Drinking in a patchy environment: the effect of the price of water.

Rats in a laboratory foraging paradigm searched for sequential opportunities to drink in two water patches that differed in the bar-press price of each "sip" (20 licks) of water within a bout of drinking (Experiment 1) or the price and size (10, 20, or 40 licks) of each sip (Experiment 2). Total daily water intake was not affected by these variables. The rats responded faster at the patch where water was more costly. However, they accepted fewer opportunities to drink, and thus had fewer drinking bouts, and drinking bouts were smaller at the more costly patch than at the other patch. This resulted in the rats consuming a smaller proportion of their daily water from the more costly patch. The size of the differences in bout frequency and size between the patches appears to be based on the relative cost of water at the patches. The profitability of each patch was calculated in terms of the return (in milliliters) on either effort (bar presses) or time spent there. Although both measures were correlated with the relative total intake, bout size, and acceptance of opportunities at each patch, the time-based profitability was the better predictor of these intake measures. The rats did not minimize bar-press output; however, their choice between the patches and their bout sizes within patches varied in a way that reduced costs compared to what would have been expended drinking randomly. These data accord well with similar findings for choices among patches of food, suggesting that foraging for water and food occurs on the basis of comparable benefit-cost functions: In each case, the amount consumed is related to the time spent consuming.     

Procurement time as a determinant of meal frequency and meal duration.

Foraging involves the expenditure of both time and effort in the acquisition of food; animals typically modify their meal patterns so as to reduce these expenditures or costs. The contribution of time, as compared with effort, to the overall cost perceived by an animal is not known. We investigated the effect of foraging time as a cost independent of effort by measuring the meal patterns of rats living in a laboratory foraging simulation in which they earned all their daily intake. They pressed a bar once to initiate an interval (procurement interval) leading to the presentation of a large cup of food from which they could eat a meal of any size. As the length of the interval increased from 1 s to 46 hr, meal frequency decreased regularly. Meal size increased in a compensatory fashion, and total daily intake was conserved through an interval of 23 hr. The changes in meal frequency occurred because of changes in the rat's latency to bar press after each meal. The functions relating meal frequency and size to the procurement interval were of the same shape as those seen when cost is the completion of a bar-press requirement, which entails the expenditure of both effort and time. When the bar-press requirement was increased to 10, meal frequency was reduced, but time and effort did not appear to simply add together in the rat's perception of cost. These data reveal that time is preceived to be a cost by rats foraging in this laboratory environment. These results suggest that the time parameters of foraging are different from those of consumption.     

Trapped in a tight spot: Scaling effects occur when,according to the action-specific account,they should not,and fail to occur when they should

The action-specific account of perception claims that what we see is perceptually scaled according to our action capacity. However, it has been argued that this account relies on an overly confirmatory research strategy—predicting the presence of, and then finding, an effect (Firestone & Scholl, 2014). A comprehensive approach should also test disconfirmatory predictions, in which no effect is expected. In two experiments, we tested one such prediction based on the action-specific account, namely that scaling effects should occur only when participants intend to act (Witt, Proffitt, & Epstein, 2005). All participants wore asymmetric gloves in which one glove was padded with extra material, so that one hand was wider than the other. Participants visually estimated the width of apertures. The action-specific account predicts that the apertures should be estimated as being narrower for the wider hand, but only when participants intend to act. We found this scaling effect when it should not have occurred (Exp. 1, for participants who did not intend to act), as well as no effect when it should have occurred (Exp. 2, for participants who intended to act but were given a cover story for the visibility and position of their hands). Thus, the cover story used in Experiment 2 eliminated the scaling effect found in Experiment 1. We suggest that the scaling effect observed in Experiment 1 likely resulted from demand characteristics associated with using a salient, unexplained manipulation (e.g., telling people which hand to use to do the task). Our results suggest that the action-specific account lacks predictive power.     

Modal Dispositionalism and the (T) Axiom

Philosophia - Yates has recently argued that modal dispositionalism invalidates the (T) axiom. Both Yates and Allen have advanced responses to the objection: Yates’s response proposes...     

Normative data on a battery of neuropsychological tests in the Han Chinese population

In order to develop normative data of a battery of neuropsychological tests in the mainland Chinese population, we examined the performance of 15 neuropsychological tests in 465 healthy subjects (231 males and 234 females) in a population‐based cohort study. The years of education were ranged between 1 and 23 years, and ages were ranged between 16 and 75 years old. The 15 neuropsychological tests cover five domains of neurocognitive functions including attention and speed of information processing, memory and learning, verbal function, visual constructive abilities, and executive function. We also assessed the effects of gender, age, educational attainment on the performance of these neuropsychological tests. The results showed that, as expected, educational attainment and age are the two main factors affecting performance in these tests. Educational attainment has the strongest predictive effect on all tests, while the majority of tests selected in this study are also affected by age at examination to varying degrees. The presented normative data will be useful for future studies in related clinical research, and be of value in transcultural neuropsychological studies.     

Tests of hypothesis in a repeated measures design from a permutation viewpoint

Repeated measures designs have been widely employed in psychological experimentation, however, such designs have rarely been analyzed by means of permutation procedures. In the present paper certain aspects of hypothesis tests ina particular repeated measures design (one non-repeated factor (A) and one repeated factor (B) withK subjects per level ofA) were investigated by means of permutation rather than sampling processes. The empirical size and power of certain normal theoryF-tests obtained under permutation were compared to their nominal normal theory values. Data sets were established in which various combinations of kurtosis of subject means and intra-subject variance heterogeneity existed in order that their effect upon the agreement of these two models could be ascertained. The results indicated that except in cases of high intra-subject variance heterogeneity, the usualF-tests onB andAB exhibited approximately the same size and power characteristics whether based upon a permutation or normal theory sampling basis.This research prepared under Contract No. 2593 from the Cooperative Research Branch of the U. S. Office of Education.     

Electrical self-stimulation of dentate gyrus granule cells

Male albino rats implanted with a chronic stimulating electrode electrophysiologically guided into the granule cell layer of the dorsal dentate gyrus were tested in a self-stimulation paradigm. It was found that subjects self-administer electrical stimulation to the granule cells at low, steady rates. Consistent with the presence of opioid-like immunoreactivity in the granule cell mossy fiber pathway, intraperitoneal injection of the opiate antagonist naloxone diminishes granule cell self-stimulation in a dose-related fashion. The results suggest that a granule cell opioid synapse participates in expression of reward at this site.     

Minor illness and social behavior of infants and caregivers

Fourteen infants attending day care were observed during the first year of life when well and during acute minor illnesses. Comparisons of behavior during 46 afebrile illnesses and a like number of well observations revealed no differences in infant or caregiver behavior. During 24 febrile illness observations, however, infants moved less, contacted toys less, were in closer proximity to teachers, cried more, and looked at teachers more. During a subset of these febrile illnesses, in which teachers recognized that infants were ill, teachers vocalized, gave toys, looked at, touched, held, and fed infants more than when infants were well. Analysis of teacher behavior during infant crying demonstrated that infant cries played an important role in eliciting social responses from teachers during febrile illness. These results suggest that both caregiver perception of illness state and illness-induced changes in infant behavior contribute to increased sociability by caregivers during acute febrile illness.