The effects of signal intensity upon conditioned suppression: Effects upon responding during signals and intersignal intervals

Two rat experiments were run to study the effects of a wide range of signal (CS) intensities on the suppression of licking. In Experiment 1, a light CS was varied over five levels, including zero intensity. Conditioned suppression was found to vary directly with CS intensity, but basal lick rates were not different among groups. In Experiment 2, an attempt was made to disturb the basal rate of licking, while a tone CS was varied over four levels, including zero intensity. Here the suppression of the CS rates was found to be directly related and basal rates inversely related to CS intensity. The results as a whole were consistent with the Perkins-Logan hypothesis regarding the effects of CS intensity upon conditioning, but not with the Rescorla-Wagner model of classical conditioning.     

Two-choice,observational learning and reversal in the rat: S-S versus S-R effects

In Experiment 1, male rats were trained to press both bars in a two-choice apparatus and were then given observational training of a go/no-go discrimination in which the observed operation of two inaccessible, dissimilar bars by a hidden experimenter constituted S+ and S?. After discrimination was established, individual rats were permitted access to the two bars. Six of the seven rats consistently pressed the S+ bar on 10 test trials, but failed to reverse bar preference after observational training was reversed. In Experiment 2, nine naive males received the same observational training as in Experiment 1, but without any pretraining to press either bar. All rats pressed the S+ bar on initial test and did so consistently throughout the 10 trials. Six of these rats received reversal training of the go/no-go discrimination after the 10 test trials. As in Experiment 1, all rats failed to press the new S+ bar. However, five of six rats in another group, which received reversal trainingprior to any test trials, did reverse and press the new S+ bar. In Experiment 3, controls for possible confounding effects of overtraining trials were conducted. These manipulations had no effect; the rats tested before reversal still failed to press the S+ bar, and the rats reversed before testing all reversed or pressed the most recent S+ bar. That is, S-R learning predominated over S-S learning if active, though unreinforced, responding to a particular bar intervened. In contrast, however, a cognitive (S-S) interpretation of directed response learning was supported by the results of Experiment 4, in which the rats that learned the go/no-go discrimination without responding (only by auditory and light cues) failed to press the S+ bar consistently.     

Phonemic awareness in Dutch kindergartners: Effects of task, phoneme position, and phoneme class

The aim of the present study was to provide more insight in the relative difficulty of four tasks testing phonemic awareness: (a) blending, (b) isolation, (c) segmentation, and (d) deletion. At the same time the roles of phoneme position and phoneme class were taken into account in a fully balanced way. To this purpose, 141 kindergartners were presented with four phonemic-manipulation tasks consisting of the same 32 CVC items. Children performed better on phoneme blending and phoneme isolation compared to phoneme segmentation and phoneme deletion. However, performance between and within phoneme tasks appeared also to be dependent on phoneme position. Phoneme class exerted effects within the initial and final position of the four different tasks. The effect of plosives and fricatives compared to that of nasals and liquids on performance was particularly striking. Our findings were explained in terms of sonority and degree of co-articulation in pre-vocalic and post-vocalic plosives.     

Relational aggression: Understanding,identifying, and responding in schools

Relational aggression, harm through injury or manipulation of a relationship, has become fashionable, particularly in the popular press. Mental health professionals in schools can better serve students when they understand what is known about relational aggression, how it influences social behavior, and how it is related to children's well‐being. This article discusses the definition, identification, and consequences of relational aggression. Available intervention programs are introduced, and future directions for research, assessment, and intervention are addressed. © 2006 Wiley Periodicals, Inc. Psychol Schs 43: 297–312, 2006.     

Matching and oddity learning in pigeons: Effects of penalty time for incorrect responding

In simultaneous matching-to-sample and oddity-from-sample tasks, briefly delaying the offset of trial stimuli following an incorrect choice response was found to facilitate task acquisition (Experiment 1). Because thispenalty-time procedure also resulted in longer choice-response latencies, it was hypothesized that any procedure that increased response latency would facilitate task acquisition. However, in Experiment 2, no evidence of facilitation was found when a 2-sec pause was imposed prior to the choice response. The results of Experiment 3 suggest that penalty-time facilitation of acquisition was not due to either the added differential outcome on correct versus incorrect trials (i.e., incorrect choice responses do not darken the keys as do correct choice responses) or the aversive effects associated with trial prolongation (i.e., incorrect responses not only result in the absence of reinforcement but also delay the start of the next trial). Instead, results suggest that birds trained with the penalty-time procedure review the trial stimuli following an incorrect choice.     

