Peter F. Lovibond’s research while affiliated with University of South Wales and other places

Can conditioning occur without conscious awareness of the contingency between the stimuli? We trained participants on two separate reaction time tasks that ensured attention to the experimental stimuli. The tasks were then interleaved to create a differential Pavlovian contingency between visual stimuli from one task and an airpuff stimulus from the other. Many participants were unaware of the contingency and failed to show differential eyeblink conditioning, despite attending to a salient stimulus that was contingently and contiguously related to the airpuff stimulus over many trials. Manipulation of awareness by verbal instruction dramatically increased awareness and differential eyeblink responding. These findings cast doubt on dual-system theories, which propose an automatic associative system independent of cognition, and provide strong evidence that cognitive processes associated with awareness play a causal role in learning.

Intolerance of Uncertainty (IU) has gained increasing interest as a vulnerability factor for worry in Generalized Anxiety Disorder and other emotional disorders. We extended the procedure of Grupe and Nitschke (2011) to compare threat processing in High IU (n=. 29) and Low IU (n=. 26) participants. Participants viewed four cues: two reference cues that preceded aversive pictures on 100% or 0% of trials, and a target cue that preceded aversive pictures on 50% of trials (Uncertain condition). Participants were instructed about these probabilities in advance. In addition, we surprised participants with a second target cue that also preceded aversive pictures on 50% of trials but that had not been mentioned in the instructions (Ambiguous condition). Results provided preliminary evidence that High IU participants showed greater online threat expectancy, postexperimental covariation estimates and negative mood for the target cues compared to the reference cues. The results also suggest that among high IU individuals, ambiguity, rather than uncertainty per se, may be a particularly powerful trigger for biased threat appraisal and negative affect. Clinically, the results suggest that patients with high IU may benefit from interventions to help them calibrate the degree of risk in situations involving ambiguous threat.

Reward-associated cues are thought to promote relapse after treatment of appetitive disorders such as drug-taking, binge eating, and gambling. This process has been modelled in the laboratory using a Pavlovian-instrumental transfer (PIT) design in which Pavlovian cues facilitate instrumental reward-directed action. Attempts to reduce facilitation by cue exposure (extinction) have produced mixed results. We tested the effect of extinction in a recently developed PIT procedure using a natural reward, chocolate, in human participants. Facilitation of instrumental responding was only observed in participants who were aware of the Pavlovian contingencies. Pavlovian extinction successfully reduced, but did not completely eliminate, expectancy of reward and facilitation of instrumental responding. The results indicate that exposure can reduce the ability of cues to promote reward-directed behavior in the laboratory. However, the residual potency of extinguished cues means that additional active strategies may be needed in clinical practice to train patients to resist the impact of these cues in their environment. Copyright © 2015. Published by Elsevier Ltd.

Generalization of conditioned fear has been implicated in the maintenance and proliferation of fear in anxiety disorders. The role of cognitive processes in generalization of conditioning is an important yet understudied issue. Vervliet et al. (2010) tested generalization of fear to a visual stimulus of a particular color and shape paired with electric shock. Test stimuli shared either the color or shape of the CS +. Prior to conditioning, participants were instructed that either color or shape would be predictive of shock. Generalization was stronger to the stimulus containing the instructed feature, suggesting that instructions impacted generalization of fear. However, the result may also reflect the impact of instructions on attention and learning during the conditioning phase. In the present study, the instructional manipulation was given after the conditioning phase to control for any impact of instructions on learning. A similar result to that reported by Vervliet et al. (2010) was observed. On self-reported expectancy of shock, generalization was greater to the test stimulus that included the instructed stimulus feature. The same pattern was observed on skin conductance, although it did not reach statistical significance. The findings indicate that explicitly instructed information affected generalization of conditioned fear independently of any impact on learning, pointing to the role of cognitive processes in human fear generalization. They also support the utility of cognitive therapy approaches, which are employed after fear has already developed, in addressing clinical overgeneralization.

Background and Objectives Excessive generalisation of fear learning has recently been implicated in the development and maintenance of anxiety disorders such as Posttraumatic Stress Disorder. Evidence is growing to suggest that cognitive processes such as rule-abstraction may be involved in fear generalization. In a study by Vervliet et al (2010), verbal instructions regarding the relevance of stimulus colour or shape for predicting the delivery of an electric shock led to greater generalisation of fear to novel stimuli which contained the instruction-relevant feature. Here, we examined the impact of pre-training rather than instructing feature relevance. Methods A pre-training phase was used to allow learning of the predictive relevance of either stimulus colour or shape. This was followed by the same conditioning and generalization phases used in the previous study. Results There was greater generalisation of fear to the test stimulus that contained the pre-training relevant feature (either colour or shape), and this effect was stronger in participants who correctly reported the training rule. This pattern was statistically significant on the expectancy measure but not on skin conductance. Limitations High levels of variability on the skin conductance measure reduced the power to detect a significant difference on test. Conclusions The results demonstrate the potential for prior experiences and the beliefs derived from them to impact on generalisation of fear. They also add to the evidence for an involvement of higher-order cognitive processes in how fear learning spreads and how such a process may be addressed clinically.

