Adjunctive behavior of the rat under periodic food delivery in a 24-hour environment

The behavior of 4 rats living in complex environments was monitored 24 h per day during free-feeding baseline and under conditions of periodic access to food. Under the periodic schedules, the minimum interfood interval (IFI) was increased from 16 to 512 sec in an ascending series. Periodic food produced robust overall increases in investigation of the feeder, drinking, general activity, and rearing, but not in wheel-running. The temporal distribution of behavior within the IFI was similar across subjects and supported the hypothesis that some responses were largely time-locked to the period immediately following eating, while other responses expanded to fill the interval. However, these response differences were not adequately captured by present classification schemes. Finally, the distribution of drinking following a food pellet strongly resembled the distribution of drinking following bouts of feeding in baseline. The results suggest that adjunctive behavior stems from three sources: (1) a simple increase in the number of opportunities for expression of normal preprandial and postprandial behavior, (2) an increase in the preprandial behavior directed toward the site of expected food, and (3) an increase in the postprandial distribution of both site-directed and more general exploratory behavior. These findings suggest that adjunctive behavior is not extraneous, but is an orderly distribution of responses ordinarily related to feeding and foraging for food.     

不同饵料饲养胭脂鱼幼苗的试验分析

本试验在水泥池集约养殖环境下,采用不同饵料投喂模式分别喂养胭脂鱼幼苗,对其生长情况和养殖成本进行对比试验.结果表明,在水蚯蚓配合饲料投喂的模式中,饲料添加比例在50%～60%时鱼苗的体长和体重增长率最大;综合培育成本考虑,胭脂鱼苗的育苗过程应该考虑以混合饵料投喂模式为主,同时保持50～60%饲料添加比例较为理想.     

Locomotor activity and exploration: The use of traditional manipulators to dissociate these two behaviors in the rat

An apparatus designed by Berlyne was used to dissociate locomotor activity and inspective exploratory responses with the aid of traditional manipulators. In this apparatus, novel and complex stimulation increased exploration but did not affect locomotor activity (LA), d-amphetamine (1.5 mg/kg) increased LA but decreased exploration. These findings provide a double dissociation of the behavioral components. In addition, low intrasubject correlations for the two behaviors were demonstrated. Results are discussed with reference to the need for simultaneous separate measures to obtain valid indices of exploratory behavior and LA.     

Aversively motivated changes in meal patterns of rats in a closed economy: The effects of shock density

Rats lived continuously in an operant chamber in which they were able to press a bar to obtain food on a chained FR50:CRF schedule that allowed them control of both the size and frequency of individual meals. Independent groups of animals were scheduled to receive 12, 24, 48, or 96 electric shocks per day, which were given randomly in time and independent of the subjects’ behavior. Rats could avoid shock by remaining in a safe area of the chamber, but they were always at risk while barpressing. The introduction of shock resulted in a number of changes in feeding patterns. In rats exposed to a possible 12 shocks/day, meal size increased whereas meal frequency changed very little. At 24 shocks/day, meal frequency decreased whereas meal size increased such that net intake remained stable relative to a preshock baseline period. As shock density was increased to 48 or 96 shocks/day, total intake was suppressed. At 96 shocks/day, both meal frequency and meal size decreased dramatically. Shock-related changes were also observed in rates of operant responding and in the amount of time the animals engaged in feeding-related behavior. All of the animals were able to achieve a greater than 50% reduction in the total number of shocks received relative to equivalent random samples of their position in the apparatus taken during baseline. These results support the position that the nature of defensive changes in feeding behavior that are seen when an aversive stimulus is introduced: into a simulated foraging situation varies as a function of risk.     

Autoshaping of initial feeding and drinking reactions in newly hatched chicks

Newly hatched chicks were force-fed food and water throughout rearing, and food, water, or sand reinforcers during exposure to an omission-training procedure. The chicks were thus prevented from performing approach and contact responses to the reinforcer at any time in their lives. Nevertheless, the subjects displayed approach and species-specific feeding or drinking reactions directed toward an illuminated key paired with food or water, but not with sand. Illumination of a key either uncorrelated or negatively correlated with food or water did not engender appreciable responding. Feeding and drinking reactions were topographically distinct, determined by the type of reinforcer, but were not elicited by the reinforcer. These findings support a “learned release” view of autoshaping, according to which phylogenetically preorganized behavior patterns are triggered by distal stimuli paired with biologically significant proximal stimulation, and suggest a close relationship between autoshaping and primitive instances of visual object recognition.     

