Retardation tests of inhibition following discriminative autoshaping

Four experiments explored various applications of the retardation test of inhibition following discriminative autoshaping. In all studies, discriminative autoshaping consisted of food-reinforced presentations of a green key-light CS+ and nonreinforced presentations of a vertical white line on a green background CS?. In Experiment 1, the inhibitory properties of the vertical Une CS? were assessed by comparing the acquisition of keypecking to the now-reinforced vertical line CS in groups previously receiving discriminative autoshaping (as above), discriminative autoshaping with a red key CS?, and nondiscriminative autoshaping. The results indicated that the former CS? was retarded in being transformed into a CS+. In Experiment 2, the discriminative autoshaping procedure was followed by testing for acquisition with independent groups receiving one of four different CSs differentiated by line orientation. The results indicated that the orientation attribute of the CS? was inhibitory, in that a between-subjects resistance-to-reinforcement gradient of inhibition was obtained. In Experiment 3, discriminative autoshaping was followed by a within-subjects resistance-to-reinforcement generalization test based on line orientation, which failed to yield an orderly gradient. The implementation of a DRO contingency in the within-subjects test (Experiment 4) was ineffective in generating an incremental gradient. Implications for inhibitory assessment methodology are discussed.     

Retardation of conditioned excitation following operational inhibitory blocking

Water-deprived adult rats were used in a conditioned-suppression-of-licking procedure to determine the effect of inhibitory training with a novel stimulus trained in simultaneous compound with a previously established conditioned inhibitor. This procedure constitutes an inhibitory analogue to the excitatory blocking procedure in classical conditioning. The conditioned-inhibition training consisted of either explicitly unpaired CS and US presentations or negative contingency training, in which the likelihood of the US was greater in the absence than in the presence of the CS, but the CS and the US were occasionally paired. To assess conditioned inhibition, a retardation test was used, and comparable retardation was obtained for subjects that were administered the blocking treatment and control subjects given similar conditioned-inhibition training with a compound stimulus in which the nontarget element was not previously established as a conditioned inhibitor.     

Temporal integration and instrumental conditioned reinforcement

Stimuli associated with primary reinforcement for instrumental behavior are widely believed to acquire the capacity to function as conditioned reinforcers via Pavlovian conditioning. Some Pavlovian conditioning studies suggest that animals learn the important temporal relations between stimuli and integrate such temporal information over separate experiences to form a temporal map. The present experiment examined whether Pavlovian conditioning can establish a positive instrumental conditioned reinforcer through such temporal integration. Two groups of rats received either delay or trace appetitive conditioning in which a neutral stimulus predicted response-independent food deliveries (CS1→US). Both groups then experienced one session of backward second-order conditioning of the training CS1 and a novel CS2 (CS1–CS2 pairing). Finally, the ability of CS2 to function as a conditioned reinforcer for a new instrumental response (leverpressing) was assessed. Consistent with the previous demonstrations of temporal integration in fear conditioning, a CS2 previously trained in a trace-conditioning protocol served as a better instrumental conditioned reinforcer after backward second-order conditioning than did a CS2 previously trained in a delay protocol. These results suggest that an instrumental conditioned reinforcer can be established via temporal integration and raise challenges for existing quantitative accounts of instrumental conditioned reinforcement.     

Extinction of conditioned inhibition: Effects of different outcome continua

For some decades, failures to find extinction of inhibition through unpaired presentations of the inhibitor were taken as evidence against conceptualizing inhibition as the symmetrical counterpart of excitation. Recently, however, our group has demonstrated successful extinction of inhibition in human causal learning. In two experiments, we replicated and strengthened this finding by using an outcome continuum that could take on negative, neutral, or positive values. In contrast, the use of a dichotomous outcome continuum (either neutral or positive) resulted in the well-known nonoccurrence of extinction. Extinction of inhibition through the pairing of inhibitors with neutral outcomes was assessed by (1) comparing the (presumably) extinguished inhibitor with a second inhibitor that had not been presented with a neutral outcome in the extinction stage, and (2) demonstrating the course of extinction in participants’ predictions.     