Continuity and intensity of shock in one-way avoidance learning in the rat

Six groups of rats (n = 16) differed with respect to the continuity of shock (continuous or discontinuous) and the shock intensity (.3, .8, or 1.6 mA) used during 65 one-way avoidance-conditioning trials. In general, a facilitative effect on one-way avoidance learning was obtained for continuous as opposed to discontinuous shock and for strong as opposed to weak shock. For both variables, the results are opposite to those obtained in discriminated shuttlebox-avoidance and barpress avoidance tasks. The data support an interpretation of the effect of continuity of shock which holds that discontinuous shock is, in effect, less intense than continuous shock. This interpretation allows the effects of the continuity-of-shock variable to be incorporated within the effective reinforcement theory of avoidance learning which has been proposed to account for shock-intensity effects in various avoidance tasks.     

Extinction of chained instrumental behaviors: Effects of consumption extinction on procurement responding

Operant behavior is typically organized into sequences of responses that eventually lead to a reinforcer. Response elements can be categorized as those that directly lead to reward consumption (i.e., a consumption response) and those that lead to the opportunity to make the consumption response (i.e., a procurement response). These responses often differ topographically and in terms of the discriminative stimuli that set the occasion for them. We have recently shown that extinction of the procurement response acts to weaken the specific associated consumption response, and that active inhibition of the procurement response is required for this effect. To expand the analysis of the associative structure of chains, in the present experiments we asked the reverse question: whether extinction of consumption behavior results in a decrease in the associated procurement response in a discriminated heterogeneous chain. In Experiment 1, extinction of consumption alone led to an attenuation of the associated procurement response only when rats were allowed to make the consumption response in extinction. Exposure to the consumption stimulus alone was not sufficient to produce weakened procurement responding. In Experiment 2, rats learned two distinct heterogeneous chains, and extinction of one consumption response specifically weakened the procurement response associated with it. The results add to the evidence suggesting that rats learn a highly specific associative structure in behavior chains, emphasizing the role of learning response inhibition in extinction.     

Partial control and learned helplessness in rats: Control over shock intensity prevents interference with subsequent escape

The effect upon subsequent escape acquisition of control over shock intensity in the absence of control over other shock characteristics was examined. Pretreatment involved random shocks of 1.6 and .75 mA at a density of about 10/min. The experimental group could avoid the higher shock intensity if they leverpressed at least once every 15 sec. Yoked and no-shock rats completed the triadic design. Experimental and yoked animals received all scheduled shocks. Triads were later tested for FR 2 shuttlebox escape at either the .75 mA (low) or 1.6 mA (high) intensity. During testing, avoidance rats performed as well as no-shock rats at the low intensity and escaped even more rapidly at the high intensity. Yoked rats showed interference at both intensities, with interference very marked, including many failures to escape, at the low intensity. These findings indicate that control over shock intensity, by itself, is sufficient to prevent learned helplessness and suggest that control over any salient characteristic of shock may be sufficient for immunization.     

Serial learning and transfer in rats: Effects of changes in stimulus-stimulus associations,pattern structure,and serial position information

Four groups of rats (n=6 per group) were trained in a runway on a serial learning task. Groups were treated identically in Phase 1, receiving two daily presentations of a five-element series consisting of decreasing numbers of .045-g food pellets over successive runs, for example, 14-7-3-1-0. All groups learned to anticipate, and run slowly to, the terminal 0-pellet element, behavior that has been attributed to learning of a less-than rule, stimulus-stimulus (S-S) associations, and knowledge of the serial position of items. In Phase 2, subjects were transferred to one of four test series: 20-14-7-3-0,20-7-3-14-0, 20-14-7-3-1-0, or 20-7-14-3-1-0. Anticipation was disrupted on the first two series, which maintained the integrity of serial position information and in the first case the less-than rule, but eliminated the terminal portion of the associative chain. Anticipation was unimpaired by transfer to either of the last two series. These series maintained the integrity of the terminal 3-1-0 portion of the associative chain but presented altered information about serial position, and in the last case also altered the less-than rule. The results, which supported the memory-discrimination model of rat serial learning, are discussed with reference to related transfer experiments in human serial learning.     

