Preference for food and water in rats as a function of delay of reward

In Experiment I, rats which were both hungry and thirsty were given a choice between a food reward and a water reward. The animals preferred food to water when the reward was delivered immediately, but preferred water to food when a 30-sec delay was imposed in the goalbox before the reward was received. Experiment II replicated the results of the first experiment and showed, in addition, that when the delay was imposed in a separate delay chamber devoid of differential goalbox cues, subjects preferred food to water, similar to the immediate group. The results were discussed in terms of an incentive value process and a competing response hypothesis.     

Control of pigeons’ keypecking topography by a schedule of alternating food and water reward

Food- and water-deprived pigeons keypecked for food or water reinforcement on alternate trials. Under one condition, explicit stimuli on the key provided information about the trial outcome; under another condition, only the alternation schedule provided this information. Latency and/or response rate differences between food- and water-rewarded trials emerged during both conditions. Response topography also differed on food- and water-rewarded trials. These differences, as revealed by duration and force measurements of the keypeck and by human ratings of the pecking responses as being water- or food-related, were anticipatory in nature. These results not only extend previous work on reward alternation and reward-specific response topographies, but also have implications for theories of animal memory. In particular, these results are amenable to memory models that assume that an animal “codes” information that later must be recalled.     

Chunking,sorting, and rule-learning from serial patterns of brain-stimulation reward by rats

Three studies tested the notion that rats would treat brain-stimulation reward (BSR) as a stimulus alphabet from which rules could be abstracted to learn serial patterns. In Experiment 1, rats learned to track a serial pattern of 18-10-6-3-1-0 pulses of BSR, responding fast in anticipation of large quantities of BSR and slowly or not at all in anticipation of small quantities of BSR. In Experiment 2, rats learned to track a formally simple 18-6-1-0 pattern faster than a formally complex 18-1-6-0 pattern in a within-subjects procedure, indicating that rats can learn to discriminate between simple and complex pattern structures. Finally, in Experiment 3 rats learned either a formally simple 25-18-10-3-1-0 or a formally complex 25-3-10-18-1-0 pattern whose successive elements were separated by an embedded three-element 6-6-0 subpattern. Rats learned to “chunk together” the dispersed pattern elements, and rats receiving the simple pattern learned to track their pattern, whereas rats receiving the complex pattern did not. The latter results suggest that when simple pattern structure is available, rats can simultaneously track rule structures in at least two memory locations. The results of these experiments, using a new testing procedure and, presumably, a new stimulus alphabet, generalize and extend the idea that rats can abstract relational rules to learn serial patterns.     

Effects of sequences of sucrose reward magnitudes with short ITIs in rats

Two experiments assessed the role of aftereffect learning in rats rewarded with sucrose solutions. In Experiment 1, rats were trained in a single straight runway for two trials on each of 18 days, each trial terminating with either large (20% scurose) or small (3% sucrose) reward. The ITI was 3–5 min. The sequence of daily rewards for each of four groups was small-small (SS), small-large, (SL), large-small (LS), or large-large (LL). Response patterning and a simultaneous negative contrast effect were observed in LS and SL relative to the consistently rewarded controls. During 10 massed extinction trials, resistance to extinction was greatest for Group SL, followed in order by Groups SS, LL, and LS. Experiment 2 examined single alternation of large and small rewards administered for 10 trials on each of 31 days with an ITI of 60 sec. Reward for one group was 20% or 3% sucrose while another received 1 or 10 45-mg Noyes pellets. Appropriate patterning developed only in the food-pellet rewarded animals. The overall results suggest that sucrose rewards may produce high-amplitude and long-duration aftereffects which interfere with learning in designs employing several massed daily trials, but which may facilitate learning—relative to food-pellet rewards—with longer intertrial intervals and fewer daily trials.     

Social transmission of food preferences among norway rats by marking of food sites and by gustatory contact

Three experiments were conducted to investigate the social learning and transmission of food preferences by excretory marking among adult male Norway rats. The experiments extend our earlier findings that rats prefer to eat from a food bowl marked by the excretory deposits of conspecifics and that this mechanism can result in the communication and social learning of food preferences (Laland & Plotkin, 1991). Here we investigate whether a tradition of food and food site preferences can become established by these means. Experiment 1 established that the residual cues deposited by rats lose their powers of communication as “markers” of food sites over a 72-h period. Experiment 2 showed that while a socially enhanced preference for one flavored diet could be transmitted from one animal to the next along a chain, it was unstable for an alternative diet. This suggests that social transmission may be more stable when it reinforces a prior preference than when it conflicts with one. In Experiment 3, the stability of socially transmitted food preferences was bolstered by the addition of a second process for the communication of diet preferences-namely, gustatory cues on the demonstrator’s breath. This finding suggests that when a socially transmitted trait is mediated by more than one process, the processes may interact, and the diffusion is likely to be more stable.     

