Associative structure of second-order conditioning in humans

Second-order conditioning (SOC; i.e., conditioned responding to S2 as a result of S1–US pairings followed by S2–S1 pairings) is generally explained by either a direct S2→US association or by an associative chain (i.e., S2→S1→US). Previous research found that differences in responses to S2 after S1 was extinguished often depended on the nature of the S2–S1 pairings (i.e., sequential or simultaneous). In two experiments with human participants, we examined the possibility that such differences result from S1 evoking S2 during extinction of S1 following simultaneous but not sequential S2–S1 pairings. This evocation of S2 by S1 following simultaneous pairings may have paired the evoked representation of S2 with absence of the outcome, thereby facilitating mediated extinction of S2. Using sequential S2-S1 pairings, both Experiments 1 and 2 failed to support this account of how extinction of S1 reduced responding to S2. Experiment 1 found that extinguishing S1 reduced responding to S2, while extinguishing S2 had little effect on responses to S1, although forward evocation of S1 during extinction of S2 paired the evoked representation of S1 with absence of the outcome. In Experiment 2, evocation of S2 during S1 nonreinforced trials was prevented because S2–S1 pairings followed (rather than proceeded) S1-alone exposures. Nevertheless, responding to S2 at test mimicked S1 responding. Responding to S2 was high in the context in which S1 had been reinforced and low in the context in which S1 had been nonreinforced. Collectively, these experiments provide additional support for the associative-chain account of SOC.     

Differential second-order aversive conditioning using contextual stimuli

Two experiments were conducted to determine if contextual stimuli used as S₂ in a higher-order differential conditioning procedure would control the performance of rats. Discrete stimuli were first paired with footshock in a separate training context. During second-order training, a shock-associated discrete stimulus was presented in one of two discriminable observation chambers. Over 4 days of training, subjects engaged in more freezing in the context associated with an excitatory discrete S₁, relative to a context in which no discrete stimulus, or a stimulus that had been explicitly unpaired with shock delivery, was presented. After acquisition of the second-order discrimination, animals were returned to the original training context where they received a “signaled inflation” treatment designed to change the current value of S₁, and the US. This postconditioning manipulation did not selectively affect performance of defensive freezing or conditional analgesia in S₂.     

Temporal integration in second-order conditioning and sensory preconditioning

Lick suppression experiments with rats revealed that the magnitude of both second-order conditioning (Experiment 1) and sensory preconditioning (Experiment 2) was superior when that conditioning was based on backward (US→CS) relative to forward (CS→US) first-order pairings of a CS and US. The superiority of backward relative to forward first-order conditioning on suppression to the higher order cues can be understood by assuming that the magnitude of higher order conditioning was determined by a memory representation of the higher order cues that provided information about the expected temporal location of the US. The results suggest that temporal information such as order between paired CSs and USs was encoded, preserved, and integrated with memory for the higher order stimuli. The relevance of these findings to memory integration in Pavlovian learning, the temporal coding hypothesis (Barnet, Arnold, & Miller, 1991; Matzel, Held, & Miller, 1988), backward excitatory conditioning, and the associative structure that underlies second-order Pavlovian fear conditioning are discussed.     

Signaling functions of the second-order CS: Partial reinforcement during second-order conditioning of the pigeon’s keypeck

The signaling function of the second-order CS (S2) was manipulated in second-order autoshaping by arranging a partial reinforcement schedule. S2 was paired with a well-conditioned first-order CS (SI) on a continuous reinforcement or a 25% reinforcement schedule in different groups. Schedule of reinforcement did not influence the number of S2-S1 pairings required to establish keypecking to S2. However, in the postacquisition sessions, responding to S2 was initially weaker but persisted for many more sessions on the 25% schedule than on the 100% schedule. The data indicate that S2-S1 pairings are responsible both for the acquisition of second-order keypecking to S2 and for the subsequent conversion of S2 into an inhibitory stimulus.     