一类非线性方程激波位置与边界条件的关系

利用匹配条件讨论一类非线性方程的激波解.在一定条件下,当边界条件作微小变化时,激波位置作相应的偏移,激波解的形式也发生了较大的改变.最终得出了各种方式情形下,对应的激波解与边解条件的关系.     

Immediate shock,passive avoidance,and potentiated startle: Implications for the unconditioned response to shock

Three experiments were performed to study the immediate-shock freezing deficit, a deficit in freezing in rats that results when electric shock is delivered immediately upon exposure to a novel context. This deficit was accompanied by failures to detect evidence of passive avoidance (Experiment 1) or potentiation of the auditory startle response (Experiment 2). The deficit in freezing was attenuated by preexposure to the shocked context (Experiment 3). The results support the view that fear-related behaviors are activated by signals for shock rather than by shock itself. They also suggest that the immediate-shock freezing deficit is due to a failure to process the to-be-conditioned contextual cues (Fanselow, 1986a, 1990).     

Defensive behavior of the rat in a shock-prod situation: Effects of the subject’s location preference

Experiment 1 investigated the proposition that rats cover the source of aversive stimulation with the bedding material available to them and sought to determine whether familiarization with this material would affect burying. The results indicated that rats are no more likely to cover an aversive object than they are not to cover it, although they collect a considerable amount of bedding material in the area surrounding the aversive object. Experiment 2 demonstrated that the rat’s defensive “burying” toward an aversive object is affected by the subject’s predisposition to displace material toward the front side of the apparatus. Some theoretical complexities involved in considering the act of “burying” toward an aversive object as a defensive behavior are discussed.     

School of shock: film,television and anal education

Since their inception, film and television have been accused of having all kinds of magical powers to alter behaviour, coerce malfeasance and encourage debauchery. Decades of media theory later, the powers of persuasion are in fact thought to be much more modest. One area where popular media is considered to be particularly influential is education, with film and television being perceived to have a role in teaching audiences about certain topics, notably sexuality. This paper focuses specifically on the education provided by film and television about anal heterosex. Screen depictions have a function in not just putting such a sex act onto the audience agenda but in guiding viewers' reception. In this paper, the use of pleasure, pain and power frames is examined to explore the specifics of the anal education provided by screen fiction.     

Early School-leaving in Spain: evolution,intensity and determinants

Spain has one of the highest levels of early school leaving and educational failure of the European Union. The purpose of this paper is to analyse the anatomy of early school leaving in Spain and its characteristics. In order to do so, in the first part we discuss the measurement problems related with this concept and the evolution of drop-out rates in Spain. We argue that the published figures of early school leaving slightly underestimate the phenomenon, and discuss the impact of the increase in immigration rates on the level of educational failure and its very unequal distribution in terms of gender. In a second part, using data from the Labour Force Surveys of 2000 and 2007, we explore the factors behind educational failure by means of a logistic regression. The results of this model confirm the explanatory power of social reproduction hypotheses, but also show that there are important aspects of the patterns and recent evolution of early school leaving which cannot be explained by a single theoretical approach.     

Effects of sample duration,retention interval,and passage of time in the test on pigeons’ matching-to-sample performance

Four pigeons served as subjects in an experiment using the go/no-go delayed matching-to-sample paradigm. The go/no-go method was used because it permits the experimenter to track the time course of discriminative performance throughout the test period, unlike the conventional choice matching procedure. It was found that discriminative test performance increased with longer sample durations; performance decreased with longer retention intervals and also as time passed in the test period. The rate of forgetting was virtually the same when either the retention interval was lengthened or time elapsed in the test. These findings support a modified trace theory, which proposes that the sample stimulus trace decays at a constant rate from the point of sample offset, and that the decaying memory trace is repeatedly compared with the prevailing test stimulus as time passes in the test period.     

