Metrical categories in infancy and adulthood

Intrinsic perceptual biases for simple duration ratios are thought to constrain the organization of rhythmic patterns in music. We tested that hypothesis by exposing listeners to folk melodies differing in metrical structure (simple or complex duration ratios), then testing them on alterations that preserved or violated the original metrical structure. Simple meters predominate in North American music, but complex meters are common in many other musical cultures. In Experiment 1, North American adults rated structure-violating alterations as less similar to the original version than structure-preserving alterations for simple-meter patterns but not for complex-meter patterns. In Experiment 2, adults of Bulgarian or Macedonian origin provided differential ratings to structure-violating and structure-preserving alterations in complex- as well as simple-meter contexts. In Experiment 3, 6-month-old infants responded differentially to structure-violating and structure-preserving alterations in both metrical contexts. These findings imply that the metrical biases of North American adults reflect enculturation processes rather than processing predispositions for simple meters.     

Protein deprivation in primates: VI. Food preferences of adult rhesus monkeys maintained on low-protein diets.

Three groups of adult female rhesus monkeys, maintained on low-protein diets (.5 gm, 1 gm, and 2 gm protein per kg body weight, were compared with a control group (4 gm protein per kg body weight) on a food-preference task. Food responsiveness was assessed by presenting 8 small pieces of a certain food, equally spaced about the perimeter of a turntable attached to the home cage, and recording number of pieces taken, number of pieces eaten, and elapsed time for taking all 8 pieces. 21 different foods were used in sequence, 3 each from the following 7 categories: cheese, meat, vegetable, nut, cereal, fruit, and candy. Scores on all 3 measures were highly correlated, and the order of preference was generally the same for all groups. The 2 lowest-protein groups accepted more foods at the lower end of the palatability spectrum than did either the 4-gm or the 2-gm group. There was a tendency for the foods least preferred by the protein-deprived monkeys to be themselves high in protein. Thus, although protein deprivation appears to increase the catholicity of food preference, there is no corresponding increase in the relationship between palatability and protein content.     

Behavioral and pharmacological modulation of respiration in rhesus monkeys.

Changes in respiration associated with schedule-controlled behavior were determined in seated rhesus monkeys prepared with a pressure-displacement head plethysmograph for monitoring ventilation continuously during behavioral experiments. Subjects were trained to press a lever under fixed-ratio 40 and fixed-interval 300-s schedules of stimulus termination. Episodic increases in ventilation were closely associated with periods of responding under both schedules. Recurring episodes of increased ventilation occurred during fixed-ratio responding, and were separated by brief 10-s timeouts during which ventilation decreased. Under the fixed-interval schedule, both ventilation and response rate typically increased as the 300-s interval elapsed. The effects of cocaine, caffeine, and two adenosine agonists, 5'-N-ethylcarboxamidadenosine (NECA) and 2-(carboxyethylphenylamino)adenosine-5'-carboxamide (CGS 21680), on behavior and respiration were determined using a cumulative-dosing procedure. Drug-induced suppression of behavior eliminated the episodic increases in ventilation during the performance components of both schedules. Schedule-related increases in ventilation were compared to those produced by elevated levels of CO2 in inspired air. Exposure to 4% CO2 mixed in air increased ventilation in all subjects, and the combined effects of CO2 exposure and schedule-controlled responding on respiration appeared to be additive. The results suggest that behavioral activities may increase ventilation through increased metabolic demand and increased CO2 production.     

Factors influencing sexual performance in male rhesus monkeys.

A 5-yr retrospective study of the sexual behavior of eight adult male rhesus monkeys showed that sexual vigor declined over the years but testosterone levels in peripheral vein plasma did not. Two prospective experiments were then carried out on these males during the sixth year. (a) The four poorest performers were injected daily for 28 days with testosterone propionate (1 mg/kg of body weight). There was no significant increase in level of performance, and behavior was not correlated with plasma levels of testosterone either before or 24 hr after the last hormone injection. (b) All eight males were exposed to novel nonspecific sensory stimulation during tests of sexual behavior. Eight different adult male rhesus strangers-present in the room but not in the test cage-were used as stimuli, one for each experimental test. Sexual behavior during experimental and control tests did not differ.     