分块矩阵行列式的一些结果

借助准三角形分块矩阵的行列式值的结果及分块矩阵的广义消元法变换,不改变其行列式值的性质,证明了分块矩阵的行列式的几个更一般结果,并列举了两个应用实例。     

Multiple determinants of transfer of evaluative function after conditioning with free-operant schedules of reinforcement

The aim of the four present experiments was to explore how different schedules of reinforcement influence schedule-induced behavior, their impact on evaluative ratings given to conditioned stimuli associated with each schedule through evaluative conditioning, and the transfer of these evaluations through derived stimulus networks. Experiment 1 compared two contrasting response reinforcement rules (variable ratio [VR], variable interval [VI]). Experiment 2 varied the response to reinforcement rule between two schedules but equated the outcome to response rate (differential reinforcement of high rate [DRH] vs. VR). Experiment 3 compared molar and molecular aspects of contingencies of reinforcement (tandem VIVR vs. tandem VRVI). Finally, Experiment 4 employed schedules that induced low rates of responding to determine whether, under these circumstances, responses were more sensitive to the molecular aspects of a schedule (differential reinforcement of low rate [DRL] vs. VI). The findings suggest that the transfer of evaluative functions is determined mainly by differences in response rate between the schedules and the molar aspects of the schedules. However, when neither schedule was based on a strong response reinforcement rule, the transfer of evaluative judgments came under the control of the molecular aspects of the schedule.     

Reward sequence and reinforcement level as determinants of S− behavior in differential conditioning

In two differential conditioning experiments, groups of 10 rats each differed with respect to average reward and schedule of reward received in S+. Nonreward (N) occurred on all S? trials. In both experiments, extinction of responding to S? (resistance to discrimination) was extensively regulated by reward sequence and was largely independent of average reward. In Experiment 1, resistance to discrimination was a function of transitions from N to rewarded (R) trials (N-R transitions). In Experiment 2, resistance to discrimination was increased by large reward on the R trial of N-R transitions and decreased by large reward on the R trial of R-N transitions. These schedule effects on resistance to discrimination parallel the effects of comparable schedules on resistance to extinction following partial reinforcement. The results are discussed in terms of sequential theory, reinforcement level theory, and their implications for various schedule manipulations that have previously shown S? behavior to be inversely related to average reward in S+.     

Response deprivation and response satiation as determinants of instrumental performance: Some data and theory

Sixteen human subjects were presented with an instrumental task in which pressing a button to produce a visual stimulus was followed by an auditory stimulus. Half of the subjects were assigned to a condition under which pressing the button at the subject’s operant level produced less of the auditory stimulus than the subject would normally choose to receive. For the others, pressing the button at operant level produced more of the auditory stimulus than the subject would choose. Subjects in the former condition showed increases in instrumental performance; those in the latter showed decreases. The results indicated that the rewarding or punishing effects of an event depend upon the relation of the instrumental contingency to the subject’s unconstrained behavior.     

Conditioning of tentacle lowering in the snail (Helix aspersa): Acquisition, latent inhibition, overshadowing, second-order conditioning, and sensory preconditioning

In a series of related experiments, we studied associative phenomena in snails (Helix aspersa), using the conditioning procedure of tentacle lowering. Experiments 1A and 1B demonstrated a basic conditioning effect in which the pairing of an odor (apple) as the conditioned stimulus (CS) with the opportunity to feed on carrot as the unconditioned stimulus (US) made snails exhibit increased levels of tentacle lowering in the presence of the CS. Experiments 2 and 3 showed that the magnitude of the conditioning was reduced when snails were exposed to the CS prior to the conditioning trial (a latent inhibition effect). Experiment 4 examined the effects produced by pairing a compound CS (apple—pear) with food presentations and demonstrated the existence of an overshadowing effect between the two odors. Experiment 5 revealed that pairing one CS with another previously conditioned stimulus increased tentacle lowering to the new CS (a second-order conditioning effect). Finally, Experiment 6 showed that pairing two odors prior to conditioning of one of them promoted an increase in tentacle lowering in response to the other (a sensory preconditioning effect). The results are discussed in terms of an associative analysis of conditioning and its implications for the study of cognition in invertebrates.     

求解大型稀疏二次特征值问题的精化的二阶Arnoldi方法

利用精化投影原则,我们对求解二次特征值问题的二阶Arnold i方法(SOAR)进行改进,提出了精化的二阶Arnold i方法,并给出一个实用算法,最后给出一个数值算例,说明算法的有效性.     

