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Placebo effects are important in pain reduction, but the effects are inconsistent. Prior experience with a pain stimulus may moderate placebo analgesia. The current study tests the effect of prior experience with a pain stimulus on placebo analgesia during a laboratory pain task. Healthy normotensive undergraduates (66 women, 68 men) who either did or did not report prior experience with pain from submerging a limb in cold water were enrolled. In the laboratory, an experimenter applied an inert, medicinal-smelling cream to participants' non-dominant hand. Participants randomized to the no-expectation group were told that the cream was a hand cleanser. Participants randomized to the placebo expectation group were told that the cream would reduce the pain associated with the cold pressor task. Participants then completed the cold pressor task and reported their pain on the short form of the McGill Pain Questionnaire. Analysis of variance revealed a main effect of expectation (p < .05), such that participants in the placebo expectation group reported less pain. An interaction was also found between expectation and prior experience (p < .05), such that participants with prior experience with pain from cold water immersion showed no difference in pain reports between expectation groups. In a pain context, prior experience with the pain stimulus may prevent a placebo expectation from reducing the experience of pain.

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Comparative optimism and dispositional optimism are typically studied separately and little is known regarding their unique and combined predictive abilities. We examined how these two types of optimism predict cognitive and affective reactions following unpleasant dental health feedback (Studies 1 and 2) and neutral feedback (Study 2). In Study 1, dispositional optimism and a measure of dental health comparative optimism interacted to predict appraisals of dental health feedback. In Study 2, dispositional optimism and dental health comparative optimism interacted to predict appraisals of new dental health information following negative dental health feedback - but not following neutral feedback. Individuals scoring high in dispositional optimism and low in dental health comparative optimism were more interested in and receptive to the dental health feedback than those scoring high in both types of optimism. Finally, greater dental health comparative optimism was associated with less negative affect following the dental health feedback, whereas dispositional optimism was associated with greater positive affect under all conditions. The results indicate that comparative and dispositional optimism are unique as well as interactive predictors.

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In a laboratory study we examined the hypothesis that placebo expectations enhance the initial identification of placebo-relevant sensations over placebo-irrelevant sensations. Participants (N = 102) were randomly assigned to one of three expectation groups. In the first group, participants ingested a placebo capsule and were told it was caffeine (deceptive expectation). In a second group, participants ingested a placebo capsule and were told it may be caffeine or it may be a placebo (double-blind expectation). Participants in the third group were given no expectation. All participants then tallied the placebo-relevant and placebo-irrelevant sensations they experienced during a 7-min period. Participants in the deceptive expectation group identified more placebo-relevant sensations than placebo-irrelevant sensations. No-expectation participants identified more placebo-irrelevant sensations than placebo-relevant sensations. Participants given the double-blind expectation identified an equal amount of placebo-relevant and irrelevant sensations. The amount of both placebo-relevant and placebo-irrelevant sensations detected mediated the relationship between the expectation manipulation and subsequent symptom reports. These data support the position that expectations cause placebo responding, in part, by altering how one identifies bodily sensations.

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UNLABELLED: Based on prior research identifying dispositional optimism as a predictor of placebo responding, the present study tested the hypothesis that individuals high in optimism would be more likely to respond to a placebo analgesic. Optimists and pessimists were randomly assigned to a placebo expectation condition or a no expectation condition before a cold pressor task. Blood pressure and heart rate were recorded before and during the cold pressor task, and participant ratings of pain and expectations were obtained immediately after the task. Analysis of the expectation manipulation revealed that the placebo instruction was successful in altering participant expectancy during the cold pressor. Supporting the main hypothesis, dispositional optimism was associated with lower pain ratings in the placebo condition but not in the control condition. Because dispositional optimism can alter placebo responding to laboratory pain, future studies should examine the potential role that this individual difference factor may play in patient responsivity to pharmacological and nonpharmacological treatments for clinical pain. PERSPECTIVE: This study examined the possibility that individual differences can predict placebo analgesia. Participants were randomly assigned to receive either a placebo expectation or no expectation before a cold pressor task. Dispositional optimism was related to less cold pressor pain in the placebo condition as compared with the control condition.

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It has been proposed that dispositional optimism is positively associated with treatment program engagement. However, conflicting evidence exists regarding this relationship. We examined whether the importance of a treatment goal moderates this association. In Study 1 (N = 95), individuals high in optimism were more interested in attending a nutrition education program when the importance of nutrition was first highlighted. In Study 2 (N = 91), participants were given the opportunity to attend psychotherapy to address an academic problem. Dispositional optimism was associated with greater treatment attendance when participants rated their problems as high, relative to low, in importance. It is concluded that the personality variable of dispositional optimism does relate to interest and attendance in treatment, however, treatment goal importance moderates these relationships. It is recommended that practitioners and researchers take an interactionist approach when assessing the role of personality and situational factors in treatment program interest and attendance.

