An expectancy model of laboratory preparedness effects.

Experiments investigating differential unconditioned stimulus/stimuli (UCS) expectancy during fear-relevant (prepared) and fear-irrelevant (unprepared) stimuli revealed that (1) a UCS expectancy bias is apparent before conditioning, (2) initial differential UCS expectancy appears in spite of instructions informing the Ss of no UCS presentations, (3) differential UCS expectancies to fear-relevant and fear-irrelevant stimuli dissipate with continued nonreinforcement, (4) differential UCS expectancies may be translated into differential skin conductance responses (SCRs) under certain conditions, (5) both UCS expectancy and SCR measures show similar patterns of behavior in the traditional preparedness paradigm, and (6) experiencing conditioned stimulus/stimuli (CS)–UCS pairings appears to reinstate a UCS expectancy bias after it has extinguished. These results are discussed as support for an expectancy model of laboratory preparedness effects. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Conditioned diminution of the unconditioned skin conductance response.

During Pavlovian conditioning the expression of a conditioned response typically serves as evidence that an association between a conditioned stimulus (CS) and an unconditioned stimulus (UCS) has been learned. However, learning-related changes in the unconditioned response (UCR) produced by a predictable UCS can also develop. In the present study, we investigated learning-related reductions in the magnitude of the unconditioned skin conductance response (SCR). Healthy volunteers participated in a differential conditioning study in which one tone (CS+) was paired with a loud white-noise UCS and a second tone (CS?) was presented alone. In addition, probe trials that consisted of UCS presentations paired with the CS+ (CS + UCS) and CS? (CS ? UCS), as well as presentations of the UCS alone were included to assess UCR diminution. SCR and participants' expectations of UCS presentation were monitored during conditioning. Greater diminution of the UCR was observed to the UCS when it followed the CS+ compared to when it followed the CS? or was presented alone. Further, UCR amplitude showed an inverse relationship with the participants' ratings of UCS expectancy. However, conditioned UCR diminution was also observed independent of differential UCS expectancies. Our findings demonstrate conditioned diminution of the unconditioned SCR. Further, these findings suggest that although UCR amplitude is modified by conscious expectations of the UCS, conditioned diminution of the UCR can be expressed independent of learning-related changes in these expectations. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Conditioning with masked stimuli affects the timecourse of skin conductance responses.

In Pavlovian fear conditioning, an aversive unconditional stimulus (UCS) is repeatedly paired with a neutral conditional stimulus (CS). As a consequence, the subject begins to show conditional responses (CRs) to the CS that indicate expectation and fear. There are currently two general models competing to explain the role of subjective awareness in fear conditioning. Proponents of the single-process model assert that a single propositional learning process mediates CR expression and UCS expectancy. Proponents of a dual-process model assert that these behavioral responses are expressions of two independent learning processes. We used backward masking to block perception of our visual CSs and measured the effect of this training on subsequent unmasked performance. In two separate experiments we show a dissociation between CR expression and UCS expectancy following differential delay conditioning with masked CSs. In Experiment I, we show that masked training facilitates CR expression when the same CSs are presented during a subsequent unmasked reacquisition task. In Experiment II we show that masked training retards learning when the CS+ is presented as part of a compound CS during a subsequent unmasked blocking task. Our results suggest that multiple memory systems operate in a parallel, independent manner to encode emotional memories. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

In dubio pro defensio: Initial activation of conditioned fear is not cue specific.

This study explored the time course of conditioned fear response expression. Two neutral male facial expressions served as conditioned stimuli (CS) in a differential trace conditioning that involved either an aversive (n=14) or a nonaversive (n=12) unconditioned stimulus (UCS) in a between-subjects design. Skin conductance response (SCR) to the CSs and startle response magnitudes to acoustic probes presented at early (250 ms) or late (1,750 ms) probe times after CS onset were measured. As expected, conditioned SCR discrimination was observed in both aversive and nonaversive learning, whereas the conditioned potentiation of the startle response was only observed for the aversive UCS condition. Interestingly, conditioned startle discrimination was specific for the later probe time. In contrast, conditioned fear potentiation of the startle response at the early probe time was equally pronounced for CS+ and CS-. These findings suggest that fear-eliciting neural structures are rapidly activated in fear learning, whereas the expression of inhibitory conditioning requires more time, presumably reflecting the involvement of cortical top-down control processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

McCollough effects as conditioned responses? Reply to Allan and Siegel.

