Auditory List Memory in Rhesus Monkeys

Auditory memory of 2 rhesus monkeys was tested in a serial probe recognition task. Lists of four environmental or natural sounds were followed by a retention interval and a test. The test matched one of the list items on half of the trials. The retention interval was varied across sessions. Six experiments showed similar results and changes in the serial position function. At short retention intervals, there was good memory for first list items (primacy effect) and poor memory for last list items. At intermediate retention intervals, memory improved for last list items (recency effect). At long retention intervals (20 s and 30 s), the recency effect was strong, and the primacy effect had dissipated. These auditory primacy and recency effects and their changes with retention interval were opposite to those for visual memory. Implications for processes and mechanisms of memory are discussed.     

Self-Corrected Reaching in a Three-Location Delayed-Response Search Task

Infants watched an experimenter hide a toy in one of three wells and then attempted to retrieve it after a brief delay. Seven-month-olds performed at chance. Nine-month-olds reached correctly on 43% of trials, which is significantly better than chance. After an incorrect reach, infants were allowed to choose between the two remaining locations. Seven-month-olds responded at a chance level on their second reach, but 9-month-olds chose correctly more often than would be expected by chance despite a 10- to 20-s delay between hiding and search. One cause of error on the initial reach was a profound bias toward the center well. In Experiment 2, the wells were covered simultaneously, and the infant's spatial orientation was disrupted during the delay; this procedure eliminated the centripetal bias. Nine-month-olds still responded correctly more often than would be expected by chance on their second reach. These findings suggest that 9-month-olds sometimes have a more durable working memory for location than is generally reported for that age group.     

Blocking Effects in Two-Choice Discrimination Tasks in Rhesus Monkeys Macaca Mulatta

The Psychological Record - The present experiments investigated blocking effects in rhesus monkeys (Macaca mulatta) in a discrimination learning paradigm using a single stimulus modality. Two...     

Risk Factors for Infant Abuse and Neglect in Group-Living Rhesus Monkeys

This study investigated maternal abuse and neglect of offspring in a large population of rhesus monkeys over a period of 29 years. Abuse and neglect did not occur together and were associated with different risk factors. Infant abuse was concentrated in 8 of 57 families and among closely related females. Abuse was also repeated with successive offspring. In contrast, infant neglect was not affected by genealogical factors, was not repeated with successive offspring, and was displayed mostly by primiparous mothers. These results suggest that abuse and neglect may be different phenomena and that infant abuse in group-living monkeys could represent a good animal model for investigating the mechanisms underlying the intergenerational transmission of child maltreatment.     

Continuity and Change in Emotional Reactivity in Rhesus Monkeys Throughout the Prepubertal Period

We examined continuity and change in emotional reactiviy as assessed by hypothalamic–pituitary–adrenal (HPA) activity in rhesus monkeys. Plasma samples were obtained from mother-peer–reared and surrogate-peer–reared monkeys and assayed for cortisol concentrations at 5 time points in infancy. Both plasma and saliva samples were collected for cortisol assay from the same monkeys as 1-, 2-, and 3-year-old juveniles, respectively. Plasma cortisol concentrations increased during the first 5 months of life and decreased from 1 to 3 years of age. Females consistently had higher plasma cortisol concentrations than males. Plasma cortisol concentrations were lower in surrogate-peer–reared than mother-peer–reared monkeys during the first month of life. Juvenile plasma cortisol concentrations were significantly correlated with infant cortisol levels at all but the earliest time point. Analysis of salivary cortisol from a subset of animals showed a similar age-related decline and the presence of a significant rearing effect, with lower concentrations in surrogate-peer–reared juveniles, but no sex difference. Salivary and plasma cortisol concentrations in these animals were significantly correlated.     

Cue enhancement as a function of task set

The hypothesis was tested that the intention to use a particular cue relation would enhance the effectiveness of that particular cue in determining the resulting perception. For this purpose, a situation was presented in which the apparent depth position of an object in a configuration of objects would differ depending upon which of two possible cue relations (size cues) were used. The results support the conclusion that the perceived depth position of the object differed in the expected directions as a function of the task set. The data of the study are discussed with respect to the “adjacency principle” which states that cue efficiency is determined by the relative adjacency of objects between which the cues occur. Although the effect of cue set upon the perception seems to be small compared with that of adjacency, it cannot completely be ignored.     

