitter flavor and sharper character than did the older ones. As a control, subjects also rated the similarities of foods by names only. Analysis of this scaling showed no age differences.

Fright reactions in rats to conspecific tissue.

Abstract Rats were trained to traverse a runway for water reinforcement. Then separate groups were tested with rat or guinea pig muscle homogenate, blood, or brain homogenate applied to the runway. Rat muscle and blood evoked significantly higher frequencies of fright reactions (elimination, freezing, or retreating) and significantly lower frequencies of orienting/sampling responses than evoked by guinea pig muscle and blood, or rat brain. This supports the interpretation that conspecific muscle and blood contain an alarm substance ( Schreckstoff ) and eliminates other possible interpretations of these reactions to conspecific blood and muscle.