Learning may play an important role in over-eating. One example is Pavlovian-to-instrumental transfer (PIT), whereby reward cues facilitate responding to obtain that reward. While there is increasing research indicating PIT for food in humans, these studies have exclusively tested PIT under instrumental extinction (i.e. when the food is no longer available), which may reduce their ecological validity. To address this, we conducted two experiments exploring PIT for food in humans when tested under instrumental reinforcement. Participants first underwent Pavlovian discrimination training with an auditory cue paired with a chocolate reward (CS+) and another auditory cue unpaired (CS-). In instrumental training participants learnt to press a button to receive the chocolate reward on a VR10 schedule. In the test phase, each CS was presented while participants maintained the opportunity to press the button to receive chocolate. In Experiment 1, the PIT test was implemented after up to 20 min of instrumental training (satiation) whereas in Experiment 2 it was implemented after only 4 mins of instrumental training. In both experiments there was evidence for differential PIT, but the pattern differed according to the rate of responding at the time of the PIT test. In low baseline responders the CS+ facilitated both button press responding and consumption, whereas in high baseline responders the CS- suppressed responding. These findings suggest that both excitatory and inhibitory associations may be learnt during PIT training and that the expression of these associations depends on motivation levels at the time the cues are encountered. Particularly concerning is that a food-paired cue can elicit increased motivation and consumption of food even when the participant is highly satiated and no longer seeking food, as this may be one mechanism by which over-consumption is maintained.

Much of contemporary associative learning research is focused on understanding how and when the associative history of cues affects later learning about those cues. Very little work has investigated the effects of the associative history of outcomes on human learning. Three experiments extended the "learned irrelevance" paradigm from the animal conditioning literature to examine the influence of an outcome's prior predictability on subsequent learning of relationships between cues and that outcome. All 3 experiments found evidence for the idea that learning is biased by the prior predictability of the outcome. Previously predictable outcomes were readily associated with novel predictive cues, whereas previously unpredictable outcomes were more readily associated with novel nonpredictive cues. This finding highlights the importance of considering the associative history of outcomes, as well as cues, when interpreting multistage designs. Associative and cognitive explanations of this certainty matching effect are discussed. (PsycINFO Database Record (c) 2015 APA, all rights reserved).

Numerous studies indicate that placebo analgesia can be established via conditioning procedures. However, these studies have exclusively involved conditioning under continuous reinforcement. Thus, it is currently unknown whether placebo analgesia can be established under partial reinforcement and how durable any such effect would be. We tested this possibility using electro-cutaneous pain in healthy volunteers. Sixty undergraduates received placebo treatment (activation of a sham electrode) under the guise of an analgesic trial. The participants were randomly allocated to different conditioning schedules, namely continuous reinforcement (CRF), partial reinforcement (PRF), or control (no conditioning). Conditioning was achieved by surreptitiously reducing pain intensity during training when the placebo was activated compared with when it was inactive. For the CRF group, the placebo was always followed by a surreptitious reduction in pain during training. For the PRF group, the placebo was followed by a reduction in pain stimulation on 62.5% of trials only. In the test phase, pain stimulation was equivalent across placebo and no placebo trials. Both continuous and partial reinforcement produced placebo analgesia, with the magnitude of initial analgesia being larger following continuous reinforcement. However, while the placebo analgesia established under continuous reinforcement extinguished during test phase, the placebo analgesia established under partial reinforcement did not. These findings indicate that partial reinforcement can induce placebo analgesia and that these effects are more resistant to extinction than those established via continuous reinforcement. Partial reinforcement may, therefore, reflect a novel way of enhancing clinical outcomes via the placebo effect.

Evidence from both empirical studies and clinical practice indicates that substantial reductions in pain can be observed following placebo treatment. Generally, these effects are attributed to expectancy and/or classic conditioning. However, other psychological processes that could bias the observed responses to placebo treatment may lead to a systematic over- or underestimate of the magnitude of the placebo effect. First, demand characteristics could encourage participants or patients to respond in a way consistent with their perceptions of the study's or treatment's aims. Second, knowledge of being in a study, or receiving treatment, could lead to changes in behavior and reporting as a result of the Hawthorne effect. Third, response shift may invalidate pre-post intervention comparisons if the criteria for evaluating the relevant symptom change as a result of the intervention. This chapter reviews evidence for these three processes as they relate to placebo effects for pain.