Interposition as a Cue for the Perception of Relative Distance

Monitoring sleep through electroencephalography and electroculography has identified the different sleep stages in which nightmares, night terrors, and sleepwalking occur. Questionnaire surveys have supplemented the findings of case studies of these sleep disorders. Neurotransmitters operative during these sleep disorders have enlarged the knowledge of the psychophysiological dimensions especially of nightmares.     

Probabilistic Phonotactics as a Cue for Recognizing Spoken Cantonese Words in Speech

Previous experimental psycholinguistic studies suggested that the probabilistic phonotactics information might likely to hint the locations of word boundaries in continuous speech and hence posed an interesting solution to the empirical question on how we recognize/segment individual spoken word in speech. We investigated this issue by using Cantonese language as a testing case in the present study. A word-spotting task was used in which listeners were instructed to spot any Cantonese word from a series of nonsense sound sequences. We found that it was easier for the native Cantonese listeners to spot the target word in the nonsense sound sequences with high transitional probability phoneme combinations than those with low transitional probability phoneme combinations. These results concluded that native Cantonese listeners did make use of the transitional probability information to recognize the spoken word in speech.     

Grade Expectations as a Function of Sex, Academic Discipline, and Sex of Instructor

Twelve hundred and fifty college students starting introductory courses in thirteen academic disciplines were asked to predict their grade in the course. Results showed that overall, males predicted higher grades for themselves than did females (p <.001). This held true for entering freshmen as well as for those with previous college experience. The phenomena was noted in 26 of 37 classes tested, including 7 of 9 in the natural sciences, 11 of 13 in the social sciences, but only 8 of 15 in the humanities. Sex of the instructor was irrelevant, raising the question of whether female instructors as role models have the positive effect upon women students that has been claimed. The differences found were slight, but persistent. Both sexes predicted very high grades. The data suggest that sex differences in prediction were not based on a female sense of incompetence, but upon a greater willingness among males to make highly positive predictions.     

Monkeys perform as well as apes and humans in a size discrimination task

Whether the cognitive competences of monkeys and apes are rather similar or whether the larger-brained apes outperform monkeys in cognitive experiments is a highly debated topic. Direct comparative analyses are therefore essential to examine similarities and differences among species. We here compared six primate species, including humans, chimpanzees, bonobos, gorillas (great apes), olive baboons, and long-tailed macaques (Old World monkeys) in a task on fine-grained size discrimination. Except for gorillas, subjects of all taxa (i.e. humans, apes, and monkeys) were able to discriminate three-dimensional cubes with a volume difference of only 10 % (i.e. cubes of 50 and 48 mm side length) and performed only slightly worse when the cubes were presented successively. The minimal size discriminated declined further with increasing time delay between presentations of the cubes, highlighting the difficulty to memorize exact size differences. The results suggest that differences in brain size, as a proxy for general cognitive abilities, did not account for variation in performance, but that differential socio-ecological pressures may better explain species differences. Our study highlights the fact that differences in cognitive abilities do not always map neatly onto phylogenetic relationships and that in a number of cognitive experiments monkeys do not fare significantly worse than apes, casting doubt on the assumption that larger brains per se confer an advantage in such kinds of tests.     

Distribution of Practice as a Factor Affecting Learning And/Or Performance

Earlier studies considering distribution of practice as a factor affecting learning and/or performance have employed a transfer design and consequently have failed to provide the means for refuting the contention that postrest performance was the manifestation of extended practice, a temporary performance variation, or some form of the “Hawthorne effect” rather than the result of the independent variable. The present experiment provided adequate control, and results indicated that distribution of practice was a factor affecting performance rather than learning.     

Transformed Facial Similarity as a Political Cue: A Preliminary Investigation

Experimental subjects evaluated a political candidate whose face was digitally altered to absorb the subjects' facial structure. For half of the subjects, the photograph of the candidate was morphed such that the image presented was a blend composed of 60% of the unfamiliar Caucasian male and 40% of the subject. For the other half the photograph was unaltered. Given previous research on implicit familiarity (Zajonc, 1968, 1980), we predicted that the morph would advantage the candidate. The results demonstrated no main effect of the similarity manipulation. However, there was a robust similarity by gender interaction. Male subjects evaluated the morphed candidate more favorably than the unaltered photograph, while female subjects rated him more negatively. We discuss potential explanations for this interaction effect and explore the possible implications of facial similarity as a political cue in both high- and low-information elections.     

