In Search of the Preference Reversal Zone.

A preference reversal is observed when a preference for a larger-later (LL) reward over a smaller-sooner (SS) reward reverses as both rewards come closer in time. Preference reversals are common in everyday life and in the laboratory and are often claimed to support hyperbolic delay-discounting models which, in their simplest form, can model reversals with only one free parameter. However, it is not clear if the temporal location of preference reversals can be predicted a priori. Studies testing model predictions have not found support for them, but they overlooked the well-documented effect of reinforcer magnitude on discounting rate. Therefore, we directly tested hyperbolic and exponential model predictions in a pre-registered study by assessing individual discount rates for two reinforcer magnitudes. We then made individualized predictions about pairs of choices between which preference reversals should occur. With 107 participants, we found (1) little evidence that hyperbolic and exponential models could predict the temporal location of preference reversals, (2) some evidence that hyperbolic models had better predictive performance than exponential models, and (3) in contrast to many previous studies, that exponential models generally produced superior fits to the observed data than hyperbolic models.

The Efficacy of Interdisciplinary Near-Peer Teaching Within Neuroanatomical Education-Preliminary Observations.

Near-Peer Teaching (NPT) is increasingly becoming an integral part of the medical curriculum. When considered alongside the increasing popularity of interdisciplinary education, it seems appropriate to explore NPT within an interdisciplinary context. In these observations, 3rd-year medical students taught 2nd-year psychology students neuroanatomy. The session was evaluated using three objective and subjective assays. A knowledge assessment test showed significant improvement after teaching, and there were significant improvements on self-perceived knowledge/attitudes towards neuroanatomy, as well as positive feedback on the use of NPT. These observations evidence the successful use of Interdisciplinary Near-Peer Teaching (INPT) within a neuroanatomical curriculum. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s40670-021-01238-6.

Stable Individual Differences in Occasion Setting.

In the current investigation, we classified participants as inhibitors or non-inhibitors depending on the extent to which they showed conditioned inhibition in a context that had been used for extinction of a conditioned response. This classification enabled us to predict participant responses in a second experiment which used a different design and a different experimental task. In the second experiment a feature-negative discrimination survived reversal training of the feature to a greater extent in the non-inhibitors than in the inhibitors and this result was supported by Bayesian analyses. We propose that the fundamental distinction between inhibitors and non-inhibitors is based on a tendency to utilize first-order (direct associations) or second-order (occasion-setting) strategies when faced with ambiguous information and that this classification is a stable individual differences attribute.

Flexible Configural Learning of Non-Linear Discriminations and Detection of Stimulus Compounds.

Previous work showed that prior experience with discriminations requiring configural solutions (e.g., biconditional discrimination) confers an advantage for the learning of new configural discriminations (e.g., negative patterning) in comparison to prior experience with elemental discriminations. This effect is well established but its mechanism is not well understood. In the studies described below we assessed whether the saliences of configural and element cues were affected by prior training. We observed positive transfer to a new configural discrimination after configural pre-training but we were unable to find evidence for changes in cue salience using a signal-detection task. Our results confirm previous work by demonstrating experience-dependent flexibility in cue processing but they also suggest that this flexibility occurs at a point in the stimulus processing pipeline later than 1-2 s after the presentation of stimulus inputs. (138 words).

Relative prediction error and protection from attentional blink in human associative learning.

The relationship between predictive learning and attentional processing was investigated in two experiments. During a learning procedure participants viewed rapid serial visual presentation (RSVP) of stimuli in the context of a choice-reaction-time (CRT) task. Salient stimuli in the RSVP streams were either predictive or non-predictive for the outcome of the CRT task. Following this procedure we measured attentional blink (AB) to the predictive and non-predictive stimuli. In Experiment 1, despite the use of a large sample and checks demonstrating the validity of the learning procedure and the AB measure, we did not observe reduced AB for predictive stimuli. In contrast, in Experiment 2, where the predictive stimuli occurred alongside salient non-predictive comparison stimuli, we did find less AB for predictive than for non-predictive stimuli. Our results support an attentional model of learning in which relative prediction error is used to increase learning rates for good predictors and reduce learning rates for poor predictors and provide confirmation of the AB learning effect.

Extinction produces context inhibition and multiple-context extinction reduces response recovery in human predictive learning.