Extinction and food-reinforced inhibition of conditioned salivation in dogs

The present experiment compared two methods of eliminating a classically conditioned response in dogs, extinction and reinforcement of nonsalivation, using both a within- and between-subjects experimental design. Eighteen dogs were trained for 16 days in Phase I, 16 days in Phase II, and 8 days in Phase III. In Phase I, each subject received classical conditioning training to two stimuli. In Phase II, Group 1 received extinction training to one stimulus and reinforcement of nonsalivation to the other stimulus. Group 2 received continued classical conditioning training to one stimulus and reinforcement on nonsalivation training to the other. Group 3 received continued classical conditioning training to one stimulus and extinction training to the other. In both the within- and between-subjects comparisons, responding to the stimulus associated with extinction was eliminated faster than responding to the stimulus associated with reinforcement of nonsalivation.     

Proactive interference by cues presented without outcomes: Differences in context specificity of latent inhibition and conditioned inhibition

This report is part of a larger project examining associative interference as a function of the nature of the interfering and target associations. Lick suppression experiments with rats assessed the effects of context shifts on proactive outcome interference by latent inhibition (LI) and Pavlovian conditioned inhibition (CI) treatments on subsequently trained Pavlovian conditioned excitation treatment. LI and CI were trained in Context A during Phase 1, and then excitation treatment was administered in Context B during Phase 2, followed by tests for conditioned excitation in Contexts A, B, or C. Experiment 1 preliminarily established our LI and CI treatments and resulted in equally retarded acquisition of behavioral control when the target cue was subsequently trained as a conditioned excitor and tested in Context A. However, only CI treatment caused the target to pass a summation test for inhibition. Centrally, Experiment 2 consisted of LI and CI treatments in Context A followed by excitatory training in Context B. Testing found low excitatory control by both LI and CI cues in Context A relative to strong excitatory control in Context B, but CI treatment transferred to Context C more strongly than LI treatment. Experiment 3 determined that LI treatment failed to transfer to Context C even when the number of LI trials was greatly increased. Thus, first-learned LI appears to be relatively context specific, whereas first-learned CI generalizes to a neutral context. These observations add to existing evidence that LI and CI treatments result in different types of learning that diverge sharply in transfer to a novel test context.     

Super-latent inhibition with delayed conditioned taste aversion testing

In three conditioned taste aversion experiments with rats, latent inhibition (LI) was examined as a function of the time interval (1 or 21 days) between the conditioning and the test phases. In Experiments 1 and 2, the effects of US intensity on LI were examined. LI increased in the 21-day condition, as compared with the 1-day condition, with medium and high US intensity, but not with weak US intensity. Groups not preexposed to the CS flavor had similar aversions when testing was conducted 1 day after conditioning, as compared with 21 days. In Experiment 3A, delay-induced super-LI was obtained when the delay was spent in the home cage and the experimental stages took place in a different context (as in Experiments 1 and 2). In Experiment 3B, when all the stages, including the delay period, were conducted in the home cage, there was no super-LI effect. The modulation of delay-induced super-LI as a function of US intensity and context extinction is discussed in relation to association deficit and retrieval interference theories of LI.     

Temporal coding affects transfer of serial and simultaneous inhibitors

In three experiments with rats, the temporal relationships under which a conditioned inhibitor would transfer its inhibitory potential to an independently trained excitor in a summation test were investigated. Each experiment varied the temporal relationship between the inhibitor and the transfer excitor at test (serial or simultaneous) and, in addition, manipulated either the inhibitor-training excitor (serial or simultaneous), training excitor-unconditioned stimulus (US) (trace or delay), or the transfer excitor-US (trace or delay) temporal relationships. Conditioned inhibition was found only when the no-US expectation evoked by the conditioned inhibitor was temporally aligned with the US expectation evoked by the transfer excitor, independent of whether the inhibitor was trained as a serial or simultaneous signal for US omission. Results are discussed in terms of the temporal coding hypothesis and the comparator hypothesis.     