Effects of varied and partial reward on discrete-trial patterning of rats

Rats were trained in the discrete-trial operant apparatus with single alternation of large reward and small reward or large reward and nonreward. followed by either transfer or extinction. The results showed that both groups acquired appropriate response patterning, that patterning is conditioned, and that the stimuli which control patterning are derived from reward conditions on immediately preceding trials. A modification of the sequential hypothesis of instrumental learning was proposed to account for the results.     

Aversive conditioning of naturally produced reward and nonreward odors in rats

Past experiments have reported that rats encountering reward (R) or nonreward (N) goal events emit odors that can be utilized as discriminative stimuli for instrumental behavior by conspecifics. In the present study, thirsty male rats were aversively conditioned by ingestional toxicosis to R and N odors, and their suppression of water consumption in the presence of these odors was measured. Thirsty trained donors were placed into chambers containing R or N goal events to generate, respectively, the R or N odors. Test animals were given eight differential conditioning trials (four with one odor as CS+; four with the other as CS?), involving placement into an odorcontaining chamber with water available, followed by a LiCl injection on CS+ trials. Animals tested in their CS+ odor consumed significantly less water than did CS? and control subjects. Both R and N odors were conditioned by aversive means and readily discriminable from each other. This represents the first laboratory demonstration of aversive conditioning of such naturally produced odors, and it suggests that aversive conditioning may be useful in the study of odorous emissions generally. Implications for innate meanings of R and N odors are discussed.     

Approach and escape to conspecific odors of reward and nonreward in rats

A three-compartment box was used, and a reward odor, or nonreward (extinction) odor, produced by another rat, was present in the middle compartment. Two control odor procedures were also used. The results showed that rats will approach a location in which another rat has previously been given reward more rapidly than they will escape from that location, but showed the opposite effect when the odor was produced by a rat undergoing extinction. The mere presence of an odor associated with another rat had the effect of producing much slower locomotion as compared to a no-odor control condition.     

冯玉祥的奖赏

冯玉祥在泰山隐居时,一日,到泰安城理发,店里的当家大师傅看见大将军前来,连忙敬烟献茶,亲自为他修剪,理得格外仔细。理完发,冯玉祥问需要付多少钱,大师傅满脸堆笑:"将军难得光临敞店,这就算我为您效的犬马之劳。"说完,在一旁献媚地笑起来。明眼人都看得出来,     

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.     

Navigating the Measurement and Monitoring Maze

Assessment of students with disabilities is a critical component of special education. In addition to the complexity of assessment (e.g., high-stakes assessments, progress monitoring, diagnosis), the issue is complicated further by the use of acronyms. This can make both explaining and understanding important information related to students very difficult. Acronyms related to assessment create a virtual alphabet soup that can be confusing for parents, teachers, and school personnel. Assessment acronyms include terms related to both state testing and progress monitoring such as AYP, AA-AAS, AA-MAS, AA-GLAS, RTI, CBA, and CBM. Educators must understand not only the nature and purpose of the various assessments, but they must also be familiar with the assessment acronyms in order to select appropriate assessments to measure the academic progress and performance of students, and to communicate effectively with families and related school professionals. The purpose of this article is to describe common assessments administered in the field of education today as well as to demystify the use of the acronyms related to these assessments and implications for teachers and other educators. Additionally, we point to some resources that can be of value to individuals wishing to establish or expand their repertoires of assessment practices as the current emphasis on progress monitoring continues to unfold.     

Acquisition of barpressing in rats following experience with response-independent food

In a three-group experiment, one group of rats (response-contingent) learned to contact a food cup for Noyes food pellets delivered according to a fixed-ratio schedule of reinforcement. Subjects in another group received a response-independent pellet each time its yoked counterpart earned one. A third (control) group received the same amount of food as the other two groups each day, but the pellets were delivered in mass. Following this training, the rats were placed in a novel experimental chamber in which all responses on a bar were reinforced with the presentation of food pellets. The results showed the response-independent animals to be slower in acquiring the barpress response than the naive control subjects, and the response-contingent subjects to be the fastest.     