Second-order conditioning: Different outcomes in fear and eyelid conditioning

Second-order conditioning has been frequently observed with the fear response but not with the eyelid response. The present experiments manipulated the temporal relationship between the second-order and first-order stimulus on second-order conditioning trials. Our results indicated that a trace second-order procedure is not effective with either response system. Second-order fear conditioning was most prominent when the second-order CS terminated at the onset of the first-order CS. This arrangement, however, did not produce second-order eyelid CRs. In eyelid conditioning, the second-order CS appears to inhibit responding to the first-order CS which immediately follows it.     

Classical-classical transfer: Effects of prior appetitive conditioning upon aversive conditioning in rabbits

An appetitive-ayersive transfer experiment with rabbits determined that prior paired and unpaired tone CS and water US presentations, given in jaw-movement (JM) conditioning, respectively facilitated and retarded the acquisition of the nictitating membrane (NM) CR when the tone was subsequently paired with a shock US. In addition, the unpaired tone and water deliveries reduced the level of JM conditioning that was undertaken following the completion of NM CR acquisition. Finally, the reacquisition of the NM CR was accompanied by a large savings effect in contrast to the failure of the JM CR to display reacquisition savings. When the present findings are compared to the results of previous work addressing the influence of prior NM conditioning procedures upon subsequent JM CR acquisition, an asymmetry in appetitive-aversive interactions is indicated. This asymmetry encourages a reinterpretation of the opponent-process explanation of appetitive-aversive interactions. Moreover, the observed effects of the unpaired CS suggest the operation of a salience factor.     

Classical conditioning in paramecia

SingleParamecium caudatum were conditioned by pairing ac-generated electric shock (US) with a vibratory stimulus (CS) produced by an auditory speaker. Naive paramecia subjected to shock reliably exhibited a backwards jerk and axial spinning similar to the avoiding reaction described by Jennings in 1904. Such responses did not occur initially to CS alone, but increasingly appeared during the CS period preceding shock pairing (delayed conditioning paradigm). Control subjects given the CS and UCS at the same intervals, but explicitly unpaired, did not show a sustained increase of responses to the CS alone. Short-term memory was demonstrated by subjects first conditioned and then presented CS alone during extinction. These subjects were readily reconditioned. Paramecia trained and stored for 24 h showed reliable memory savings as compared to stored control subjects. Other paramecia were differentially conditioned by training with two CSs. Following the recommendations of Rescorla (1967), a procedure was designed for truly random presentation of the CS and UCS as an additional control for pseudoconditioning. Single paramecia were conditioned with intervals between CSs randomly ranging from 8 to 32 sec. Control subjects received the same number of CSs and UCSs, which were administered independently and randomly during the same total session duration. Thus, CS and UCS were occasionally paired for control subjects. The responses to CS in the conditioned group were anticipatory conditional responses due to the pairing contingency and not wholly due to pseudoconditioning.     

Blocking of first- and second-order autoshaping in pigeons

In Experiment 1, the development of autoshaped pecking to a keylight signaling food was blocked if the keylight was presented only in conjunction with another stimulus already established as a signal for food, even though the blocking stimulus (either an overhead light or a train of clicks) never elicited pecking itself. In Experiment 2, pigeons came to peck a white keylight which signaled the presentation of a red keylight which had earlier been established as a first-order signal for food, but this second-order autoshaping was blocked if the white keylight was presented only in conjunction with the houselight or clicker which had previously signaled the presentation of the first-order stimulus. Second-order autoshaping was thus blocked in the same way as was first-order autoshaping.     

