Classical conditioning without verbal suggestions elicits placebo analgesia and nocebo hyperalgesia

The aim of this study was to examine the relationships among classical conditioning, expectancy, and fear in placebo analgesia and nocebo hyperalgesia. A total of 42 healthy volunteers were randomly assigned to three groups: placebo, nocebo, and control. They received 96 electrical stimuli, preceded by either orange or blue lights. A hidden conditioning procedure, in which participants were not informed about the meaning of coloured lights, was performed in the placebo and nocebo groups. Light of one colour was paired with pain stimuli of moderate intensity (control stimuli), and light of the other colour was paired with either nonpainful stimuli (in the placebo group) or painful stimuli of high intensity (in the nocebo group). In the control group, both colour lights were followed by control stimuli of moderate intensity without any conditioning procedure. Participants rated pain intensity, expectancy of pain intensity, and fear. In the testing phase, when both of the coloured lights were followed by identical moderate pain stimuli, we found a significant analgesic effect in the placebo group, and a significant hyperalgesic effect in the nocebo group. Neither expectancy nor fear ratings predicted placebo analgesia or nocebo hyperalgesia. It appears that a hidden conditioning procedure, without any explicit verbal suggestions, elicits placebo and nocebo effects, however we found no evidence that these effects are predicted by either expectancy or fear. These results suggest that classical conditioning may be a distinct mechanism for placebo and nocebo effects

Are profession and socioeconomic status important in social discounting?

Dyskontowanie jest definiowane jako spadek subiektywnej wartości nagród i kar. Czynników obniżających wartość nagrody jest wiele: m.in. czas oczekiwania na nagrodę, stopień pewności odnośnie do jej wystąpienia, liczba osób, z którymi należy podzielić się nagrodą oraz wysiłek, jaki należy włożyć w jej uzyskanie. W dyskontowaniu społecznym czynnikiem dyskontującym jest liczba osób, z którymi należy podzielić się nagrodą. Celem badania było określenie, czy skłonność do dzielenia się z obcymi ludźmi różni się u osób o odmiennym poziomie zasobności, jak również chciano określić, czy istnieją różnice w tempie dyskontowania społecznego u osób pracujących w różnych zawodach. W przeprowadzonym badaniu porównywano więc tempo dyskontowani społecznego u osób pracujących w służbie zdrowia (lekarzy specjalistów i stażystów) z tempem dyskontowania społecznego nauczycieli o różnym poziomie awansu zawodowego. Hipoteza dotycząca wolniejszego tempa dyskontowania osób o niższym statusie socjoekonomicznym nie została potwierdzona – uzyskano wyniki przeciwne do założeń. Pozostałe rezultaty obrazują trend, polegający na tym, że osoby o wyższym statusie socjoekonomicznym i jednocześnie z wieloletnią praktyką lekarską, charakteryzują się wolniejszym tempem dyskontowania.A human social discount function measures the value to a person of a reward to another person at a given social distance. People more willingly share their goods with members of family than strangers. Author decided to find a factor which is responsible for making decision of sharing with anyone. It is assumed that people working in certain professions like medical one are more eager to share with others. Also people with worse socioeconomic status probably want to share more willingly. They do not have anything to lose, so making decision is easier. In conducted research author wanted to check if there are differences in social discounting between people working in different professions and those who have differential socioeconomic status. The results of studies shows that people with higher socioeconomic status more willingly share. What is more, it is observed trend to statistical significance for variable profession

Rate of social discounting, income and proffession

Dyskontowanie to spadek subiektywnej wartości nagród i kar. W dyskontowaniu społecznym subiektywna wartość nagrody maleje wraz ze wzrostem liczby osób, z którymi należy się nią podzielić. Celem badania było określenie, czy tempo dyskontowania społecznego różni się u osób o odmiennym poziomie dochodu oraz u osób wykonujących zawody medyczne i niemedyczne. W przeprowadzonym badaniu porównywano tempo dyskontowania społecznego w czterech grupach: lekarzy specjalistów i stażystów oraz nauczycieli dyplomowanych i nauczycieli stażystów. Stwierdzono, że osoby o wyższych dochodach (lekarze specjaliści i nauczyciele dyplomowani) charakteryzuje istotnie wolniejsze tempo dyskontowania społecznego niż badanych o niższych dochodach (lekarze i nauczyciele stażyści). Zaobserwowano także trend, zgodnie z którym osoby wykonujące zawody medyczne (lekarze specjaliści i stażyści) dyskontują wolniej niż badani niebędący medykami (nauczyciele dyplomowani i stażyści)

How classical conditioning shapes placebo analgesia : hidden versus open conditioning

Objective: To investigate the influence of expectancy of pain intensity, fear of pain (trait), and fear (state) on the effectiveness of hidden and open conditioning to produce placebo analgesia. Methods: A total of 90 healthy female volunteers were randomly assigned to three groups (hidden conditioning, open conditioning, and control) that received electrical stimuli preceded by either orange or blue lights. One color was paired with painful stimuli (control stimuli) and the other color was paired with nonpainful stimuli (conditioned stimuli) in both the hidden and open conditioning groups. Only participants in the open conditioning group were informed about this association. In the control group, both color lights were followed by control stimuli. In the testing phase, both colored lights were followed by identical control stimuli. Participants rated pain intensity, expectancy of pain intensity, fear, and fear of pain. Results: A significant analgesic effect was found only in the hidden conditioning group, where no explicit verbal suggestions were provided. Hidden conditioning had an effect on expectancy and fear - participants in the hidden conditioning group expected less pain and experienced less fear in relation to conditioned stimuli. Fear was the only predictor of placebo analgesia in the hidden conditioning group. Neither expectancy of pain intensity nor fear of pain predicted placebo analgesia. Conclusions: Fear seems to be a more important factor than expectancy in producing placebo analgesia induced by hidden conditioning

The NRS results of repeated-measures analyses of variance (ANOVA) and planned comparisons.

<p>The NRS results of repeated-measures analyses of variance (ANOVA) and planned comparisons.</p

Reliability of measurement.

<p>Intraclass correlation coefficients for each of measured variables associated with condition stimuli (placebo, nocebo, control) or control stimuli.</p

Characteristics of the subjects in each experimental group.

<p>Characteristics of the subjects in each experimental group.</p

Mean differences (horizontal bars) in pain intensity, expectancy and fear during the testing phase of the study.

<p>Individual scores were plotted to show data distribution. In the testing phase, the differences in pain intensity in the placebo and nocebo groups were significantly higher than in the control group. * <i>p</i> < 0.01, ** <i>p</i> < 0.001.</p

Study design.

<p>A total of 42 female volunteers were randomly assigned to three groups: placebo, nocebo, and control group. Each group consisted of 14 participants. The study consisted of three phases: calibration, conditioning, and testing. Calibration was conducted to determine nonpainful tactile sensation (<i>t</i>) and the pain threshold (<i>T</i>). In the conditioning phase, a total of 72 electrical stimuli were delivered–half of the stimuli were of moderate intensity (1.5 × <i>T</i> mA, control stimuli) and the remaining half were nonpainful ([<i>t</i> + 0.8 × (<i>T—t</i>)] mA in placebo group) or higher intensity ([2.2 × <i>T</i>—0.2 × <i>t</i>] mA in nocebo group). The intensity of the electrical stimuli was always set at 1.5 × T mA in the control group. The testing phase consisted of 24 control stimuli (1.5 × T mA) regardless of group assignment.</p