Mouse exploration and choice of nestboxes differing in size

In this study, mice’s preferences for nestboxes of various sizes were investigated by using, in social conditions, a progressive elimination procedure. Male and female groups (Experiment 1) preferred the medium-small nestbox (15 cm in diameter) as a nest site, followed by the next smaller or next larger one; the largest boxes were chosen last. The order of initial exploration gave different results, with the mice ranking the nestboxes in this case by decreasing order of size. No systematic gender- or group-size-related effects were observed. Six groups of 2 male mice and four groups of 3 male mice (Experiment 2) were subjected to two elimination tests among nestboxes that differed in either both their inner and outer dimensions (matched condition) or their inner dimensions alone (mismatched condition). Except for the smallest nestbox, which was rejected by the mice, the order of preference for nestboxes was linear, in the direction of increasing size. No difference was observed between matched versus mismatched conditions. By contrast, the initial visits (and the number of visits) took the order of decreasing nestbox size, but only in the matched condition, in which the outer dimensions varied; in the mismatched condition, in which the nestboxes were identical on the outside, the various inner dimensions were not found to have any systematic effect on exploratory activity. These results are discussed in terms of the relevance of the spatial features, depending on the motivation (exploration or nest establishment) underlying behavior at a particular time.     

The influence of context-reinforcer associations on instrumental performance

In each of two experiments, rats were trained to press the lever in a Skinner box, food reinforcement being available on a variable-interval 60-sec schedule (VI 60). There followed an “exposure phase” for which the levers were removed from the boxes, and then a final test with the levers replaced to assess the effects of the intervening treatment on instrumental responding. Experiment 1 showed that simple exposure to the box reduced the vigor of instrumental performance in comparison with a condition in which food was made available during the exposure phase. Animals which received no exposure treatment also showed a relatively high rate of response. Experiment 2 demonstrated that an exposure treatment in which the occurrence of food is signaled by a light stimulus also leads to a decline in instrumental responding. These results are held to support the notion that associations between the context and the reinforcer serve to energize appetitive instrumental behavior.     

Effects of reinforcement-paired stimuli on general activity

Two experiments were performed to explore the mechanisms responsible for the increase in activity that occurs in response to stimuli which have been paired with reinforcement (S^R. The first experiment showed a sharp increase in activity to S^R-paired stimuli under conditions in which subjects were not required to perform any instrumental response to obtain the S^R. This result seemed to rule out reinforcement of instrumental “food getting” behavior as the mechanism responsible for the learned activity increases. A second experiment used an “omission training” procedure to further explore the mechanisms underlying the activity increase. In this experiment, S^R was omitted on those trials on which activity increases were present during the stimulus. In this condition, no increases in activity were observed during the stimulus. There was, however, the characteristic increase in activity in a yoked-control group which received the same number and distribution of stimulus-paired S^Rs. The results of the second experiment open the possibility that increases in activity to S^R -paired stimuli could be due to the adventitious reinforcement of motor behavior rather than the Pavlovian conditioning of a motivational state.     

Behavioral contrast and type of reward: Role of elicited response topography

Groups of pigeons were exposed to multiple variable-interval variable-interval and multiple variable-interval extinction schedules of either food or water reinforcement for keypecking. Discriminative stimuli associated with component schedules were located either on the operant key or on a second “signal” key. When the stimuli were projected on the operant key, positive contrast appeared during discrimination conditions with either food or water as the reinforcer. When the stimuli were projected on the signal key, overall responding to the operant and signal keys showed contrast with food, but negative induction with water as the reinforcer. In the latter condition, the signal for the variable-interval shcedule of water reinforcement elicited a variety of water-related behavior, only some of which was directed at the signal. Thus, the type of reward and location of discriminative stimuli interacted to determine the presence or absence of behavioral contrast effects. In large part, these results support and extend the autoshaping view of contrast.     

