26 February 2005

Effects of experimenter characteristics and men and woment's pain reports

More on one of my favorite topics:

The effects of experimenter characteristics on pain reports in women and men
Ibolya Kállai, et.al
In pain research, one important aspect of pain is its report, i.e. its verbal and behavioral indication towards others. As the report of pain virtually always takes place in the presence of another person, for example a physician or an experimenter, a close examination of the effect this person might have on the report of pain is paramount. In a clinical context, the pain report fulfils a function by communicating the problem to the physician thus facilitating diagnosis and therapy. In the absence of the necessity to deliver a vital message, as is the case in most experimental settings, the subject's pain report is likely influenced by additional parameters (Robinson and Wise, 2003).

Several studies suggest that traditional gender roles influence the verbalization of pain (Levine and De Simone, 1991, Robinson and Wise, 2003 and Sanford et al., 2002). Generally, gender role refers to a society's widely assumed set of characteristics for each sex and may comprise beliefs regarding appropriate pain behaviors. Whereas the stereotypical male role in Western society characterizes men as stoic and intending to impress women with their ability to withstand pain, the corresponding female role expects women to exhibit increased sensitivity in order to evoke protective behavior in men (Levine and De Simone, 1991). Some authors confirmed these expectations investigating the influence of the experimenters' gender in a cold pressor test (Carter et al., 2002, Levine and De Simone, 1991 and Voss, 2001), whereas others found no such effects (Otto and Dougher, 1985). Furthermore, women generally report higher pain levels than men (Fillingim and Maixner, 1995 and Riley et al., 1998).

Apart from gender effects, other characteristics of the experimenter might also influence pain reports. Considering the typical setting of psychological experiments, a factor varying across studies is whether the experiments are conducted by students or members of the faculty. Although it is questionable whether student experimenters obtain the same results as experimenters of a higher professional level, few reports mention the professional status of the experimenter. Student experimenters may be perceived as possessing lower authority or competence compared to faculty members, leading subjects to believe that experiments conducted by students may be less important and/or safe than those carried out by faculty members. If a subject doubts the importance of the experiment or the experimenter's competence, the subject may not give his/her best and may not be willing to endure much pain.

The current study investigates not only gender effects, but also the effect of the experimenter's professional status on the subjects’ pain responsivity. We expected that subjects tested by a professional experimenter would show higher pain thresholds and pain tolerance as well as lower pain intensity ratings compared to subjects who were tested by a student experimenter. Regarding gender, we anticipated female subjects to report pain earlier and to endure it for briefer time periods than male subjects. Further, both male and female subjects were expected to demonstrate higher pain thresholds, higher pain tolerance and lower pain intensity ratings when examined by female than by male experimenters.
4. Discussion

4.1. Experimenter professional status
As expected, there was a significant main effect on pain tolerance for experimenter professional status. Pain tolerance was significantly higher when subjects were tested by a professional experimenter compared to a student experimenter and more subjects were willing to endure the pain for the full 3 min. Interestingly, this effect was not seen for pain threshold or pain intensity. This suggests that the presence of the professional experimenter did not affect the perception or report of pain, but the will to endure it.

An explanation for this effect might be that the subjects tested by the professional experimenters were motivated more strongly and attributed more importance to the experiment. Further analyses showed that the professional experimenters were perceived as possessing significantly more authority than the student experimenters. This perception of authority may have underlined the importance of the experiment and given rise to more effort on the side of the subjects. Although the higher pain tolerance in the presence of a high professional experimenter could theoretically also be mediated by the perceived competence of the experimenter, leading to greater confidence that the experimental pain-inducing situation is handled with care, we could not find statistical evidence supporting such an interpretation. Further, this effect was not due to the fact that the professional experimenters were liked better than the student experimenters as the student experimenters were rated as significantly more likeable.

4.2. Gender effects
Analysing gender effects, we found an interaction between experimenter gender and subject gender for pain tolerance. As could be expected from the literature, men tolerated pain longer when tested by a female experimenter than by a male one (e.g. Levine and De Simone, 1991). However, contrary to our expectations, women also tolerated pain longer when tested by a male experimenter. According to traditional gender role assumptions (cf. Robinson and Wise, 2003 and Sanford et al., 2002), we assumed that women would show higher pain responsivity, for example lower pain tolerance, when tested by a male experimenter, in order to appear helpless and induce male protection. The interaction observed between experimenter gender and subject gender, however, indicates that it is not only men (as we expected) but also women who display increased pain tolerance when tested by a person of the opposite sex in order to impress this person. For women, this behavior—though gender role related—is not in accordance with the traditional gender role outlined above. One reason for this finding, which is unexpected in the light of previous literature, may be that the female gender roles are in flux at the present time, especially among the student population. A further possible explanation could be that there are cultural differences regarding gender roles that would explain the differences between our German sample and the American samples investigated in previous literature (c.f. Carter et al., 2002, Levine and De Simone, 1991 and Robinson and Wise, 2003). Again, the interaction observed between experimenter gender and subject gender was not found for pain threshold or pain intensity, indicating that the will to endure the pain was affected but not the report or the perception of the pain itself.

Furthermore, we found a significant effect for experimenter gender in pain intensity. Both men and women rated pain intensity higher when tested by female experimenters. This effect is contrary to our expectations, as we assumed that, in accordance with traditional gender roles, both men and women would report lower pain intensity to female experimenters than to male experimenters. One explanation for this unexpected result might be that the pain intensity ratings were collected following the cold pressor task and not while the subjects had their hands immersed in the ice-water. For example, in the case of male subjects, it could be the case that they would rate pain intensity as ‘low’ in front of female experimenters while they are actually experiencing the pain, thereby trying to impress the woman by saying that they do not feel much pain. However, when asked to rate pain intensity after the test has already ended, as was the case in our experiment, they might try to impress the female experimenters by saying that they were able to endure high pain intensities. This result warrants further research.

In our study, we did not find any main effect involving subject gender although, according to previous literature (cf. Riley et al., 1998), we expected that women would report higher pain levels and would be less willing to endure the pain compared to men. Generally, men and women did not differ significantly in their pain thresholds, pain tolerance or pain intensity ratings, even though the descriptive differences pointed in the expected direction.

In summary, our findings indicate that pain responsivity, i.e. the will to endure pain as well as the report of pain, might be influenced in part by the characteristics of the person to whom the pain is expressed. This finding may have consequences for pain research in general and for the interpretation of already existing studies. Inconsistent results of earlier studies should be re-examined with respect to experimenters’ attributes and the relation between experimenter and subject. Additionally, in clinical settings, it should always be remembered that attributes of physicians, therapists and other health-care professionals may have an influence on the pain levels expressed by the patients.

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