Replies to the critique by L. G. Allan and S. Siegel (see record 1987-09282-001) of the author's (see record 1984-30511-001) position by examining their evidence in terms of longevity and decay, relearning and the effects of practice, conditioned stimulus/stimuli (CS)/unconditioned stimulus/stimuli (UCS) contingency, awareness of the stimuli, acquisition process, temporal relations, and other components. It is concluded that Allan and Seigel's evidence does not support a classical conditioning model. (34 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Under what conditions can human affective conditioning occur without contingency awareness? Test of the evaluative conditioning paradigm.

The role of conscious cognitive processes in human affective conditioning remains controversial, with several theories arguing that such conditioning can occur without awareness of the conditioned stimulus (CS)-unconditioned stimulus (UCS) contingency. One specific type of affective conditioning in which unaware conditioning is said to occur is "evaluative conditioning." The present experiment tested the role of contingency awareness by embedding an evaluative conditioning paradigm in a distracting masking task while obtaining, in addition to subjective ratings of affect, both psychophysiological (skin conductance and startle eyeblink) and indirect behavioral (affective priming) measures of conditioning, along with a trial-by-trial measure of awareness from 55 college student participants. Aware participants showed conditioning with all of the measures; unaware participants failed to show conditioning with all measures. The behavioral, neurophysiological, and therapeutic implications of these findings are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Stimulation at a site of auditory-somatosensory convergence in the medial geniculate nucleus is an effective unconditioned stimulus for fear conditioning.

The medial division of the medial geniculate nucleus (MGm) and the posterior intralaminar nucleus (PIN) are necessary for conditioning to an auditory conditioned stimulus/stimuli (CS), receive both auditory and somatosensory input, and project to the amygdala, which is involved in production of fear conditioned responses (CRs). If CS–unconditioned stimulus (UCS) convergence in the MGm-PIN is critical for fear conditioning, then microstimulation of this area should serve as an effective UCS during classical conditioning, in place of standard footshock. Guinea pigs underwent conditioning (40–60 trials) using a tone as the CS and medial geniculate complex microstimulation as the UCS. Conditioning bradycardia developed when the UCS electrodes were in the PIN. However, microstimulation was not an effective UCS for conditioning in other parts of the medial geniculate or for sensitization training in the PIN or elsewhere. Learning curves were similar to those found previously for footshock UCS. Thus, the PIN can be a locus of functional CS–UCS convergence for fear conditioning to acoustic stimuli. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Impact of Healthy Aging on Awareness and Fear Conditioning.

Fear conditioning has provided a useful model system for studying associative emotional learning, but the impact of healthy aging has gone relatively unexplored. The present study investigated fear conditioning across the adult life span in humans. A delay discrimination task was employed using visual conditioned stimuli and an auditory unconditioned stimulus. Awareness of the reinforcement contingencies was assessed in a postexperimental interview. Compared with young adult participants, middle-aged and older adults displayed reductions in unconditioned responding, discriminant conditioning, and contingency awareness. When awareness and overall arousability were taken into consideration, there were no residual effects of aging on conditioning. These results highlight the importance of considering the influence of declarative knowledge when interpreting age-associated changes in discriminative conditioned learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Rapid reacquisition in conditioning of the rabbit's nictitating membrane response.

