共查询到20条相似文献，搜索用时 31 毫秒
1.
Two experiments used a behavior systems approach to relate the form of responses during an interfood clock to the temporal distance of the individual clock stimuli to food. Stimuli proximate to food should better control a focal search mode and related responses, whereas stimuli temporally distant from food should better control a general search mode and related responses. Experiment 1 conditioned two groups of rats with a sequence of four equal-length 12-sec clock stimuli that terminated with food and then tested for the conditioning of a general search mode by presenting an unconditioned moving probe stimulus (either a rolling ball bearing or a rotating mechanical door) during each of the clock stimuli. Consistent with a behavior systems view, contact with the ball bearing was markedly greater during a clock stimulus distant from food. The absence of similar differential contact of the door across the clock stimuli showed that the effect was specific to the ball bearing rather than a general response to stimulus dimensions of movement and sound. Experiment 2 showed that the general search mode was controlled by the clock stimulus rather than the passage of time. 相似文献
2.
We examined how a 50% Pavlovian partial reinforcement (PRF) schedule, versus a 100% continuous reinforcement (CRF) schedule,
altered the asymptotic amount and distribution of focal and general search behavior in rats during 48-sec trials with and
without a four-segment interfood clock (S1-S2-S3-S4-US). Under CRF, but not PRF, average asymptotic focal search (nosing in
the feeder) increased across the last two clock segments (S3 and S4), and more for the clock group than the no-clock group.
Locomotor general search peaked in the second clock segment (S2) for the CRF-clock and CRF-no-clock groups and in S3 for the
PRF-clock groups. Furthermore, the ratio of general search to maximum focal search was higher for the PRF-clock group than
for the CRF-clock group. This pattern of results supports the view that predictable reward presentations temporally organize
search states and related responses between food presentations. The relative expression of these responses varies with the
predictability and proximity of reward and is more sharply defined in the presence of a clock. 相似文献
3.
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. 相似文献
4.
Jennifer J. Higa 《Learning & behavior》1997,25(2):177-184
The present experiment examined temporal control of wait-time responses by interfood interval (IFI) duration. We exposed rats to a sequence of intervals that changed in duration at an unpredictable point within a session. In Phase 1, intervals changed from 15 to 5 sec (step-down) or from 15 to 45 sec (step-up). In Phase 2, we increased the intervals by a factor of four. We observed rapid timing effects during a transition in both phases of the experiment: A step-down and a step-up transition significantly decreased and increased wait time in thenext interval, respectively. Furthermore, adjustment of wait times during step-down was largely complete by the third transition IFI. In contrast, wait times gradually increased across several transition IFIs during step-up. The results reveal dynamic properties of temporal control that depend on the direction in which IFIs change. 相似文献
5.
Pigeons were trained on a variant of the autoshaping procedure in which a keylight stimulus of increasing brightness was used to signal the passing of a 30-sec interfood interval (IFI). Key-pecking developed in all subjects within the first session (65 trials). Within trials, pecking began midway through the IFI, increased throughout the remainder, and decreased just before food delivery. Other behavioral stereotypies were also recorded: Low light levels were associated with a retreat to the rear of the test chamber, and medium light levels (during the midportion of the IFI) were associated with high rates of pacing toward and away from the food source. Probe trials revealed that pecking, pacing, and retreat were all under strong stimulus control; that is, when the light was held constant at its lowest or highest brightness, or when the brightness ramp was presented in reverse order, the behavior pattern almost invariably remained tied to stimulus brightness. Results are discussed in terms of associative and nonassociative sources of the form and sequential characteristics of the behavior. 相似文献
6.
Eight food-deprived Wistar rats developed stable patterns of lever pressing and licking when exposed to a fixed-time 30-s schedule of food pellet presentation. The rats were trained to lever press by presenting the lever 10 s before the programmed food delivery, with the food pellet being delivered immediately upon a lever press. The operant contingency was then removed and the lever was inserted through the entire interfood interval, being withdrawn with food delivery and reinserted 2 s later. On successive phases of the study, a protective contingency postponed food delivery if responses (lever presses or licks) occurred within the last 1, 2, 5, 10, 20, or 25 s of the interfood interval. Lever pressing was reduced at much shorter response–food delays than those that reduced licking. These results demonstrate that reinforcement contributes to the maintenance of different response patterns on periodic schedules, and that different responses are differentially sensitive to delays. 相似文献
7.
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. 相似文献
8.