Behavioral contrast and responding during multiple food-food,food-water,and water-water schedules

Five pigeons pecked lighted keys for food reinforcers delivered by several multiple variable interval 2-min variable interval 2-min schedules. At different times, the components of the multiple schedule both supplied food reinforcers, both supplied water, or one supplied food and the other supplied water. Rates of responding during the water component of the food-water schedule were lower than the rates during comparable components of the water-water schedules (negative contrast). But, the rates of responding during the food component of the food-water schedule were not greater than the rates of responding during comparable components of the food-food schedules (absence of positive contrast) at two different levels of water deprivation. These results raise questions about several theories of behavioral contrast, and they may restrict the scope of any theory that attributes positive and negative contrast to symmetrical factors.     

Intramaze cues and “odor trails” fail to direct choice behavior on an elevated maze

The relative importance of intramaze cues and extramaze cues in directing choice behavior on a radial arm maze was examined using a discrimination procedure which selectively rewarded rats for following only one set of cues. Rats in the intramaze group obtained food from a food cup on the end of each arm. Rats in the extramaze group obtained food from a food cup on a small platform just beyond the end of each arm. All rats were first shaped to perform correctly with the maze in a constant position. Then the maze was rotated to a new position after every choice. For rats in the intramaze group, the food moved with the arms, making intramaze cues relevant. For rats in the extramaze group, the food remained on the platforms (in the same position in the room), making extramaze cues relevant. Rats in the extramaze group performed almost perfectly during maze rotation, demonstrating that intramaze cues were not necessary to support accurate choice behavior. Rats in the intramaze group never performed better than chance, demonstrating that intramaze cues (from the rats, the reinforcement, and the apparatus) were not adequate to control choice behavior. The results of the present experiment are compared to those of other experiments describing the influence of “odor trails” or other olfactory stimuli on choice behavior in mazes.     

Instrumental responding by rats on free-operant schedules with components that schedule response-dependent reinforcer omission: Implications for optimization theories

In two experiments, we assessed whether rats optimize the number of reinforcers per response. In Experiment 1, one group of rats was trained to leverpress for food reinforcement on a simple variable-interval (VI) 60-sec schedule. For another group, a negative fixed-ratio component was imposed on the VI schedule to produce a conjoint contingency in which reinforcement became available on the VI schedule but was omitted when the ratio criterion was satisfied. In Experiment 2, one group of rats responded on a VI schedule and also received response-independent food. For another group, responding above a certain rate canceled the response-independent food. Despite the negative contingency experienced by the groups in Experiments 1 and 2, responding was maintained at a level at which the number of obtained reinforcers was reduced substantially below the maximum number possible. In addition, in both experiments, the groups that experienced the negative contingency responded at a lower rate than did a yoked control group that experienced the same frequency of reinforcement but lacked the negative component. These results demonstrate that although rats do not optimize their behavior with respect to reinforcement, they are nevertheless sensitive to some aspect of the instrumental contingency in operation.     

Motivational mechanisms and schedule-induced behavioral stereotypy

In two experiments, behavioral stereotypies elicited by scheduled presentations of food and water were compared. In Experiment 1, pigeons were exposed to a fixed-time 30-sec (FT 30-sec) schedule of food or water deliveries with a brightening keylight stimulus signaling time to the unconditioned stimulus (UCS) on each trial. Food and water presentations both produced terminal autoshaped keypecking that was similarly distributed in the trial but differed in response topography and persistence. Locomotor interim behavior was different in the two motivational conditions: With food presentations, it consisted of a “retreat” to the rear of the chamber after UCS termination, followed by “pacing” in the midportion of trials. The water schedule produced very little locomotor activity with no regular distribution in the trial. Experiment 2, using a random-time 30-sec (RT 30-sec) schedule, showed that the differences in interim locomotor behavior persisted in the absence of temporal predictability of the UCS and the keypecking terminal response. The results are taken to support Timberlake’s (1983a) behavior-system theory.     