Reacquisition after extinction often appears faster than original acquisition. However, data from conditioned suppression studies indicate that this effect may arise from spontaneous recovery and reinstatement of unextinguished contextual stimuli related to the unconditioned stimulus/stimuli (UCS). In the present experiments using the rabbit nictitating membrane preparation, spontaneous recovery was eradicated before reacquisition training. UCS contextual stimuli were controlled by retaining the UCS during extinction through explicit unpairings of the conditioned stimulus/stimuli (CS) and UCS. Attempts were also made to drive the associative strength of the CS into the inhibitory region by differential conditioning and conditioned inhibition procedures. In all cases, reacquisition was very rapid in comparison with a rest control. The results are discussed with respect to their implications for CS and UCS processing models of conditioning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Consequences of response-contingent change in unconditioned stimulus intensity upon the rabbit (Oryctolagus cuniculus) nictitating membrane response.

In a between-groups design using a total of 84 naive male and female rabbits, an instrumental contingency was superimposed on classical conditioning of the nictitating membrane response. Ss were exposed to a tonal conditioned stimulus (CS) and, if no conditioned response (CR) occurred, a 5.0-ma paraorbital electric shock unconditioned stimulus (UCS). UCSs of 5.0, 3.3, 1.7, and 0.0 ma, respectively, were contingent on occurrence of a CR in the CS-UCS interval for Ss in the 4 groups of the experiment. The group exposed to contingent UCS omission differed from the other 3 groups in percentage CR, onset latency, amplitude, and 2 indices of CR form, and those 3 groups generally did not differ significantly among themselves on these dependent variables. Results are interpreted to be contrary to "law of effect" formulations of classical conditioning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Analysis of the associative and occasion-setting properties of contexts participating in a Pavlovian discrimination.

In 3 conditioned suppression experiments with 64 male Wistar rats, contextual control of performance to a conditioned stimulus (CS) was generated by alternating CS–unconditioned stimulus (UCS) pairings in Context A with CS presentations alone in Context B. Suppression to the CS during discrimination training and during tests of the CS in a 3rd context suggested that Contexts A and B had both acquired an ability to modulate performance. Whether the contexts modulated behavior through their direct associations with the UCS or through their abilities to occasion-set the CS–UCS relation was explored. There was no evidence of direct context–UCS associations in either context. Repeated extinction exposures to Context A following discrimination training did not affect its ability to modulate CS performance. Excitatory conditioning of Context B, however, abolished its ability to modulate. It is suggested that demonstrable context–UCS associations are not necessary for the contextual control of CS performance and that although the parallel is not perfect, contexts share several critical properties with stimuli that occasion-set CS–UCS relations. The possible role of configural conditioning is discussed. (54 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comparative electrophysiologic findings between responders and nonresponders to class III antiarrhythmic drugs among patients with ventricular tachyarrhythmia

Rabbits received conditional discrimination training using contextual stimuli to set the occasion for stimulus pairings during eyelid conditioning. Specifically, animals were exposed to either the presence or the absence of an oscillating chamber light throughout the intertrial interval (50 +/- 10 s). For half the animals, this light signaled paired presentations of a discrete tone conditioned stimulus (CS) and air puff unconditioned stimulus (US) while darkness signaled presentations of only the tone CS. The remaining animals experienced the opposite contextual relationship to the conditioning stimuli. These trial types occurred pseudo-randomly across a session, with all transitions between contextual settings (i.e., light or dark) taking place immediately at the CS-US offset. Under these conditions, animals successfully utilized the contextual stimuli as conditional cues for differential responding to the shared CS. Moreover, both light and dark were equally effective as discriminative stimuli. A subset of animals received further training in which the contextual contingency was removed by restricting all conditioning to the CS-alone context. Without the contingency in place, subsequent CS presentations (paired and CS-alone) evoked equivalent conditioned responding across three sessions of training. Following the reinstatement of the contextual contingencies, discriminatory responding was immediately observed and returned to previous levels within three sessions. Finally, animals appeared to use the static representation of the conditional cue, rather than the phasic transition between cues, for discriminatory responding. These findings are discussed in terms of current neurobiological models of eyelid conditioning.     

Standard delay eyeblink classical conditioning is independent of awareness.

