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Biomedical subjects

P F Lovibond

Publications and source records attributed to P F Lovibond.

At least 19 recordsLinked to original sources
PubMed2000

Protection from extinction in human fear conditioning.

Two experiments examined the ability of an added stimulus to interfere with extinction of a target excitatory fear stimulus (a predictor of shock) in human autonomic conditioning. Both experiments demonstrated disruption of extinction when the added stimulus was inhibitory (a predictor of no shock, or safety signal). Subjects showed a return of fear when the target stimulus was tested alone, on both self-reported shock expectancy and skin conductance measures. The second experiment also demonstrated disruption of extinction when the added stimulus was excitatory. This results suggests that protection from extinction may occur even when the added stimulus is not inhibitory. Additional factors that may contribute to protection from extinction include context-specificity, occasion-setting and external inhibition. The results highlight the role that concurrent stimuli play in extinction, and emphasise the need to keep concurrent stimuli as similar as possible to the desired transfer context in practical applications of extinction such as exposure therapy for anxiety.

Adolescent↗
PubMed1998

Long-term stability of depression, anxiety, and stress syndromes.

At Time 1, 3,540 participants completed the Depression Anxiety Stress Scales (DASS). At Time 2, 3 to 8 years later, the DASS was readministered to 882 of these participants. There was strong evidence for selective stability of the syndromes of depression, anxiety, and stress. Each Time 2 scale was best predicted by the same scale at Time 1, with no significant increase in prediction from the other 2 Time 1 scales. Stability of the 3 syndromes did not vary systematically over the intervals studied. The results support the longitudinal stability of depression, anxiety, and stress and, in particular, draw attention to the distinction between anxiety symptoms and tension-stress symptoms. The results were interpreted as supporting the existence of syndrome-specific vulnerabilities, over and above a primary general vulnerability to emotional distress.

Adolescent↗
PubMed1998

Cue reactivity in dependent amphetamine users: can monistic conditioning theories advance our understanding of reactivity?

Forty-eight dependent injecting amphetamine users (AUs) and 48 controls were exposed to an amphetamine-related video and three affective control videos, and their amphetamine-related responses (amphetamine symptoms, withdrawal symptoms, and for AUs, "positive" and "negative" craving, based on the desire for positive and negative reinforcement, respectively) were recorded after each one. Both groups responded to the amphetamine video with increased withdrawal symptoms relative to control videos, suggesting that drug-related cues have significant unconditioned aversive properties. Between-group differences in amphetamine symptoms were evident only after the amphetamine video, supporting a conditioned drug agonistic model of cue reactivity. Among AUs, both positive and negative craving increased significantly after the amphetamine video, providing prima facie evidence for both conditioned withdrawal and conditioned drug agonistic accounts of cue reactivity. However, the lack of consistent and strong correlations between the two types of craving and the affective states hypothesized to induce such craving cannot be accommodated by the dominant models of the role of conditioning in maintaining addictive behaviours. This suggests a need to build upon theories of cue reactivity which predict conditioned responses to be either drug-like or drug-opposite.

Journal Article↗
PubMed1996

Expectancy bias in trait anxiety.

The ability of anxious and control participants to learn about signals for danger and safety was tested within an autonomic conditioned inhibition (A+/AB-) procedure. Only participants who could verbalize the differential contingencies between the stimuli and shock (aware participants) showed discrimination on electrodermal and shock expectancy measures. In Experiment 1, aware high-anxious participants showed similar responding to control participants. However unaware high-anxious participants showed heightened shock expectancy to all stimuli. Experiment 2 replicated this expectancy bias in anxious unaware participants controlling for shock intensity. In both experiments, expectancy bias was associated primarily with anxiety rather than depression. Results support the notion of an interpretive bias in anxious participants under ambiguous threat, consistent with recent findings from information-processing research on linguistic stimuli.

Adult↗
PubMed1996

Conditioning with facial expressions of emotion: effects of CS sex and age.

Two experiments examined the effects of facial expressions of emotion as conditioned stimuli (CSs) on human electrodermal conditioning and on a continuous measure of expectancy of the shock unconditioned stimulus. In Experiment 1, the CS+ was a picture of a person displaying an angry face and CS- was a neutral face. For half of the subjects, the expressions were depicted by males, for the other half by females. Male subjects showed larger skin conductance responses to pictures of males than did females. The responding of female subjects was the same regardless of the sex of the person in the picture. In Experiment 2, the CS+ and CS- were pictures of an angry or a happy face. For half of the subjects, the expressions were depicted by adult males, for the other half by preadolescent males. Subjects displayed greater differentiation when an adult male depicting anger was employed as the CS+ than when a preadolescent male depicting anger was the CS+. There were no differences when an adult or a child displayed happiness.

Adolescent↗
PubMed1995

The structure of negative emotional states: comparison of the Depression Anxiety Stress Scales (DASS) with the Beck Depression and Anxiety Inventories.