Five rats were exposed to fixed-time food schedules, ranging from 30 to 480 sec. Three rats displayed a postfood pattern of schedule-induced drinking, with short latencies from food delivery to drinking at all interfood interval durations. In contrast, drinking for the other 2 subjects tended to occur at lower overall levels, and drinking bouts frequently began in the middle of the interfood interval, such that the latency from food delivery to drinking increased dramatically as the interfood interval increased. Observation of these 2 subjects revealed that another form of licking-pawgrooming-occurred reliably after food delivery and before drinking bouts. A between subject comparison of the 3 postfood drinkers and the 2 pawgroomers revealed that, in addition to a common topography (repetitive licking), pawgrooming and drinking were similar with respect to their temporal locus, relation to the interfood interval, and extinction baseline levels. These similarities suggest that drinking and pawgrooming are induced by a common mechanism. Cohen, Looney, Campagnoni, and Lawler’s (1985) two-state model of reinforcer-induced motivation provides a useful framework for the interpretation of these results. 相似文献
9.
Pigeons and rats were exposed to a mixed variable-time extinction schedule of reinforcement. During the variable-time component of the schedule, response-independent food was delivered at either a left or a right feeder. The animals were allowed to perform observing responses to produce either stimuli paired with the component of the mixed schedule that was in effect (temporal information) or stimuli paired with the feeder that might deliver food (spatial information). Only stimuli conveying temporal information reinforced observing. This result contradicts a prediction of the “information hypothesis” of observing, but is consistent with various conditioned-reinforcement interpretations of observing. 相似文献
10.
The expression of cardiac responses to sequences of two sounds was studied in restrained rats following discriminative trace or delay conditioning. Stimuli paired with a tail shock 10 sec later (CS1) elicited conditioned bradycardia. Unpaired or neutral stimuli (CS0) elicited mostly tachycardia. Rats did not learn to suppress responding to nonreinforced sequences with an interval of 6 sec between sounds. Responses to the second stimulus were significantly augmented following a CS1 stimulus, but not following a CS0 stimulus. Real-time summation of simple responses provided a more complete and quantitative prediction of dual responses than did resetting or facilitation. These results extend the time range over which summation may be observed from less than 2 sec to at least 16 sec. They appear to be inconsistent with models involving competition between unitary representations of stimuli in short-term memory and suggest the existence of multiple stimulus traces with independent time courses. 相似文献
11.
When rats learn to anticipate a sequence of stimulus events, such as a serial pattern of different food quantities, they are sensitive to the rule-based formal structure relating the magnitude of successive stimuli. Earlier research has shown that if formal structure is simple (e.g., if a single “less than” rule relates the size of each successive quantity), patterns are learned faster than if formal structure is complex (e.g., if two or more rules such as “less than” and “greater than” relate successive pattern quantities). Two experiments tested the hypothesis that pattern length modulates the role of pattern complexity. We predicted that pattern length and pattern complexity interact in determining pattern difficulty. That is to say, long complex patterns should be learned more slowly than short complex patterns. However, long simple patterns should be learned faster than short simple patterns. In Experiment 1, rats ran a straight runway to receive repeated sequences of food quantities. The long-monotonic group received a formally simple 18-10-6-3-1-0 pattern, in which each number represents a quantity of food pellets. The long-nonmonotonic group received a formally complex 10-1-3-6-18-0 pattern. Similarly, the short-monotonic and short-nonmonotonic groups received 18-1-0 and 1-18-0 patterns. Pattern tracking—fast and slow running in anticipation of large and small quantities of food, respectively—was taken as an index of pattern learning. In Experiment 2, comparable patterns were used, but rats leverpressed in a discrete-trial procedure; response latencies measured pattern tracking. In both experiments, rats learned formally simple patterns faster than they did formally complex patterns. In Experiments 1 and 2, but less clearly in Experiment 2, the predicted interaction was obtained. The results support and generalize the idea that rats encode and use some representation of the formal rule structure of serial patterns as they learn them. 相似文献
12.
Rats were exposed twice in a rotated sequence to a series of six mazes, consisting of hexagonal alleys, balanced for different alley length and structural complexity. Locomotor activity increased with alley length and decreased with structural complexity of the mazes. Locomotion became less stereotyped with increased experience, showing an increasing number of turns, less constant velocity, loss of the initial preference for outward leading alleys and weakening of the forward tendency at reentry from side alleys into hexagonal alleys. In contrast to these qualitative changes of locomotion, the amount of activity remained almost unchanged throughout the experiment. The results suggest that these increases in locomotion complexity depend upon complex interactions between experience and stimulus content of the mazes. 相似文献
13.
The control exerted by various portions of fixed-time and fixed-interval schedules was assessed with a trace-conditioning
procedure. The intervals were segmented into 10 bins. In all but 1 of those bins, the stimuli were presented in different
random orders on each trial. In 1 bin, the stimulus was the same on each trial. The position of this trace stimulus was varied
across phases. The results indicated that a trace stimulus can come to control behavior and that differential control can
extend to even the second tenth of an interfood interval. The results were interpreted as indicating that traditional explanations
of the rate loss in earlier portions of an interfood interval are inadequate and that models such as Palya’s (1993) bipolar
model or Miller and Schachtman’s (1985) comparator model may provide a principled framework with which to understand within-trial
effects. 相似文献
14.