P. F. Lovibond and D. R. Shanks (see record 2002-00340-001) suggested that all forms of classical conditioning depend on awareness of the stimulus contingencies. This article considers the available data for eyeblink classical conditioning, including data from 2 studies (R. E. Clark, J. R. Manns, & L. R. Squire, 2001; J. R. Manns, R. E. Clark, & L. R. Squire, 2001) that were completed too recently to have been considered in their review. In addition, in response to questions raised by P. F. Lovibond and D. R. Shanks, 2 new analyses of data are presented from studies published previously. The available data from humans and experimental animals provide strong evidence that delay eyeblink classical conditioning (but not trace eyeblink classical conditioning) can be acquired and retained independently of the forebrain and independently of awareness. This conclusion applies to standard conditioning paradigms; for example, to single-cue delay conditioning when a tone is used as the conditioned stimulus (CS) and to differential delay conditioning when the positive and negative conditioned stimuli (CS+ and CS-) are a tone and white noise. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Mechanisms underlying retarded emergence of conditioned responding following inhibitory training: Evidence for the comparator hypothesis.

The comparator hypothesis posits that conditioned responding is determined by a comparison at the time of testing between the associative strengths of the conditioned stimulus/stimuli (CS) and stimuli proximal to the CS at the time of conditioning. The hypothesis treats all associations as being excitatory and treats conditioned inhibition as the behavioral consequence of a CS that is less excitatory than its comparator stimuli. Conditioned lick suppression by rats was used to differentiate 4 possible sources of retarded responding to an inhibitory CS. These include habituation to the unconditioned stimulus/stimuli (UCS), latent inhibition to the CS, blocking of the CS-UCS association by the conditioning context, and enhanced excitatory associations to the comparator stimuli. Prior research has demonstrated the 1st 3 phenomena. Therefore, we employed parameters expected to highlight the 4th one—the comparator process. In Exp I, our negative contingency training produced a conditioned inhibitor that passed inhibitory summation and retardation tests. In Exp II we found transfer of retardation from an inhibitory CS to a novel stimulus when the location where retardation-test training occurred was excitatory. In Exp III, extinction of the conditioning context attenuated retardation regardless of whether extinction occurred before or after the CS-UCS pairings of the retardation test. Exp IV demonstrated that habituation to the UCS did not contribute to retardation in the present case. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of contingency violations on the extinction of a conditioned fear inhibitor and a conditioned fear excitor.

In 4 experiments, 192 male Holtzman and Sprague-Dawley rats were used in a conditioned-suppression paradigm to assess the effects of contingency variations on responding to a conditioned stimulus (CS) inhibitor (CS–) and a conditioned stimulus excitor (CS+). In Exp I, various unconditioned stimulus/stimuli (UCS) frequencies were equated across the presence and absence of a CS– in the context of either background cues (continuous-trial procedure) or an explicit neutral event (discrete-trial procedure). With both procedures, a CS-alone treatment enhanced inhibition, whereas treatments involving 50 or 100% reinforcement for the CS– eliminated inhibition without conditioning excitation to that CS. The latter outcome also occurred in Exp II, with discrete-trial training equating considerably reduced UCS frequencies for the presence and absence of the CS–. In further evidence that inhibition was eliminated without conditioning excitation to the CS–, Exp III showed that a novel CS did not acquire excitation when 25, 50, or 100% reinforcement was equated across the presence and absence of that CS in the context of a discrete-trial event. Using the procedures of Exp I, Exp IV showed that a CS+ was extinguished by a CS-alone treatment but was substantially maintained by treatments involving 50 or 100% uncorrelated reinforcement. These effects for a CS+ and a CS– implicate CS–UCS contiguity, rather than contingency, as the factor determining the extinction of a CS. (33 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Conditioning the unconditioned response: Modification of the rabbit's (Oryctolagus cuniculus) unconditioned nictitating membrane response.

