Behavioral heat intake as a function of reward duration in rats

Animals working for heat in a cold environment increase responding when reward duration is reduced, but in many instances the increase in responding is not sufficient to prevent a decrease in the amount of heat obtained. Eight experiments were conducted to investigate the reason why rats’ barpress responses for heat are less efficient at short reward durations. The results show that a ceiling effect is not involved and also that improper response-topography or differences in whole-body heat absorptivity or in response effort cannot explain the phenomenon. Evidence was found for the hypothesis that response rate does not increase sufficiently at short reward durations because many short rewards produce a greater afferent signal than do few long rewards. This inequality seems to be caused by characteristics of the stimuli that result in a greater relative change in skin temperature (ΔT) or in the rate of change of skin temperature (δT/δt) for short-duration rewards.     

Functional differentiation of adjunctive drinking and wheel running in rats

Food-deprived rats were exposed to a schedule in which a brief stimulus was presented approximately once every 60 sec. The first leverpress to occur in the presence of the stimulus always turned it off, and produced a food pellet 50% of the time. When the rats were given concurrent access to water, a running wheel, or both, drinking predominated during intervals initiated by pellet delivery, while running predominated during intervals initiated without food. When allowed to obtain all of their food pellets at the beginning of a session, rats drank less and ran more than when the intermittent schedule was in effect, and most drinking occurred within the first half of the session, while running was distributed throughout the session. Adjunctive drinking and wheel running appear to be functionally different, drinking being schedule-induced and food-bound, running being neither.     

A matching law analysis of the reinforcing efficacy of wheel running in rats

Previous research has demonstrated that running in a rotating wheel functions as a reinforcer for leverpressing in rats. In these studies, the pattern of responding was similar to the pattern of responding maintained by consummatory reinforcers, such as food and water. The present study investigated quantitative features of responding maintained by running. In previous experiments in which responses were reinforced according to variable-interval (VI) schedules and food and water served as the reinforcer, the equation for a rectangular hyperbola described the relationship between response rate and reinforcement rate. This experiment tested whether this quantitative regularity also applies to leverpressing maintained by the opportunity to run in a wheel. Fourteen male Wistar rats responded on levers for the opportunity to run. In each session, subjects were exposed to a series of VI schedules. An opportunity to run for 60 sec was the reinforcing consequence. Results showed that response rate was a negatively accelerated function of reinforcement rate, and the relationship between these two variables was described well by the equation for a rectangular hyperbola. To further test the similarity between running and consummatory reinforcers, the response requirement and access were manipulated. In previous experiments with food and water, these types of manipulations differentially changed the two parameters of the hyperbola. A similar pattern of results was obtained with wheel running. Thus, the equation appears to apply to running about as well as it does to consummatory reinforcers.     

The acquisition of a running response as a function of odor buildup,squad rotation,and introduction of naive subjects

A three-phase experiment was conducted in which rats received a double-alternation schedule of reward and nonreward. During Phase 1, the baseline period, double-alternation behavior was displayed earlier and more strongly by subjects run last in the daily sequence. This finding suggests that both reward and nonreward odor cues are cumulative over subjects. During Phase 2, a subject-rotation procedure was initiated; that is, each day the last subject in the previous day’s running sequence was moved to the first position in the sequence, etc. Rotation to the first position in the group led to an immediate disruption of responding. During Phase 3, two naive rats were inserted at the beginning of the running sequence and two at the end. The results, which showed that the naive animals placed at the end of the sequence acquired the patterning response much faster than those placed in the beginning positions, are interpreted as reflecting preparedness to respond to such intensified odors.     

Behavioral contrast as a function of component duration and baseline rate of reinforcement

Three experiments examined changes in size of multiple-schedule behavioral contrast with changes in an independent variable. Experiment 1 found that positive contrast generally increased with increases in component duration when pigeons pressed treadles. Experiments 2 and 3 found that positive and negative contrast generally increased with increases in the baseline rates of reinforcement when pigeons pecked keys. The experiments show that positive and negative contrast vary as similar functions of the same variables. Experiment 1 also suggests that these functions are different for different responses.     

Responding on a multiple variable-time variable-time schedule as a function of component duration

Five pigeons pecked lighted keys for food reinforcers delivered by a multiple variable-time 30-sec variable-time 2-min schedule. The duration of the components varied from 5 sec to 16 min. The rate of responding generated by the more favorable component schedule decreased as component duration increased to an intermediate value and then increased with additional increases in duration. The decrease confirmed a prediction of additive theories of behavioral contrast. The rate of responding generated by the less favorable component did not increase as component duration increased. This decrease may represent a floor effect or it may violate a prediction of one additive theory of contrast.     

机动车方向盘右置右行方案对安全的影响

以驾驶员视野分布理论为基础,通过对交通事故原因的分析,提出了方向盘右置机动车右行的方案。在统计数据的基础上,将新方案与传统的左置右行方案对可能产生的事故结果进行了对比,认为方向盘右置右行方案相对于左置右行方案,可降低机动车与非机动车之间的交通事故,减少伤亡人数。     

Behavioral contrast as a function of component duration for leverpressing using a within-session procedure

Ten rats pressed levers for food reinforcers delivered by multiple schedules. Behavioral contrast was measured using a within-session procedure that presented the baseline and contrast schedules within single sessions. The absolute sizes of both positive and negative contrast increased and then decreased as components lengthened. Negative induction occurred when components were very short. These results question theories that predict that the size of contrast will vary inversely with component duration. They support theories that attribute positive and negative contrast to similar theoretical mechanisms. A comparison of the present results with those of past studies indicates that keypecking by pigeons and leverpressing by rats change as different functions of component duration. Treadlepressing by pigeons and leverpressing by rats change as similar functions. These findings challenge general process theories that argue that all responses obey the same behavioral laws.     

Visual acuity for single lines as a function of hue and age

176 students in grades 2-12 were tested for visual acuity as a function of minimally resolvable red, yellow, green, and blue lines. A 3-way mixed analysis of variance revealed significant differences among the colors, with better acuity for longer wavelengths. Significant age effects as well as a sex X condition interaction were also found. Post hoc analysis revealed a significant quartic trend for age. It is argued that the differential acuity thresholds for hue and the curvilinear age trend may depend upon the coordination of the accommodation and refractive power of the eye, which are affected by differential growth rates of the lens and the axial length of the eye.