Two experiments with human participants were used to investigate recovery of an extinguished learned response after a context change using ABC designs. In an ABC design, the context changes over the three successive stages of acquisition (context A), extinction (context B), and test (context C). In both experiments, we found reduced recovery in groups that had extinction in multiple contexts, and that the extinction contexts acquired inhibitory strength. These results confirm those of previous investigations, that multiple-context extinction can produce less response recovery than single-context extinction, and they also provide new evidence for the involvement of contextual inhibitory processes in extinction in humans. The foregoing results are broadly in line with a protection-from-extinction account of response recovery. Yet, despite the fact that we detected contextual inhibition, predictions based on protection-from-extinction were not fully reliable for the single- and multiple-context group differences that we observed in (1) rates of extinction and (2) the strength of context inhibition. Thus, although evidence was obtained for a protection-from-extinction account of response recovery, this account can not explain all of the data.

Revisiting the learning curve (once again).

The vast majority of published work in the field of associative learning seeks to test the adequacy of various theoretical accounts of the learning process using average data. Of course, averaging hides important information, but individual departures from the average are usually designated "error" and largely ignored. However, from the perspective of an individual differences approach, this error is the data of interest; and when associative models are applied to individual learning curves the error is substantial. To some extent individual differences can be reasonably understood in terms of parametric variations of the underlying model. Unfortunately, in many cases, the data cannot be accomodated in this way and the applicability of the underlying model can be called into question. Indeed several authors have proposed alternatives to associative models because of the poor fits between data and associative model. In the current paper a novel associative approach to the analysis of individual learning curves is presented. The Memory Environment Cue Array Model (MECAM) is described and applied to two human predictive learning datasets. The MECAM is predicated on the assumption that participants do not parse the trial sequences to which they are exposed into independent episodes as is often assumed when learning curves are modeled. Instead, the MECAM assumes that learning and responding on a trial may also be influenced by the events of the previous trial. Incorporating non-local information the MECAM produced better approximations to individual learning curves than did the Rescorla-Wagner Model (RWM) suggesting that further exploration of the approach is warranted.

Convergent results in eyeblink conditioning and contingency learning in humans: addition of a common cue does not affect feature-negative discriminations.

Previous human discrimination learning experiments with eyeblink conditioning showed that an increase in the similarity between the to-be-discriminated stimuli had no effect on the rate of learning. This result was at variance with data from other experiments which had used different paradigms and different stimulus materials. We therefore compared human discrimination learning in eyeblink conditioning and contingency learning using carefully matched procedures. Participants learned two feature-negative discriminations, A+/AB- and CD+/CDE-. Convergent results were obtained in both paradigms. Adding a common cue did not affect response differentiation, i.e. the A+/AB- discrimination and the CD+/CDE- discriminations were equivalent. These results support the notion that learning in both paradigms is based on the same principles. However, the overall pattern of results cannot be easily accommodated within associative learning theories based on the Rescorla-Wagner Model or on Pearce's Configural Model. The application of these models to current and previous data is discussed.

A differential role for neuropeptides in acute and chronic adaptive responses to alcohol: behavioural and genetic analysis in Caenorhabditis elegans.

Prolonged alcohol consumption in humans followed by abstinence precipitates a withdrawal syndrome consisting of anxiety, agitation and in severe cases, seizures. Withdrawal is relieved by a low dose of alcohol, a negative reinforcement that contributes to alcohol dependency. This phenomenon of 'withdrawal relief' provides evidence of an ethanol-induced adaptation which resets the balance of signalling in neural circuits. We have used this as a criterion to distinguish between direct and indirect ethanol-induced adaptive behavioural responses in C. elegans with the goal of investigating the genetic basis of ethanol-induced neural plasticity. The paradigm employs a 'food race assay' which tests sensorimotor performance of animals acutely and chronically treated with ethanol. We describe a multifaceted C. elegans 'withdrawal syndrome'. One feature, decrease reversal frequency is not relieved by a low dose of ethanol and most likely results from an indirect adaptation to ethanol caused by inhibition of feeding and a food-deprived behavioural state. However another aspect, an aberrant behaviour consisting of spontaneous deep body bends, did show withdrawal relief and therefore we suggest this is the expression of ethanol-induced plasticity. The potassium channel, slo-1, which is a candidate ethanol effector in C. elegans, is not required for the responses described here. However a mutant deficient in neuropeptides, egl-3, is resistant to withdrawal (although it still exhibits acute responses to ethanol). This dependence on neuropeptides does not involve the NPY-like receptor npr-1, previously implicated in C. elegans ethanol withdrawal. Therefore other neuropeptide pathways mediate this effect. These data resonate with mammalian studies which report involvement of a number of neuropeptides in chronic responses to alcohol including corticotrophin-releasing-factor (CRF), opioids, tachykinins as well as NPY. This suggests an evolutionarily conserved role for neuropeptides in ethanol-induced plasticity and opens the way for a genetic analysis of the effects of alcohol on a simple model system.