Dissociation of conditioned appetitive and consummatory sexual behavior: Satiation and extinction tests

Sexual responses were conditioned in male Japanese quail using the opportunity to copulate with a female as the unconditioned stimulus (US). The conditioned stimulus (CS) was a 3-D object made of a taxidermically prepared female quail head mounted on a terry-cloth body. Both appetitive conditioned responses (approach and proximity to the CS) and consummatory conditioned responses (mount and cloacal contact directed toward the CS) developed when 2-min presentations of the CS were followed immediately by the US, but not when the CS and US were separated by trace intervals of 10 or 20 min (Experiment 1). Postconditioning sexual satiation suppressed conditioned cloacal contact responses more than conditioned approach to the CS (Experiment 2), and “acute” extinction suppressed both conditioned mounting and conditioned cloacal contact responses more than conditioned approach to the CS (Experiment 3). These results demonstrate a functional dissociation between conditioned appetitive and consummatory responses and imply that the motivational and/or associative mechanisms underlying the two types of behavior are distinct.     

Enhancement of conditioned inhibition via an extinction treatment

Rats were used in a conditioned-suppression paradigm to determine whether an extinction treatment would enhance a moderately developed conditioned inhibitor (CS?). To dissipate unconditioned suppression to the training stimuli, the subjects were first habituated to the stimuli and then given Pavlovian conditioned-inhibition (CI) training involving reinforced presentations of a clicker and nonreinforced compound presentations of that stimulus and the intended CS?, either a light or a tone. Thereafter, experimental subjects received presentations of their CS? by itself, whereas controls received no further training. Following the occurrence and loss of conditioned suppression to the CS? in the extinction phase, summation and retardation tests showed enhanced CI for the experimental subjects relative to both the controls and their own earlier levels of inhibitory performance. In fact, the enhanced inhibition for the experimental subjects approximated that shown by a comparison group for which the CS? had been strongly developed as an inhibitor. These findings suggest that an excitatory representation is associated with the CS? early in CI training, and that subsequent presentations of the CS? by itself strengthen its inhibitory effect by allowing it to be nonreinforced in the presence of that representation.     

Circadian-temporal context and latent inhibition of conditioned taste aversion: Effect of restriction in the intake of the conditioned taste stimulus

Latent inhibition of conditioned taste aversion (CTA) is sensitive to changes in the temporal context. A change in the time of day of conditioning with respect to the time of day of the preexposure can disrupt the latent inhibition. This contextual change in the time of day may reveal a temporal specificity of latent inhibition. The optimum procedure to induce this temporal specificity is not well established. For example, it has been shown that a long period of habituation to temporal contexts is one factor that can determine the effect. However, the experimental conditions on the conditioning day that facilitate this phenomenon are unknown. The aim of this study is to elucidate whether a restriction in the intake of the conditioned taste stimulus affects the temporal specificity of latent inhibition. Two main groups of Wistar rats were tested in a latent inhibition of CTA paradigm, in which the temporal specificity of this phenomenon was analyzed by a change in the time of day of conditioning. The intake of the taste stimulus was restricted in the conditioning day in one of the groups, but this restriction was not applied in the other group. The results indicated temporal specificity of latent inhibition only in the group without restriction, but not in the group with limitation in the intake of the taste stimulus during conditioning. These findings can help to elucidate the characteristics of the procedure to induce temporal specificity of latent inhibition.     

Efficient coding of information: Huffman coding

In his classic paper of 1948, Claude Shannon considered the problem of efficiently describing a source that outputs a sequence of symbols, each associated with a probability of occurrence, and provided the theoretical limits of achievable performance. In 1951, David Huffman presented a technique that attains this performance. This article is a brief overview of some of their results.     