Molecular thermodynamics for cell biology as taught with boxes

Thermodynamic principles are basic to an understanding of the complex fluxes of energy and information required to keep cells alive. These microscopic machines are nonequilibrium systems at the micron scale that are maintained in pseudo-steady-state conditions by very sophisticated processes. Therefore, several nonstandard concepts need to be taught to rationalize why these very ordered systems proliferate actively all over our planet in seeming contradiction to the second law of thermodynamics. We propose a model consisting of boxes with different shapes that contain small balls that are in constant motion due to a stream of air blowing from below. This is a simple macroscopic system that can be easily visualized by students and that can be understood as mimicking the behavior of a set of molecules exchanging energy. With such boxes, the basic concepts of entropy, enthalpy, and free energy can be taught while reinforcing a molecular understanding of the concepts and stressing the stochastic nature of the thermodynamic laws. In addition, time-related concepts, such as reaction rates and activation energy, can be readily visualized. Moreover, the boxes provide an intuitive way to introduce the role in cellular organization of "information" and Maxwell's demons operating under nonequilibrium conditions.     

Problem solving in the rat: Stay vs. shift solutions on the three-table task

Two experiments were conducted to determine the conditions under which a shift problem vs. a stay problem would be easier for animals tested on Maier’s three-table task. When animals were given a prior exploratory experience and a partial feeding during the feeding experience, the stay problem was easier. With a prior exploratory experience and a complete feeding experience, the shift solution was easier. In the absence of prior exploration, rats cannot solve either the stay or shift problem, regardless of the amount of feeding during the feeding experience.     

Banach火柴问题的进一步推广

将Banach问题中的2盒火柴根数不等的情形推广到任意m盒的情形,进而将两盒火柴的根数为独立同分布的随机变量情形推广到任意m盒的情形,同时得到相应的一些结果。     

Transfer of a taste aversion from food to water under various states of deprivation

The importance of ingestive contexts (feeding and drinking) and deprivation states to rats’ transfer of a taste aversion were examined, In Experiments 1 and 2, rats were trained with novel saccharin-treated foods while either food deprived or food and water deprived, They were then tested with a 1,0% saccharin solution while either water deprived or food and water deprived, Comparable aversions to the solution were displayed regardless of deprivation states, Two further experiments examined transfer to a .1% saccharin solution in conjunction with deprivation state change, When both stimulus properties and deprivation were widely discrepant from training to test, reduced transfer was noted. The results suggest that stimulus similarity was a stronger controlling variable than deprivation state similarity in facilitating the transfer of an aversion from a feeding context to a drinking context, The results were viewed as being consistent with the known parameters affecting generalization gradients.     

The free food (contrafreeloading) phenomenon: A review and analysis

Animals will perform an operant response to obtain food when abundant free food is available. These data have implications for current learning theories, especially in terms of the motivational variables associated with such behavior. The present paper reviews the literature and provides an analysis that suggests that responding for food in the presence of free food is importantly controlled by stimulus change attendant upon response-dependent food presentation. This apparent stimulus-reinforcer effect on behavior is compared to that observed in other areas of animal learning research that include preference between schedules of response-dependent and response-independent reinforcement, preference between schedules of signaled and unsignaled reinforcement, autoshaping and automaintenance, and self-reinforcement in animals.     

Serial conditioning as a function of parametric variations of an interfood clock

Two experiments examined the effects of differences in the parameters of a clocked interfood interval on the obtained distribution of responding to the stimuli in that interval. In the first experiment, a 3×3 factorial design assessed the effects of the number of components and the durations of those components. Food was presented irrespective of behavior following 5, 10, or 20 discrete stimuli across durations of 3, 6, or 12 sec each. Responding began at the approximate midpoint of the interval. More responding occurred in earlier portions of the last half of the interval as the number and the durations of individual stimuli decreased or as the overall interfood interval decreased. The second experiment, also a 3×3 factorial design, manipulated the probability and duration of food presentation following a 60-sec trial containing 10 discrete stimuli. A 2.0-, 3.5-, or 5.0-sec food presentation followed 100%, 25%, or 10% of the trials. Responding again began at the approximate midpoint of the interval. More responding occurred in earlier portions of the last half of the interval only when both food duration and the proportion of reinforced trials increased. Both experiments therefore showed that the onset of responding occurs at the approximate midpoint of clocked interfood intervals in spite of a wide variety of CS and US manipulations.