二阶线性脉冲微分方程的振动性

研究一类二阶线性脉冲微分方程解的振动性,揭示了此类方程与相应的非脉冲方程在振动性方面的联系．     

Comparison of auditory and visual conditioning stimuli in delay eyeblink conditioning in healthy young adults

Classical eyeblink conditioning (EBC) has been widely used to probe cerebellar function in humans and nonhuman mammals. Although the neural pathways governing behavior in this task are well understood and fairly discrete, it remains unclear in the human literature how conditioned stimuli (CSs) of different modalities (e.g., visual and auditory) influence the exhibition of conditioned responses (CRs). In the present study, therefore, CRs to a visual CS and an auditory CS were examined with the single-cue delay EBC procedure. An initial experiment (N=61) was conducted to identify visual and auditory stimuli that had equal perceived intensities. Using these perceptually equivalent stimuli, a second group of 25 subjects completed auditory and visual EBC procedures in two testing sessions 5–8 days apart. Whereas the acquisition of CRs was similar between the CS modality conditions, the timing of the CRs differed such that earlier CR onset and peak latencies were associated with the visual CS. In addition, CR timing improved across testing sessions, as indicated by the later CR peak latencies exhibited during the second testing session, as compared with the first.     

Socioeconomic determinants of academic achievement

This study aims to investigate the relationship between academic achievement and the socioeconomic characteristics of elementary school 7th grade students in Burdur. The population of the study are 7th grade students who had education at elementary schools in Burdur in the 2007?C2008 academic year. Two staged sampling was chosen as suitable for the aim of research. In the first stage, settlements were chosen with the random settlement group sampling method. In the second stage, schools in chosen settlements were picked up with the random method considering the number of students who have taken SBS examination. Socioeconomic variables of students generally explain 39.2?% of SBS points of student. When standard beta values are observed, variables which have the most effect on the SBS points of students are: attending a course or having private lessons, father??s education, the average monthly income per capita, attending a course or having private lessons and mother??s education.     

几类二阶非线性微分方程的可积类型

给出了几类二阶非线性微分方程可积条件，并得出求解方程的通解公式。     

Context effects on conditioning,extinction, and reinstatement in an appetitive conditioning preparation

Three experiments with rat subjects examined the effects of contextual stimuli on performance in appetitive conditioning. A 10-sec tone conditioned stimulus (CS) was paired with a food-pellet unconditioned stimulus (US); conditioning was indexed by the observation of headjerking, a response of the rat to auditory stimuli associated with food. In Experiment 1, a context switch following initial conditioning did not affect conditioned responding to the tone; however, when the response was extinguished in the different context, a return to the original conditioning context “renewed” extinguished responding. These results were replicated in Experiments 2 and 3 after equating exposure to the two contexts (Experiment 2) and massing the conditioning and extinction trials (Experiment 3). The results of Experiment 1 also demonstrated that separate exposure to the US following extinction reinstates extinguished responding to the tone; this effect was further shown to depend at least partly on presenting the US in the context in which testing is to occur (Experiments 2 and 3). Overall, the results are consistent with previous data from aversive conditioning procedures. In either appetitive or aversive conditioning, the context may be especially important in affecting performance after extinction.     

Chemosensory-based contextual conditioning inHermissenda crassicornis

In two experiments, the marine molluskHermissenda crassicornis was exposed to context discrimination training. In one context, defined by the presence of a diffuse chemosensory stimulus (shellfish extract A), brief, unsignaled, unconditioned stimuli (USs; high-speed rotation) were presented; in a second context, defined by the presence of shellfish extract B, no USs were presented. Animals were then tested (at both 1.5 and 24 h) by exposing them to small pieces of the shellfish meat used to define the two contexts. The latency to strike at the meat served as an index of the context-US association. In Experiment 1, the latency to strike at the cue associated with rotation was reduced relative to both preconditioning strike latencies and the associatively neutral cue. However, in a two-choice test where the animals could approach the conditioned or neutral stimulus, the animals regularly avoided the stimulus paired with rotation. Moreover, if, following conditioning, the animals were presented with an unsignaled rotation in the conditioned context or the neutral context, the animals exhibited more effective defensive clinging (an unconditioned reflex normally elicited by rotation) in the conditioned context, suggesting that it “prepared” the animal for the aversive US. In total, these results demonstrate thatHermissenda is capable of making associations to diffuse background (contextual) stimuli. Moreover, the results suggest that pairing the chemosensory cue with an aversive US elicits a strike response inHermissenda when the animal is placed in forced contact with the cue and an active avoidance response when the animal can choose between that cue and a neutral cue.