Simultaneous and successive contrast with delay of reward

In Experiment I, rats showed no evidence of a successive negative contrast effect (NCE) when shifted from immediate reward to a 15-sec delay of reward. Experiment II provided a direct comparison of NCE in both successive and simultaneous paradigms. As in Experiment I, there was no evidence of a successive NCE, but a reliable simultaneous NCE was observed. These results add support for the view that simultaneous and successive NCEs are not due to a single, common process.     

Effects of reward amount and reward omission on short-term retention

A series of four experiments studied the retention of the response made on a just-preceding trial as a function of the presence, and amount, of food reward given on that trial. Rats were trained to alternate arm choices in a T-maze, and then were tested for alternation with 5- or 30-sec delays between runs. When the subjects had received prior experience with the reward amounts used in testing, larger rewards led to better retention than did small or no rewards. However, when reward omission first occurred during the test phase, it produced more alternation on the following trial than did reward presence. The results suggest that both reward amount and surprisingness determine short-term retention of responses paired with the rewards.     

Generality of US preexposure effects: Transfer from food to shock or shock to food with and without the same response requirements

A series of four experiments, employing mice, investigated the generality of the learned helplessness phenomenon. The first two experiments used preexposure to aversive stimuli (shock), while the other two used preexposure to appetitive stimuli (food). In all of the studies, subjects were preexposed to contingent, noncontingent, or no stimuli (except for Experiment 2) in a Skinner box. During the test, animals preexposed to shock were tested with food, and those preexposed to food were tested with shock. The test was conducted in a similar situation, a Skinner box (Experiments 1, 3), or a different situation—a runway (Experiments 2, 4). Performance decrements were evident when subjects that were preexposed to a noncontingent stimulus were compared with subjects preexposed to contingent stimuli. The differences between the contingent and the noncontingent groups were significant, as were the differences between the contingent and the nonpreexposed groups (except for Experiment 1). The effects cut across the different types of stimuli, situations, and response requirements of the preexposure and test phases.     

复调与《城堡》的解释迷宫

《城堡》的研究现状表明,这部卡夫卡的巅峰之作,正逐渐的被解释成为多义的谜团。人们深入独白体系的泥潭而不能自拔,各种价值标尺都被用来对这部作品进行测量。《城堡》之所以在人们看来,像一个解释的迷宫,是因为人们没有注意到它的根本特性——复调性。文章将对《城堡》的这一特性加以探讨,希望能有助于厘清这个解释的迷宫。     

Acquisition of schedule-induced polydipsia by rats in proximity to upcoming food delivery

Food-deprived rats that receive intermittent delivery of small amounts of food develop excessive drinking--specifically, schedule-induced polydipsia (SIP). A main characteristic of SIP is its occurrence at the beginning of interfood intervals. The purpose of this study was to demonstrate that SIP can be developed toward the end of interfood intervals, in closer proximity to upcoming than to preceding food delivery. In Experiment 1, two groups were exposed to a fixed-time (FT) 30-sec food schedule with water available during the first or the last 15 sec of each interfood interval. Two additional groups, which had access to water throughout, were exposed to FT 30-sec or FT 15-sec schedules of food presentation. The FT 30-sec group with free access to water developed the highest level of intake; similar and intermediate levels were induced in all the remaining groups. In Experiment 2, three groups of rats were exposed to an FT 90-sec food schedule with water available during the first, the second, or the last 30 sec of each interfood interval. One additional group with access to water throughout was exposed to the FT 90-sec schedule of food presentation. The group with free access to water developed a higher level of consumption than did the other groups, but by the end of training none of the four groups showed statistical differences in polydipsic drinking. Results show that adjunctive drinking can be developed in proximity to upcoming food delivery even with long interfood intervals.     

当代美学的价值迷失与价值重建

在社会转型时期所特有的困顿迷茫的社会心理背景下，当代美学也不可避免地陷入了极其尴尬的存在状况中，表现为当下化、商业化和形式化，丧失了其传统的意义和价值．因此，重建美学的价值体系无论对美学本身还是对当代文化发展都至关重要。     

Positive and negative contrast effects obtained following shifts in liquid sucrose reward in thirsty rats

In a repeated shifts experiment four independent groups of thirsty rats received the following treatments: LSLS, LLLS, SSLS, and SSSS, with each letter denoting the magnitude (large or small) of sucrose reward received in each of the four phases of the experiment. While no negative contrast effect (NCE) was obtained in Phase 2, a very reliable positive contrast effect (PCE) was found in Phase 3. Moreover, a significant NCE was obtained in Phase 4. The results were explained in terms of the relative rather than absolute effects of reinforcement.