Peripheral control of drinking: gastrointestinal filling as a negative feedback signal, a theoretical and experimental analysis.

The studies described here investigated the hypothesis that the osmotic postingestional satiety signal proposed by McCleary operates through a mechanism related to gut filling rather than by osmotically induced shifts of fluid from osmoreceptors in the brain. A control theory model is presented, which was designed to make quantitatively explicit the hypothesis under question. The results showed that when mannitol, which is not absorbed from the intestine, is added to a highly palatable saccharin-glucose mixture, the amount of fluid consumed decreased in inverse proportion to the mannitol concentration. Mannitol was also shown to block fluid absorption from the intestine at a low concentration (approximately .070 M) and at higher concentrations to lead to a net flux of fluid into the intestinal lumen. It was also shown that mannitol in concentrations that reduced the intake of the palatable solution did not induce thirst when the animals were in water balance. It did induce thirst, however, when the animals were tested in a state of negative water balance. The results of these studies, considered as a whole, support the view that McCleary's osmotic postingestional satiety signal acts as an intestinal distention signal rather than by inducing thirst. The model is found to be reasonably accurate as a first approximation, and suggestions are made for improvements.     

The development of same and different judgments

Junior kindergarten children, third-grade children, and college students were given a simultaneous pattern discrimination task, with simple and complex patterns, under either unlimited or limited (150 msec) viewing time. Under unlimited viewing, RTs to same patterns were faster than to different patterns for younger children and older males. Under limited viewing, same and different RTs were equivalent, but more errors were made in judging different patterns by all age groups. The RTs were longer to complex than to simple patterns, but the increase was differentially less for the youngest Ss, especially on same pairs. Since this age difference was found under both limited and unlimited viewing, it was not attributable to age differences in perceptual scanning strategies. The same-different asymmetry in RT under unlimited viewing and in error rate under limited viewing confirms across a wide age range previous findings with adults using codable stimuli. A two-process model for same and different judgments appears to be required, although young children may have had a response bias for same in Expt II.     

Audience reaction as a determinant of the speaker's self-persuasion

This paper tests effects of audience feedback on speaker attitudes. One hundred and seven male subjects with initial beliefs on both sides of an issue (women's role) were assigned to speak for or against their own position; then an “audience” provided one of three types of feedback (speaker was sincere, speaker was insincere, no feedback) in a 2 × 2 × 3 design. Subjects who received sincere feedback showed greater change in the direction of their speech than did those who received insincere feedback. No feedback treatments resulted in intermediate change. This sincere > no feedback > insincere ordering of means held for both pro- and counterattitudinal speakers and for both pretest attitudes. A main effect for pretest attitude was also obtained. Two additional control groups allow for a separate analysis of the effects of (1) preparing and delivering the speech, and (2) audience reaction to the speech.     

Effects of manipulating incentive visibility during the baiting phase of delayed-response problems

Rhesus monkeys were given 960 delayed response (DR) problems. The incentive was either visible or not visible during the baiting phase of each problem, and a 0-, 5-, 10-, or 20-sec intraproblem delay was imposed. Performance was substantially better when the incentive could be seen during the baiting phase. When the incentive was visible during baiting, at all stages of training performance decreased as a function of increased chance levels after short delays, and the rate of improvement with training was comparable after each of the four intraproblem delays. When the incentive was not visible during the baiting phase, an inverse relationship between performance and delay duration became evident only during the later stages of training. On the initial problems performance was at chance levels, and although improvement with training was evident, the rate of this improvement was inversely related to delay duration. The findings were interpreted in terms of Fletcher's orienting response analysis of DR performance.     

Cardiovascular responses to acetylcholine: Effects of pentobarbital and autonomic blocking agents

The effect of acetylcholine chloride (ACh) on heart rate (HR) and blood pressure (BP) was studied in four dogs, awake and under anesthesia by means of pentobarbital sodium. In the awake dog, ACh caused a triphasic change in HR—a rise, fall and secondary rise. The BP showed an initial gradual fall followed by a secondary precipitous fall coinciding with the fall in HR, and then return to base line. Anesthesia accentuated the precipitous fall in HR due to ACh, and narrowed the pulse pressure during the initial fall in BP due to ACh. The effects of atropine sulphate, propranolol and d-tubacurarine on the above were studied, indicating the roles of the sympathetic and parasympathetic systems in mediating the HR and BP reactions to ACh in the awake state and under pentobarbital sodium anesthesia.     

ROLE PERCEPTIONS IN PERU1

Perception des râles au Pérou. — Le Différentiateur de Rôle (RD) a été utilisé pour étudier comment les Péruviens (N = 161) perçoivent les rôles. Les analyses factorielles font apparaître cinq facteurs de comportement identiques pour chacune des deux formes de l'instrument qui ont été utilisées. Une analyse factorielle (two-mode factor analysis) à 6 types de sujets pour chacune des deux formes, mais il n'y a pas de différences majeures dans les structures de réponses par rapport aux facteurs de comportement. Les échantillons sont supposés provenir de la même population. Les résultats sont cohérents avec l'hypothèse selon laquelle des normes de conduite clairement définies sont liées aux différences dans le statut social des paires de rôles qui reflètent le caractère hiérarchique de la société. l'hypothèse d'une invariance interculturelle de la structure factorielle des normes de conduite est confirmée. Les AA. résument brièvement les différences essentielles qui apparaissent dans la perception des rôles chez les Américains, les Grecs et les Péruviens.