The psychometric properties of the Depression Anxiety Stress Scales (DASS) were evaluated in a normal sample of N = 717 who were also administered the Beck Depression Inventory (BDI) and the Beck Anxiety Inventory (BAI). The DASS was shown to possess satisfactory psychometric properties, and the factor structure was substantiated both by exploratory and confirmatory factor analysis. In comparison to the BDI and BAI, the DASS scales showed greater separation in factor loadings. The DASS Anxiety scale correlated 0.81 with the BAI, and the DASS Depression scale correlated 0.74 with the BDI. Factor analyses suggested that the BDI differs from the DASS Depression scale primarily in that the BDI includes items such as weight loss, insomnia, somatic preoccupation and irritability, which fail to discriminate between depression and other affective states. The factor structure of the combined BDI and BAI items was virtually identical to that reported by Beck for a sample of diagnosed depressed and anxious patients, supporting the view that these clinical states are more severe expressions of the same states that may be discerned in normals. Implications of the results for the conceptualisation of depression, anxiety and tension/stress are considered, and the utility of the DASS scales in discriminating between these constructs is discussed.

Adult↗
PubMed1995

Blocking in human electrodermal conditioning.

Associative blocking in human conditioning was investigated using electrodermal and self-reported US expectancy measures. Previous null results using a design reported by Lovibond, Siddle, and Bond (1988) suggested that a clearly demarcated phase structure and visual cues with semantic content may have distracted attention from the experimental contingencies. Therefore the current experiment intermixed pre-training and compound training trials and masked the transition to the test phase to remove or reduce phase boundaries. Simple coloured squares were used as CSs to reduce semantic content. A significant blocking effect was observed on both the expectancy measure and on the electrodermal measure. Both results were due to improved transfer of conditioning to the target CS in the overshadowing control group in comparison to previous experiments. The results were interpreted as providing evidence that previous null results were due to failure of transfer of learning across clearly distinct phases. There was no evidence of a dissociation between the electrodermal and self-report measures. Theoretical and procedural implications for human Pavlovian conditioning are discussed.

Adolescent↗
PubMed1993

The representation of feared outcomes.

A list of negative outcomes (harmful events) was constructed to investigate the nature and organization of outcome concerns in anxiety. In Study 1, analysis of worry frequency ratings for the 116 negative outcomes revealed two major correlated factors corresponding to physical outcomes (harm or misfortune) and social outcomes (negative evaluation). These higher-order factors could be further subdivided into smaller discrete categories of related concerns. Ratings of worry frequency were higher for social outcomes. Trait anxiety was associated with both physical and social concerns, but stress and depression were primarily associated with social concerns. In Study 2, aversiveness ratings for the 116 negative outcomes followed the same physical-social organization and formed similar lower-order categories. Unlike the worry frequency ratings, aversiveness ratings were higher for physical than social categories, and did not correlate substantially with trait measures of depression, anxiety or stress. In Study 3, a short (24-item) negative outcome questionnaire was developed to discriminate between concerns about physical and social outcomes. The Physical Scale correlated substantially with the Anxiety Sensitivity Index (ASI) but not the Fear of Negative Evaluation (FNE), whereas the Social Scale correlated with the FNE but not the ASI. The Penn State Worry Questionnaire (PSWQ), which assesses worry frequency but not content, correlated only with the Social Scale. Implications for theories of normal and clinical anxiety are discussed.

Adult↗
PubMed1993

Resistance to extinction of fear-relevant stimuli: preparedness or selective sensitization?

Human conditioning research has revealed an apparent resistance to extinction of aversive conditioning to pictures of fear-relevant stimuli such as snakes and spiders, supporting M. E. P. Seligman's (1971) preparedness theory of fears and phobias. This article examines an alternative account based on activation of preexisting response tendencies under threat (selective sensitization). Two experiments demonstrate that selective sensitization of electrodermal responses is attenuated when a fear-relevant stimulus serves as a negative conditioned stimulus (CS-), but is maintained when it serves as a positive conditioned stimulus (CS+). Previous extinction results may therefore be due to preservation of initial responding to CS+ but not CS-. Selective sensitization offers a model for the nonassociative activation of fears and phobias to prepotent stimuli under conditions of stress or threat. Possible genetic and cognitive mechanisms are discussed.

Acoustic Stimulation↗
PubMed1992

Tonic and phasic electrodermal measures of human aversive conditioning with long duration stimuli.

Two experiments investigated phasic and tonic electrodermal responding to long, variable-duration stimuli in aversive conditioning procedures. Experiment I demonstrated reliable differential conditioning on both phasic (first interval response, FIR) and tonic (change in skin conductance level, delta SCL; spontaneous fluctuations) measures, using 10-40-s slides as conditioned stimuli (CSs) and electric shock as the unconditioned stimulus (UCS). Experiment 2 examined the sensitivity of phasic and tonic measures to UCS aversiveness. Both FIR and delta SCL were greater to a conditioned stimulus paired with shock than one paired with an innocuous reaction-time warning tone. Responding was reversed when the reinforcement contingencies were reversed. It was suggested that, with long duration CSs and an aversive UCS, phasic measures to stimulus onset, such as FIR, may reflect both stimulus significance and threat appraisal, whereas tonic measures reflect primarily arousal or anxiety arising from anticipation of the aversive unconditioned stimulus.