智力落后者的记忆的信息加工研究

对智力落后者的瞬间记忆(VSIM)、初级记忆(PM)、二级记忆(SM)和三级记忆(TM)的研究表明，智力落后者的记忆加工在输入、储存和输出方面存在困难，而组织策略使用的缺乏也是导致其智力低下的一个因素。     

Staff Preferences in Children with Mental Retardation

Staff at a residential facility for children with mental retardation rated their most‐preferred and least‐preferred children on a list of child characteristics. Staff‐perceived characteristics that differed significantly between the most‐ and least‐preferred children were subjective traits involving physical attributes, mood, behaviour, and social qualities. The remaining characteristics comprised objective developmental traits that did not differentiate the two groups. Small children were more likely to be rated most‐preferred, and large children least‐preferred. Staff tended to discount positive traits in their least‐preferred children and tolerate negative attributes in their most‐preferred children. Some children were rated as both most‐ and least‐preferred by different caregivers. These findings add to the understanding of staff perceptions and attitudes and have implications for intervention.     

Divergence of conditioned eyeblink and conditioned fear in backward Pavlovian training

Two experiments of Pavlovian conditioning with rabbits evaluated the effects of initiating or continuing a conditioned stimulus (CS) after a paraorbital unconditioned stimulus (US). In Experiment 1, backward pairings, in which a CS came on after the US, produced a CS that appeared inhibitory on a measure of eyeblink conditioning but excitatory on a potentiated-startle measure of conditioned fear. In Experiment 2, extending the duration of a CS that came on prior to the US, so that it continued after the US, decreased eyeblink conditioned responses, whereas it increased conditioned fear. The data from the two experiments confirm and extend those of Tait and Saladin (1986), supporting the suppositions of AESOP (Wagner & Brandon, 1989) that conditioned eyeblink and conditioned fear can be dissociated under various temporal relationships between the CS and US.     

论反倾销立法中的实质性阻碍损害标准

实质性阻碍国内产业的建立是反倾销损害认定的一种具体情形。它最早出现在美国的国内立法中,并由于美国的影响而进入GATT/WTO体系。在美国的实践中,已经发展出一些关于判断实质性阻碍成立的规则,而欧盟仅有的一起案例,没有形成一般性做法。因为产业原因、费用原因和规定的不明确,实质性阻碍适用的很少。中国是反倾销的受害大国,实质性阻碍标准对我国具有重要意义。我国现有的立法不完善,应从实体和程序两方面加以改进。     

培智学校课程改革的实践研究

目前,培智学校的课程已越来越不能适应学生及教学的需要,课程改革已经成为所有弱智学校不可回避的教育改革重点.本文阐述了培智学校课程改革的原因、相关理论与实践,并介绍了北京市海淀培智学校课程改革的实验及其效果,初步摸索出一套弱智学校适合每个学生的课程及其实施方法,希望能对我国培智学校课程改革提供借鉴.     

PASS理论在智力落后研究领域中的应用

近年来,智力落后的定义多次修订,智力落后的成因及智力落后者的缺陷究竟在何处,一直是心理学界争论的焦点问题。本文从PASS理论入手,分析了智力落后的成因和本质,揭示了智力落后研究的认知心理学新走向,为今后智力落后研究的进一步深化提供理论参考。     

Dissociation of the blocking of conditioned eyeblink and conditioned fear following a shift in US locus

Two experiments with rabbits investigated the concordance of two measures of conditioning, eyeblink and potentiated startle, during a blocking sequence with paraorbital shock reinforcement. In both, a shift in the locus of shock from one eye to the other between the conditioning of an element and a compound of that element and a new cue had differential effects on the two measures of conditioning to the new cue. When the shock was unchanged, diminished conditioning in relation to controls (i.e., blocking) was observed on both measures. When the shock was changed, little conditioning was observed in startle, but control-equivalent amounts were observed in eyeblink (i.e., blocking occurred on the former but not the latter). The results are interpreted as showing a dissociation of the associative learning involving the emotive features of Pavlovian reinforcers and that involving the remaining sensory-perceptual features, and more compatible with a diminished US-processing, than with a CSprocessing, view of blocking.