Reduced summation with common features in causal judgments.

In three experiments human participants received training in a causal judgment task. After learning which patterns were associated with an outcome, participants rated the likelihood of the outcome in the presence of a novel combination of the patterns. The first two experiments used two conditions in which two visual patterns were associated with the outcome. In one condition these patterns shared a common feature. The third experiment only used the common feature condition. According to an elemental theory (Rescorla & Wagner, 1972) the response to the novel test pattern should have exceeded that made to the individual training patterns, a summation effect, and this effect should have been reduced by the addition of a common feature. Summation was observed but since the common feature condition abolished, rather than merely reduced, summation the results were not consistent with the Rescorla-Wagner Model (RWM) nor with a configural alternative (Pearce, 1994). Instead, it is necessary to consider models which allow the possibility of both elemental and configural strategies in causal learning. The Replaced Elements Model (Wagner, 2003) is a development of the RWM which can best predict the patterns of summation and summation failure in these experiments.

Nicotine withdrawal and reward responsivity in a card-sorting task.

RATIONALE: Animal studies have demonstrated decreased reward responsivity during nicotine withdrawal (e.g., Epping-Jordan et al., Nature 393:76-79, 1998) and the Card Arranging Reward Responsivity Objective Test (CARROT) has recently been used to study the effect of nicotine withdrawal on reward responsivity in humans (e.g., Al-Adawi and Powell, Addiction 92:1773-1782, 1997; Powell et al., Biol Psychiatry 51:151-163, 2002). We investigated a suggestion that nicotine withdrawal may have additional reward-related effects apart from the reward responsivity effects already observed. OBJECTIVE: The objective of this study was to determine whether or not nicotine withdrawal results in slower improvements in performance on a card-sorting task over a series of trials. METHOD: We carried out two experiments using a modified version of the CARROT, the mCARROT, to compare the performance of human participants in nicotine withdrawal with those who were satiated. RESULTS: Although withdrawal produced no direct effect on the mCARROT measure of reward responsivity, the overall sorting rate was lower, and the increase in sorting rate across successive trials was slower during nicotine withdrawal than during satiation. CONCLUSIONS: These data indicate that nicotine withdrawal impacted on task performance independently of the introduction of a performance contingent reward, suggesting a novel reward-related effect of nicotine withdrawal.

Recency and primacy in causal judgments: effects of probe question and context switch on latent inhibition and extinction.

Traditional associative models assume that associative weights are updated on a trial-by-trial basis. As a result, it is usually expected that responses based on these weights will tend to reflect the most recently presented contingencies. However, a number of studies of human causal judgments have shown primacy effects, wherein judgments obtained at the end of a series of trials are more strongly influenced by a contingency that was in force early in the sequence than by a contingency that was in force later in the sequence. The experiments described in this article replicated other work showing that requesting causal judgments during a sequence can reverse primacy and produce strong recency effects. Evidence was also obtained to suggest that primacy effects are produced by an interaction between latent inhibition and extinction processes and that requesting a judgment affects both of these processes.

Simulation of associative learning with the replaced elements model.

Associative learning theories can be categorized according to whether they treat the representation of stimulus compounds in an elemental or a configural manner. Since it is clear that a simple elemental approach to stimulus representation is inadequate, there have been several attempts to produce more elaborate elemental models. One recent approach, the replaced elements model (Wagner, 2003), reproduces many results that have until recently been uniquely predicted by Pearce's configural theory (Pearce, 1994). Although it is possible to simulate the replaced elements model using "standard" simulation programs, the generation of the correct stimulus representation is complex. The present article describes a method for simulation of the replaced elements model and presents the results of two example simulations that show differential predictions of replaced elements and Pearce's configural theory.

Dissociation of wanting and liking for alcohol in humans: a test of the incentive-sensitisation theory.