Adult↗
PubMed1989

Effects of fear-relevance on electrodermal safety signal learning.

Safety signal learning in human subjects was investigated using a conditioned inhibition procedure with a shock unconditioned stimulus (US). The conditioned stimulus (CS) duration, and thus the CS-US interval, varied randomly from 20 to 50 s. Conditioning was assessed by change in tonic skin conductance level (SCL). Experiment 1 demonstrated reliable learning of a conditioned inhibition (A+/AB-) discrimination, in terms of both self-reported shock expectancy and change in SCL, in subjects who were able to report correctly the stimulus contingency. There was, however, no evidence of transfer of inhibitory properties from the safety signal B to a separately trained excitor. Experiment 2 compared two groups in which the safety signal was either fear-relevant (picture of snake or spider) or fear-irrelevant (flower or mushroom). As in previous research, there was no effect of fear-relevance on safety-signal learning. The results are discussed in terms of preparedness theory and excitatory conditioning with fear-relevant stimuli.

Cognition↗
PubMed1988

Predictive validity in human causal judgement and Pavlovian conditioning.

This paper first reviews the research on predictive validity in animal conditioning, and the informational theories deriving from this research. The major section of the paper examines the role of predictive validity, and thus the applicability of informational theories, in two major human learning paradigms: causal judgement and Pavlovian conditioning. There is more empirical support for informational theories in the causal judgement literature than in the conditioning literature. It is argued that judgement of predictive or causal relationships in humans is governed by processes similar to those governing conditioning in animals, and that the question of whether the same processes operate in human conditioning has not yet been adequately tested. Such a test would require joint measurement of predictive judgements and conditioned responding in a design which manipulates predictive validity independently of contiguity; it may also require a task which explicitly or implicitly restricts predictive judgements to the experimentally designated stimuli.

Animals↗
PubMed1985

Development of hypoglycemia and hyperglycemia as a function of number of trials in insulin conditioning.

A neutral environment paired with insulin injections can develop the capacity to elicit glycemic changes. However, both conditioned hypoglycemia and conditioned hyperglycemia have been reported under apparently similar circumstances. The present study examined conditioned glycemic changes as a function of the number of conditioning trials and the novelty of the conditioning environment. Adult, male Wistar rats were injected with either insulin or physiological saline every second day, in either a novel or a familiar environment. On the test day, all rats were injected with saline and blood was collected 20 minutes later for determination of glucose levels. In rats given insulin in the novel environment, conditioned hypoglycemia was observed after two trials but was replaced by conditioned hyperglycemia after five trials. No conditioning at all occurred in the familiar environment. The two conditioned responses observed were interpreted as reflecting two unconditioned responses brought about by insulin--a hypoglycemic response to the central detection of insulin, and a hyperglycemic response to the detection of (insulin-induced) hypoglycemia. Taken in conjunction with previous experiments in which both conditioned response patterns have occurred, the present results suggest that the homeostatic response of hyperglycemia can become strong enough to overcome the initial conditioned response of hypoglycemia, but that its establishment depends on the use of a novel conditioned stimulus and a larger number of conditioning trials.

Animals↗
PubMed1983

Facilitation of instrumental behavior by a Pavlovian appetitive conditioned stimulus.

Three experiments examined appetitive Pavlovian-instrumental interactions by presenting separately trained conditioned stimuli (CSs) during reinforced instrumental responding in rabbits. Intra-oral reinforcement was used to minimize interference from peripheral responses such as magazine approach. In experiment 1, the rabbits were first trained to perform an instrumental head-raising response for sucrose reward. A conditioned jaw movement response was then established to a 2-sec CS by pairing it with sucrose; a control stimulus was unpaired with sucrose. Instrumental responding maintained by a variable-interval 40-sec schedule was enhanced during 10-sec presentations of the paired, but not the unpaired, CS. Responding on a variable-ratio 15 schedule was unaffected except on trials on which the pre-CS baseline response rate was low; in such cases the paired CS caused a long-lasting acceleration of responding. Noncontingent presentation of the sucrose reinforcer itself briefly suppressed responding but had no long-term effect. In Experiment 2, a CS that had been conditioned at a 10-sec duration produced the same pattern of effects as in the first study, indicating that facilitation resulted from CS presentation rather than from the frustrative effects of non-reinforcement of the CS. In Experiment 3 an inhibitory CS blocked facilitation by the excitatory CS but did not itself affect instrumental responding. These results support the view that Pavlovian processes play a positive role in instrumental performance and suggest that previous findings of suppression by a short-duration CS reflect peripheral interference. The dependence of facilitation on the baseline level of responding is discussed in terms of associative and motivational theories of Pavlovian mediation.

Animals↗