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. 相似文献
15.
Latent inhibition (LI), the retardation of Pavlovian acquisition after nonreinforced preexposure to the conditioned stimulus, is a popular paradigm for studying basic attentional and memory processes from both behavioral and neurobiological perspectives. It is argued that whether LI emerges depends on the behavioral measure used to index conditioning. An experiment with rats demonstrates that stimulus preexposure retards the development of sign-tracking responses directed at the stimulus, but not the development of goal-tracking responses directed at the site of food delivery. These results are consistent with models that explain LI in terms of a deficit in retrieval. 相似文献
16.
Hoffman, Timberlake, Leffel, and Gont (1999) concluded that the tactic of effective trail following (in the form of arm and wall travel), rather than distance minimizing, central-place search, or random search, best characterized the locomotion of rats on a radial arm maze placed flat on the floor of an arena (a floor RAM). The present experiments analyzed further the stimulus control and function of arm and wall travel. Experiment 1 showed that arm travel was controlled more by the edge of a maze arm than by its surface. Experiment 2 showed that rats with whiskers clipped on one side traveled along arms less and along walls more than did intact rats. Experiment 3 showed that maze arms increased search effectiveness and decreased suppression of locomotion by bright light and a novel environment. The results support the hypothesis that arm and wall travel are based on mechanisms of trail following, which, in natural settings, contribute to food finding and regulation of social relations and fear. 相似文献
17.
The degree of stereotypy in the movement patterns of 3 pigeons during noncontingent and contingent periodic food reinforcement was quantified by analyzing the distribution of turning angles, and by using information and Fourier analyses. The results indicated that (1) movement patterns were less stereotyped during noncontingent than during contingent reinforcement, (2) a reversal to noncontingent reinforcement resulted in a degree of stereotypy comparable to that during the first phase of noncontingent reinforcement, (3) movement patterns were maximally stereotyped immediately after food withdrawal and generally became less stereotyped as reinforcement approached, regardless of whether reinforcement was noncontingent or contingent, and (4) higher frequency movements generally accounted for more variance in the movements during contingent than during noncontingent reinforcement. Greater stereotypy in the movements during contingent reinforcement was likely due to a greater probability that similar movements were reinforced during contingent reinforcement. Momentary changes in the stereotypy of the movements within the interfood interval might reflect changes in the level of arousal. 相似文献
18.
This experiment determined if rats could extrapolate a familiar serial sequence of diminishing food quantities by accurately anticipating a novel quantity added to the end of the sequence. In 13 days of training, rats ran in a straight runway to obtain quantities of food pellets presented in sequential order. A strongly monotonic group received repetitions of a formally simple pattern of 14-7-3-1 pellets of food, while weakly monotonic and nonmonotonic groups received formally more complex 14-5-5-1 and 14-3-7-1 patterns, respectively. In subsequent transfer, a 0-pellet quantity was added to each pattern, thus extending pattern length to five elements. Results of the very first pattern repetition containing the added 0-pellet element indicated that rats in the strongly monotonic condition, but not in the others, anticipated the reduced quantity before actually experiencing it. This result supports a cognitive, rule-learning hypothesis for serial learning by rats. 相似文献
19.
Rats confronted with the onset of a light gradient display a transient increase in locomotion called theactivity response (AR) and a dark preference (Godsil & Fanselow, 2004). These experiments demonstrate that the magnitude of the AR can be blunted
with Pavlovian fear-conditioning procedures via associative and nonassociative fear. Although manifested in decreased locomotion,
the blunted AR effect was not due to increased freezing or immobility behaviors. Instead, rats displayed reduced rearing and
an increase in a class of behaviors calledstationary activity. These results suggest that the lighting differential supplied by the cue influences the topography of defensive behavior
and reduces the expression of freezing. This procedure provides a means by which to examine learned and unlearned defensive
responses to the same stimulus. 相似文献
20.
Bright light may be a danger signal for rats because they are more vulnerable to predators in bright environments. We examined
the fear-evoking properties of bright light with a novel open-field procedure that confronts a rat with the sudden onset or
termination of a bright light gradient. The rats did not freeze but exhibited a transient increase in locomotion to light
onset and termination, which we call theactivity response (AR). This finding suggests that the AR is an exploratory response geared at investigating stimulus change. The rats also
displayed a preference for dark to the lighting differential that was not due to the novelty or slight heating differential
supplied by the lamps. These experiments demonstrate that the sudden onset of bright light engages preencounter defensive
behavior, as described by the predatory imminence model (Fanselow & Lester, 1988). This task is amenable to studying light-evoked
defensive responses. 相似文献