Conditioning-specific reflex modification (CRM) occurs when classical conditioning modifies responding to a unconditioned stimulus/stimuli (UCS) in the absence of a conditioned stimulus (CS). Three experiments monitored rabbit (Oryctolagus cuniculus) nictitating membrane unconditioned responses to 5 intensities and 4 durations of periorbital electrical stimulation before and after CS or UCS manipulation. CRM occurred after 12 days of CS-UCS pairings but not following unpaired CS/UCS presentations or restraint. CRM survived CS-alone and CS/UCS-unpaired extinction of the conditioned response (CR) but not presentations of the UCS alone, although CRs remained intact. Thus, CRs could be weakened without eliminating CRM and CRM could be weakened without eliminating CRs. Data indicate CRM is a reliable, associative effect that is more than a generalized CR and may not be explained by habituation, stimulus generalization, contextual conditioning, or bidirectional conditioning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Unawareness is more than a chance event: Comment on Lovibond and Shanks (2002).

P. F. Lovibond and D. R. Shanks (see record 2002-00340-001) suggested that expectancy of the unconditional stimulus and emotional ratings are valid indexes of awareness in Pavlovian conditioning and that participants are aware if they can discriminate the conditional stimuli. However, research suggests that processes that are irrelevant to awareness affect these measures. Further, as awareness refers to conscious experience, a valid measure needs to index subjective state rather than discrimination ability. In support research using subjective measures has demonstrated qualitatively different effects depending on whether participants reported being aware or unaware of the stimuli. In this research, participants reported being unaware of the stimuli even though they were clearly able to discriminate the stimuli. These findings question the validity of Lovibond and Shanks' concept of awareness and their suggestion of a close association between conditioning and awareness. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

经典条件反射中条件刺激的信号作用及其应用

巴甫洛夫的经典条件反射包括条件刺激与无条件刺激，条件刺激起作用的条件是条件刺激成为无条件刺激出现的信号，条件刺激的信号作用受很多因素影响，运用经典条件反射原理解决各种问题的时候要根据这些影响因素安排条件刺激与无条件刺激。经典条件作用原理可运用于解释心理障碍、行为治疗、辅助医疗、幼儿护理、学生行为管理、动物保护和市场营销等领域。     

Septal correlates of conditioned inhibition and excitation in rats.

Recorded multiple-unit activity in the lateral septum of rats during Pavlovian differential conditioning. In Exp I, 14 male Sprague-Dawley rats received a classical aversive discrimination paradigm, while 11 Ss were presented with a control procedure in which the UCS (shocks) was administered randomly with regard to the CS. Septal unit activity increased during presentations of the conditioned inhibitor and was markedly suppressed during presentations of the conditioned excitor in the conditioning-group Ss and not in controls. Baseline activity remained unchanged in the conditioning group but was suppressed in the random control group. Furthermore, termination of the aversive stimuli was marked by a burst of firing in the conditioning group, but no such rebound was seen in the control group. In Exp II (6 Ss), a classical appetitive discrimination paradigm was given, in which septal unit activity increased in the presence of the conditioned excitor and was suppressed in the presence of the conditioned inhibitor. Results indicate a role for the septum in the relief of aversive states. (16 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Human blink startle during aversive and nonaversive Pavlovian conditioning.

Potentiation of blink startle during aversive and nonaversive Pavlovian single-cue conditioning was assessed in human Ss. In Exp 1 (N?=?89), the conditioning group received paired presentations of a visual CS and an unconditioned stimulus/stimuli (UCS), whereas the control group was presented with a random sequence. The UCS was an electric shock for half the Ss and a nonaversive reaction time (RT) task for the other half. Electrodermal conditioning was evident regardless of the nature of the UCS, but blink potentiation was found only in the conditioning group that had been trained with the aversive UCS. These results were replicated in Exp 2 (N?=?65), in which a nonaversive UCS of increased motivational significance was used. Thus, only aversive conditioning seems to affect the affective valence of the CS, at least as reflected by changes in a skeletal reflex. (PsycINFO Database Record (c) 2010 APA, all rights reserved)