RATIONALE: Incentive sensitisation theory (IST) claims that the mechanism of reward is comprised of separate neurobiological systems of wanting and liking, that dependent drug use occurs as a result of sensitisation of the system controlling wanting, and that the two systems can be dissociated. OBJECTIVE: To test the IST prediction that wanting and liking for alcohol can be dissociated in humans. METHODS: Measures of wanting and liking for alcohol were obtained in three experiments. Experiment 1 examined whether liking for alcohol was associated with levels of wanting, as indexed by self-reported weekly alcohol intake. Experiments 2 and 3 also assessed the association between liking and wanting but in these experiments wanting was also indexed by alcohol consumption in the laboratory. Experiment 2 increased wanting for alcohol using an alcohol priming dose to determine whether liking would be similarly affected. Experiment 3 reduced liking for alcohol by adulterating drinks with Tween to see whether wanting would also be reduced. RESULTS: Little evidence for an association between liking and wanting for alcohol was found in Experiments 1-3 but, collapsing across all experiments, a weak positive correlation between liking and wanting was found. However, in Experiment 2, wanting was increased by the alcohol priming dose whereas liking was not and in Experiment 3 liking was reduced without a concurrent reduction in wanting. CONCLUSIONS: Although correlations between wanting and liking can be observed these results support the contention of the IST that wanting and liking for alcohol can be dissociated in human participants.

Asymmetry of generalization decrement in causal learning.

Two experiments required volunteers to learn which of various "planes" caused high levels of pollution. Novel test items were then rated as causes of pollution. Items created by adding novel features were rated at the same level as that of the original training items but items created by removing features received reduced ratings. This asymmetry of generalization decrement was not predicted by a well-known configural model of stimulus representation (Pearce, 1987, 1994) but was predicted by a recently proposed model of stimulus representation, the replaced-elements model (Brandon, Vogel, & Wagner, 2000).

Measures and models of nicotine dependence: positive reinforcement.

This paper addresses the problem of assessing nicotine dependence. The main objective is to develop theory-led suggestions for measures that will be relevant in the early phases of tobacco use, as well as in established smokers. Theoretical models of addiction falling into the general class of 'positive reinforcement theories' were identified and reviewed. From this review a number of drug effects and patterns of behaviour were distilled and categorized as either vulnerability or dependence indicators. A comparison of those features with the International Classification of Diseases (ICD-10) and Diagnostic and Statistical Manual (DSM-IV) diagnostic systems shows that neither system includes detailed assessment of vulnerability indicators. It is argued that measurement of vulnerability indicators, in addition to dependence indicators, may add to the predictive validity of assessments carried out in early career tobacco users, especially where there is limited evidence of established dependence. In addition, it is suggested that examination of measures that differentiate a subgroup of early career smokers termed 'rapid accelerators' may prove profitable and enable identification of the key parameters of nicotine reinforcement.

Outcome and cue properties modulate blocking.

Participants saw a series of situations in which a cue (a light appearing at a certain position) could be followed by an outcome (a drawing of a tank that exploded) and were afterwards asked to rate the likelihood of the outcome in the presence of the cue. In Experiments 1 and 2, the compound cues AT and KL were always followed by the outcome (AT+, KL+). During an elemental phase that either preceded or followed the compound phase, Cue A was also paired with the outcome (A+). Cue T elicited a lower rating than Cues K and L when cues were described as being weapons but not when the cues were said to be indicators. The magnitude of this blocking effect was also influenced by whether the outcome occurred to a maximal or submaximal extent. Experiment 3 replicated the effect of cue instructions on blocking (A+, AT+) but showed that cue instructions had no impact on reduced overshadowing (B-, BT+). The results shed new light on previous findings and support probabilistic contrast models of human contingency judgements.

Spatial separation of target and competitor cues enhances blocking of human causality judgements.

Three experiments were carried out. Each required subjects to make judgements about the causal status of cues following a two-stage blocking procedure. In Stage 1 a competitor cue was consistently paired with an outcome, and in Stage 2 the competitor continued to be paired with the outcome but was accompanied by a target cue. It was predicted that causal judgements for the target would be reduced by the presence of the competitor. In Experiments 1 and 2 the blocking procedure was implemented as a computer simulation of a card game during which subjects had to learn which cards produced the best payouts. The cues that subjects used to make their judgement were colours and symbols that appeared on the backs of the cards. When the target and competitor cues appeared on the same card blocking effects did not emerge, but when they appeared as part of different cards blocking effects were found. Thus, spatial separation of target and competitor cues appeared to facilitate blocking. Experiment 3 replicated the blocking result using spatially separated target and competitor cues.