Effects of restraint on open-field activity,shock avoidance learning,and gastric lesions in the rat

Many rat studies of learned helplessness confound the stress of restraint with inescapable shock. In the present experiment, albino rats were held immobile for 0, 2, 8, 14, or 18 h. Behavioral deficits were observed in an open-field activity maze and in two-way shuttlebox avoidance acquisition. In the activity maze, a sex X restraint interaction was observed for latency to leave the center square, ambulation, and frequency of center square crossing. Males were slower to leave the center square, had fewer ambulations, and crossed the center square less frequently than females. These effects were potentiated by restraint. Males reared significantly less than females, and restrained animals reared significantly less than nonrestrained animals. Restraint also significantly increased the frequency of grooming. On the avoidance tasks, a significant restraint X trial block interaction indicated slower learning for restrained animals. The severity of the decrements increased with restraint duration. The presence of stomach lesions was positively correlated with stress duration and the severity of the behavioral decrement. The results indicate that restraint produces a variety of behavioral changes which may result in interpretive difficulties for helplessness studies that confound restraint and shock.     

Effects of component training and subsequent sequencing of stimuli on shuttlebox avoidance responding of rats

The serial presentation of two different CSs, with each stimulus having an 8-sec duration (S1₈/S2₈), consistently has resulted in most of the shuttlebox avoidance responses being recorded to the S2 component. Experiment 1 attempted to attenuate this serial CS, delayed-response effect by conditioning the separate components of a serial CS prior to ordering them sequentially. Ten component-training trials were administered, with subjects receiving CS-US pairing to S1 only, S2 only, or to both S1 and S2 presented on separate trials. Two CS durations (8 or 16 sec) during this phase also were compared. Subjects were then given 100 avoidance test trials using the standard serial procedure. The 10 best avoidance responders in each group were selected for analysis. Shorter avoidance latencies were obtained only for subjects receiving component conditioning to S1. CS duration was not a factor in establishing the shorter latencies. Component conditioning to S2 resulted in increasing the total avoidances. Experiment 2 increased the number of component-training trials and the generality of the findings by using a different strain of rats and by extending the testing phase of the study so that all subjects could be included in the analysis. Comparable results were obtained. The theoretical implications of these data were discussed.     

Conjunctive schedules of reinforcement IV: Effects on the pattern of responding of changes in requirement at reinforcement

The effects of different schedule requirements at reinforcement on patterns of responding by pigeons were assessed under conjunctive schedules with comparable response-number requirements, Under one conjunctive schedule (conjunctive fixed-interval fixed-ratio schedule), a response was reinforced after a 6-min interval had elapsedand a specific minimum number of responses had been emitted, Under a second conjunctive schedule, a response was reinforced after the 6-min fixed interval and upon completion of a tandem schedule requirement (conjunctive fixed-interval tandem schedule), This schedule retained the same required minimum number of responses as the first conjunctive schedule, but responses were never reinforced according to a fixed-ratio schedule; the tandem schedule was comprised of a fixed-ratio and a small (.1 to 10.0 sec) fixed-interval schedule, Under the conjunctive fixed-interval fixed-ratio schedule, responding was characterized by an initial pause, an abrupt transition to a high response rate, and a second transition to a lower rate that prevailed or slightly increased up to reinforcement, Under the conjunctive fixed-interval tandem schedule, pauses were extended, response rates were lower, and the initial high rate of responding was generally absent, The above effects depended upon the size of the fixed interval of the tandem schedule, The distinct pattern of responding generated by conjunctive fixed-interval fixed-ratio schedules depends upon occasional reinforcement of fixed-ratio responding and not merely on the addition of a minimum number of required responses.     

Potentiation of responding on a VR schedule by a stimulus correlated with reinforcement: Effects of diffuse and localized signals

In Experiment 1, rats were trained to leverpress on a variable ratio (VR) 30 schedule with a 500-msec delay between the reinforced response and food delivery. Subjects that experienced a signal during the delay responded faster than did control subjects that received the stimulus un-correlated with reinforcement. Higher response rates were obtained when the stimulus used to signal reinforcement was auditory rather than visual. Experiments 2 and 3 compared the effects of signaling reinforcement with either a localized or a diffuse light on responding maintained by VR schedules of reinforcement. Elevated response rates were observed with the diffuse stimulus, but the localized stimulus failed to produce such potentiation. Experiment 3 also examined the conditioned reinforcing power of localized and diffuse visual stimuli. These results are discussed with reference to (1) theories of selective association and sign tracking and (2) their implications for current theories of signaling reinforcement.