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Research on generalized optimism has been primarily correlational in nature. The authors attempted to experimentally manipulate optimism separately from several related constructs (i.e., mood and self-esteem). They examined 2 different optimism manipulations. For the 1st one, participants generated thoughts about positive future events to induce an optimistic orientation. For the 2nd one, the authors exposed participants to an optimism-priming task. Both manipulations produced modest increases on a dispositional optimism measure and a situational optimism measure, compared with a control group. The momentary increases appeared particular to the optimism construct because the authors did not find similar increases on measures of mood and self-esteem. The authors provide preliminary evidence that generalized optimism can be validly and discriminantly manipulated.

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Research indicates that a positive relationship generally exists between dispositional optimism and goal engagement and attainment. The authors argue, however, that dispositional optimism may not always be associated with more active goal pursuit. Rather, they hypothesized that this relationship is moderated by how highly a goal is prioritized. For high-priority goals, they predicted that optimistic individuals would indeed increase goal engagement and would be more likely to attain their goal relative to individuals low in optimism. For low-priority goals, they anticipated that optimistic individuals would not display greater goal engagement or attainment. In 5 studies they assessed these predictions across a variety of domains, including friendship formation, exercise persistence, and scholastic achievement. Results supported their contention that goal priority acts as a moderator of the relationship between dispositional optimism and both goal engagement and goal attainment. Evidence of 1 mediator of this moderation effect-behavioral intentions-and of a limiting factor-the temporal ordering of goals-is also presented.

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Standing up against prejudice often requires one to surmount powerful inter- and intra-individual forces. Egalitarian standards alone are often insufficient to surmount these forces. As individuals high in dispositional optimism vigorously pursue valued goals, even when threatened with obstacles, we propose that the combination of high optimism and salient egalitarian goals predicts the confrontation of prejudice. In the present study, individuals high and low in both optimism and prejudice were randomly assigned to hear a racist joke followed by an argument, or to hear the same joke but without the argument. We found that low-prejudice optimists who had their chronic egalitarian values made salient by hearing the argument were highly likely to confront a later act of prejudice. Self-report data closely mirrored this behavioral finding. These findings support a self-regulatory approach to confrontation and suggest new avenues for combating prejudice.

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BACKGROUND: Prior studies with patient samples have found dispositional optimism to be associated with less pain. PURPOSE: We examined the relationship between optimism and experimental pain. It was hypothesized that optimists generally cope with a painful stimulus by mentally disengaging from the pain. However, if optimists are prompted to think about health and well-being prior to the painful event, they are more responsive to the pain. METHODS: Optimists and pessimists were primed with words related to health or with neutral words prior to the cold pressor task. Pain, distress, and cardiovascular reactivity to the cold pressor task were assessed. RESULTS: Dispositional optimism was associated with lower pain sensitivity, distress, and cardiovascular reactivity in the neutral prime condition. In the health prime condition, optimists and pessimists did not differ on any of the dependent measures. CONCLUSIONS: Dispositional optimism is associated with reduced pain for healthy adults encountering a brief pain stimulus. This relationship is eliminated, however, when individuals are primed with thoughts of health and well-being. The results are interpreted as evidence for the use of differential coping strategies by optimists in response to pain.

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OBJECTIVE: A prior investigation found that individuals low in optimism are more likely to follow a negative placebo (nocebo) expectation. The present study tested the hypothesis that individuals high in optimism are more likely to follow a positive placebo expectation. METHODS: Individuals (N=56) varying in their level of optimism were randomly assigned to one of three conditions. In the first condition, participants were given the expectation that a placebo sleep treatment would improve their sleep quality (placebo expectation condition). In the second condition, participants engaged in the same sleep treatment activity but were not given the positive placebo expectation (treatment control condition). Finally, a third group did not receive the positive placebo expectation and also did not engage in the placebo sleep treatment (no-placebo control condition). RESULTS: Optimism was positively associated with better sleep quality in the placebo expectation condition (r=.48, P<.05). Optimism scores were not associated with better sleep quality in either the treatment control condition (r=-.17, P=.46) or the no-placebo control condition (r=-.24, P=.35). CONCLUSION: Dispositional optimism relates to placebo responding. This relationship, however, is not manifested in a simple increase or decrease in all types of placebo responding. Rather, it appears that, as optimism increases, response to the positive placebo expectation increases, whereas response to nocebo expectation decreases. It is recommended that future research on personality and placebo effects consider the interaction between situational and dispositional variables.