The Factor of Sex in Testimonial Accuracy

Abstract

The study assessed the effects of character, professional status, and intentions of a criminal on the magnitude of suggested punishment in a hypothetical experimental setting. The sample was composed of 120 male Indian undergraduates. The analysis yielded a significant main effect of intentions as well as interaction effects of Intentions × Character and of Intentions × Character × Status Factor. The results lend support to cognitive dissonance and attribution theories.     

Pavlovian Conditioning to a Diazepam Cue with Yohimbine as the Unconditional Stimulus

On multiple occasions, rats were administered diazepam (2.0 mg/kg, ip) followed 30 min thereafter by yohimbine hydrochloride (2.5 or 5.0 mg/kg) or isotonic saline (forward conditioning groups). Three additional groups (backward conditioning controls) were given equivalent injections, but in reverse order. After eight such pairings, the effects of a single injection of diazepam on motor performance (balancing on a rotating drum) was assessed. Rats that had received either dose of yohimbine during forward conditioning trials maintained their balance longer than the saline controls. After four additional conditioning trials, the animals’ activity patterns in a plus-maze screening test for anxiolytics were examined. Placed into the maze after a single test injection of isotonic saline, the behavior of all groups was virtually identical: less than 16% of total entries into or time spent in the four arms of the maze was spent in the two “open” arms (unprotected by surrounding walls). When tested in the maze again, but 35 min after a single injection of diazepam, the groups that had received diazepam but not yohimbine during the conditioning phase exhibited the expected increase in open-arm activity, and equivalent increases were found in backward conditioning groups. However, the group previously conditioned with 2.5 mg/kg of yohimbine following diazepam also showed an increased open-arm activity when tested with diazepam alone, but it was significantly greater than that seen in the control group. In contrast, the group conditioned with 5.0 mg/kg yohimbine following diazepam exhibited no effect of diazepam upon their plus maze activity; consequently, these animals spent less time in the open arms than either of the other groups. Yohimbine alone normally decreases open-arm activity (a putative “anxiogenic” effect) in a linear dose-dependent fashion. The fact that it had a bidirectional conditional effect on the diazepam cue drug demonstrates that a conditional response in drug → drug conditioning cannot always be predicted on the basis of the behavioral response to the signaled drug. Consideration is given to possible reasons for these effects of diazepam → yohimbine pairings in terms of the known neuropharmacological properties of yohimbine.     

When Possibility Informs Reality: Counterfactual Thinking as a Cue to Causality

People often engage in counterfactual thinking, that is, imagining alternatives to the real world and mentally playing out the consequences. Yet the counterfactuals people tend to imagine are a small subset of those that could possibly be imagined. There is some debate as to the relation between counterfactual thinking and causal beliefs. Some researchers argue that counterfactual thinking is the key to causal judgments; current research suggests, however, that the relation is rather complex. When people think about counterfactuals, they focus on ways to prevent bad or uncommon outcomes; when people think about causes, they focus on things that covary with outcomes. Counterfactual thinking may affect causality judgments by changing beliefs about the probabilities of possible alternatives to what actually happened, thereby changing beliefs as to whether a cause and effect actually covary. The way in which counterfactual thinking affects causal attributions may have practical consequences for mental health and the legal system.     

Sex differences in communication skills as measured by a modified relationship inventory

Previous studies have provided some indication that females are more empathic than males and that individuals show greater empathy when relating to persons of the same sex. Because the research has been equivocal, the present study attempted to replicate these findings for not only empathy but also three other communication skills measured by the Barrett-Lennard Relationship Inventory: congruence, regard, and unconditionality of regard. The subjects for this study were 20 male and 41 female students in an undergraduate experiential course in interpersonal relations. All students were placed in training groups, and the co-trainers for these groups completed ratings on a modified Relationship Inventory for each of their students. Reliability data on this inventory were satisfactory. Female students were given slightly higher ratings on all skills at both the beginning and end of the group experience, but none of the differences were significant. Male co-trainers rated the skills of male students higher than did female co-trainers, but a comparable same-sex effect for female students was not demonstrated. Thus, the experimental hypotheses were partially supported.