Social competence is reduced in socially deprived rhesus monkeys (Macaca mulatta)

Rhesus monkeys deprived for some period from their mother have often served as a model for the effect of adverse rearing conditions on social competence in humans. Social competence is the capacity to react in a species-specific way to social interactions. The current study assesses whether early deprivation from peers also affects the rates of behavior and social competence in rhesus monkeys. This was studied in groups of rhesus monkeys with different rearing conditions: subadult females that were mother-only reared during their first year of life and subsequently housed with peers were compared with subadult females from five naturalistic social groups. Socially deprived monkeys showed higher rates of submission and stereotypic behaviors than socially reared individuals. In addition, they show socially incompetent behavior, since they react with agonistic behavior to nonthreatening social situations. The results suggest that this socially incompetent behavior is rooted in a general feeling of anxiety toward group companions. The authors hypothesize that anxiety negatively affects social information processing, which results in socially incompetent behavior.     

Social responding to mirrors in rhesus monkeys (Macaca mulatta): effects of temporary mirror removal.

As a result of a long-term, longitudinal project initiated in 1978, a pair of rhesus macaques (Macaca mulatta) housed together in front of a mirror all their lives now exhibit relatively little interest in their reflection. Previous work has shown, however, that simply moving the mirror to a new location produces a short-term reinstatement of social responding to their images. As an extension of these findings, in this study the mirror was left in the same position but turned away from the cage. On turning the mirror back to face the cage 5 days later, both animals reacted as if confronted with another pair of monkeys and directed a burst of social responses at the mirror.     

Music perception and octave generalization in rhesus monkeys

Two rhesus monkeys were tested for octave generalization in 8 experiments by transposing 6- and 7-note musical passages by an octave and requiring same or different judgments. The monkeys showed no octave generalization to random-synthetic melodies, atonal melodies, or individual notes. They did show complete octave generalization to childhood songs (e.g., "Happy Birthday") and tonal melodies (from a tonality algorithm). Octave generalization was equally strong for 2-octave transpositions but not for 0.5- or 1.5-octave transpositions of childhood songs. These results combine to show that tonal melodies form musical gestalts for monkeys, as they do for humans, and retain their identity when transposed with whole octaves so that chroma (key) is preserved. This conclusion implicates similar transduction, storage, processing, and relational memory of musical passages in monkeys and humans and has implications for nature-nurture origins of music perception.     

Aggressive behavior during the breeding season of adult female rhesus monkeys (Macaca mulatta)

The aggressive behavior of eight adult female rhesus living in a captive social group was studied prior to and during a breeding season extended by vasectomizing all the adult males in the group. Female reproductive status was ascertained by: recording all adult female-adult male copulations; detecting menstruation by vaginal swabbing; and analyzing serum progesterone levels by radioimmunoassay. Females showed more non-contact aggression during the breeding season, but wounding did not increase. Individual cycling females directed more frequent aggression to: particular adult males subordinate to them, subordinate females also in estrus, and (in a few cases) juveniles and infants.     

Behavior controlled by scheduled injections of cocaine in squirrel and rhesus monkeys.

Rates and patterns of key-press responding maintained under schedules in which responding resulted in intravenous injections of cocaine were studied in squirrel monkeys and rhesus monkeys. Each injection was followed by a 60- or 100-sec timeout period. Schedule-controlled behavior was obtained at appropriate cocaine doses in each species. Under FR 10 or FR 30 schedules, performance was characterized by high rates of responding (usually more than one response per second) in each ratio. Under FI 5-min schedules, performance was characterized by an initial pause, followed by acceleration of responding to a final rate that was maintained until the end of the interval. Under multiple fixed-ratio fixed-interval schedules, rates and patterns of responding appropriate to each schedule component were maintained. Responding seldom occurred during timeout periods under any schedule studied. At doses of cocaine above or below those that maintained characteristic schedule-controlled behavior, rates of responding were relatively low and patterns of responding were irregular. Characteristic fixed-interval responding was maintained over a wider range of cocaine doses than characteristic fixed-ratio responding. Complex patterns of responding controlled by discriminative stimuli under fixed-ratio or fixed-interval schedules can be maintained by cocaine injections in squirrel monkeys and rhesus monkeys.