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Conditioned taste aversions (CTAs) may be acquired when an animal consumes a novel taste (conditioned stimulus; CS) and then experiences the symptoms of poisoning (unconditioned stimulus; US). Animals will later avoid the taste that was previously associated with malaise. Extinction of a CTA is observed following repeated, non-reinforced exposures to the CS and represents itself as a resumption of eating/drinking the once-avoided tastant. Spontaneous recovery (SR) of a CTA (a revival of the taste avoidance) occurs when the CS is offered after a latency period in which the CS was not presented. An initial study explored the experimental parameters required to produce a reliable SR following acquisition and extinction of a robust CTA in rats. A CTA was formed through 3 pairings of 0.3% oral saccharin (SAC) and 81 mg/kg i.p. lithium chloride (LiCl) followed by extinction training resulting in 90% reacceptance of SAC. After extinction training, some of the animals were also tested for SR of the CTA upon exposure to SAC following a 15-, 30-, or 60-day latency period of water drinking. We report here that latencies of 15, 30, or 60 days produced small, but reliable, SRs of the CTA--with longer latencies producing progressively more suppression of SAC consumption. A second study investigated changes in the amygdala (AMY), gustatory neocortex (GNC), and medial prefrontal cortex (mPFC) functioning during SR of a CTA. Using immunohistochemical methods, brain c-Fos protein expression was analyzed in rats that extinguished the CTA as well as those that exhibited SR of the CTA after a 30-day latency. Our previous studies indicated that the numbers of c-Fos-labeled neurons in GNC and mPFC is low following CTA acquisition and increase dramatically as rats fully extinguished the aversion. Here we report that cortical c-Fos protein expression declines significantly following SR of the CTA. Expression of c-Fos in basolateral AMY decreased significantly from EXT to SR, but control animals with an intact CTA also decreased significantly from a short-term CTA test to a long-term CTA test. Low levels of c-Fos expression in the central nucleus of the amygdala (CE) were observed throughout EXT with little change in expression detectable following SR. These measurements reflect the dynamic nature of brain activity during acquisition and extinction of a CTA and highlight an important role for cortical neurons in the brain reorganization that occurs during SR of a CTA. The data also suggest that certain sub-nuclei of the AMY may play a relatively minor role in SR of this defensive reaction to a learned fear.

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This study used immunohistochemical methods to determine if the medial prefrontal cortex (mPFC) is involved in the extinction of a conditioned taste aversion (CTA). As rats reached 90% reacceptance of a tastant (saccharin: SAC) that had previously been associated with lithium chloride-induced malaise, c-Fos protein expression increased dramatically as compared to animals with active CTAs, animals without CTAs (i.e., explicitly unpaired CS-US exposures) or animals drinking SAC for the first time. These data indicate a role for mPFC (prelimbic and infralimbic cortex) in the formation of a CTA extinction memory.

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While substantial advances have been made in discovering how the brain learns and remembers, less is known about how the brain discards information, reorganizes information, or both. These topics are not only relevant to normal brain functioning but also speak to pathologies in which painful memories do not wane but are evoked time and again (e.g., post-traumatic stress disorder; PTSD). Here, we measured brain activity (as indicated by the regional expression of c-Fos protein) in rats during acquisition and throughout extinction of a conditioned taste aversion (CTA). We compared that brain activity with animals that had intact CTA memories or those that experienced an explicitly unpaired (EU) conditioned stimulus (CS; saccharin, SAC) and unconditioned stimulus (US; lithium chloride, LiCl). The data show a dynamic and nonuniform pattern of c-Fos protein expression in brain nuclei known to mediate gustation and CTAs. In particular, brainstem nuclei (e.g., nucleus of the solitary tract; NTS) and the basolateral nucleus of the amygdala (BLA) are active early as CTAs are formed and as extinction of the learned response begins. Later in the extinction process, the BLA reduces c-Fos expression relative to nonextinguished controls. Finally, as almost full reacceptance of the taste is achieved, the gustatory neocortex (GNC) expresses enhanced levels of c-Fos protein. Thus, extinction of a CTA is not represented by a simple reversal of the c-Fos activity evoked by CTA conditioning. Rather, the data demonstrate that extinction of conditioned responses is a dynamic process in which the activity levels of particular nuclei along the brain's taste pathway change depending on the extent to which the conditioned response has been extinguished.

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