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Inverted Perceptual Judgment of Nociceptive Stimuli at Threshold Level following Inconsistent Cues.

Walter C, Dimova V, Bu J, Parnham MJ, Oertel BG, Lötsch J - PLoS ONE (2015)

Bottom Line: The random and often incorrect announcement of stimuli clearly below or above pain threshold caused the subjects to rate the stimuli at pain-threshold level in the opposite direction of the cue, i.e., when the stimuli were announced as "pain" significantly more often than as non-painful and vice versa (p < 10(-4)).The present study revealed the induction of associations incongruent with a given message in the perception of pain.These findings are consistent with reported data on the effects of distrust on non-painful cognitive responses.

View Article: PubMed Central - PubMed

Affiliation: Institute of Clinical Pharmacology, Goethe-University, Theodor-Stern-Kai 7, 60590, Frankfurt am Main, Germany.

ABSTRACT

Objective: The perception of pain is susceptible to modulation by psychological and contextual factors. It has been shown that subjects judge noxious stimuli as more painful in a respective suggestive context, which disappears when the modifying context is resolved. However, a context in which subjects judge the painfulness of a nociceptive stimulus in exactly the opposite direction to that of the cues has never been shown so far.

Methods: Nociceptive stimuli (300 ms intranasal gaseous CO2) at the individual pain threshold level were applied after a visual cue announcing the stimulus as either "no pain", merely a "stimulus", or "pain". Among the stimuli at threshold level, other CO2 stimuli that were clearly below or above pain threshold were randomly interspersed. These were announced beforehand in 12 subjects randomly with correct or incorrect cues, i.e., clearly painful or clearly non-painful stimuli were announced equally often as not painful or painful. By contrast, in a subsequent group of another 12 subjects, the stimuli were always announced correctly with respect to the evoked pain.

Results: The random and often incorrect announcement of stimuli clearly below or above pain threshold caused the subjects to rate the stimuli at pain-threshold level in the opposite direction of the cue, i.e., when the stimuli were announced as "pain" significantly more often than as non-painful and vice versa (p < 10(-4)). By contrast, in the absence of incongruence between announcement and perception of the far-from-threshold stimuli, stimuli at pain threshold were rated in the cued direction.

Conclusions: The present study revealed the induction of associations incongruent with a given message in the perception of pain. We created a context of unreliable cues whereby subjects perceived the stimulus opposite to that suggested by a prior cue, i.e., potentially nociceptive stimuli at pain threshold level that were announced as painful were judged as non-painful and vice versa. These findings are consistent with reported data on the effects of distrust on non-painful cognitive responses.

No MeSH data available.


Related in: MedlinePlus

Bar graph of the percentage of stimuli at threshold level that were perceived as painful, separately for each different cue and for the two groups.The columns and error bars indicate means and standard deviations. Left (red bars): In group 2, where among the stimuli at pain threshold level, correctly cued, far-from-threshold stimuli were randomly interspersed, a significantly higher percentage of stimuli at pain threshold level were rated as painful after a “pain” cue as compared to stimuli rated as painful after a “neutral” or a “no pain” cue. Right (blue bars, main results): In group 1, where, in contrast, the stimuli at threshold as well as the interspersed far-from-threshold stimuli were randomly and equally often cued as painful, neutral or not painful, s the effect was completely inversed. The group*cue interaction effect was statistically highly significant (Table 2). The dashed lines superimposed onto the bar graphs indicate the fits of the linear model used to mathematically describe the relationship between the percentages of stimuli at pain threshold level rated as painful and the three different cues as  (Table 4).
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pone.0132069.g002: Bar graph of the percentage of stimuli at threshold level that were perceived as painful, separately for each different cue and for the two groups.The columns and error bars indicate means and standard deviations. Left (red bars): In group 2, where among the stimuli at pain threshold level, correctly cued, far-from-threshold stimuli were randomly interspersed, a significantly higher percentage of stimuli at pain threshold level were rated as painful after a “pain” cue as compared to stimuli rated as painful after a “neutral” or a “no pain” cue. Right (blue bars, main results): In group 1, where, in contrast, the stimuli at threshold as well as the interspersed far-from-threshold stimuli were randomly and equally often cued as painful, neutral or not painful, s the effect was completely inversed. The group*cue interaction effect was statistically highly significant (Table 2). The dashed lines superimposed onto the bar graphs indicate the fits of the linear model used to mathematically describe the relationship between the percentages of stimuli at pain threshold level rated as painful and the three different cues as (Table 4).

Mentions: A different pattern of painful perception of the stimuli was observed for the stimuli at pain threshold level. In “group 1”, these stimuli were rated incongruently to the cues (Fig 2). That is, pain threshold CO2 stimuli were rated significantly less often as painful when pre-announced as painful than when cued neutrally or as not painful. Vice versa, pain threshold CO2 stimuli were rated significantly less often as non-painful when pre-announced as non-painful, than when cued neutrally or as painful (Table 2). This was not observed in the second group. That is, in “group 2”, prior announcement of the expected painfulness of the threshold CO2 stimuli resulted in the expected outcome (Fig 2). Stimuli at threshold level were rated significantly more often as painful when cued as such, than when pre-announced as being neutral or as no pain. This group difference among threshold stimuli judged as being either painful or not painful was statistically significant (rm-ANOVA interaction “group” by “cue”: F(2,44) = 24.03, p = 8.85 · 10-8; for further statistical details including mean values and standard deviations, see Table 2). According to the value of η2, the effect explained more than half of the total variance in the ratings of the stimuli as either painful or not (52.2%). The additional analysis of the certainty of the subjects about their judgement resulted in (i) subjects in the first group were less confident than those in the second group (between-subjects effect “group”: F(1,11) = 0.942, p = 0.011; for further statistical details including mean values and standard deviations, see Table 3) and (ii) all subjects were more confident when rating a stimulus as “not painful” (main effect “pain”: F(1,11) = 4.93, p = 0.048).


Inverted Perceptual Judgment of Nociceptive Stimuli at Threshold Level following Inconsistent Cues.

Walter C, Dimova V, Bu J, Parnham MJ, Oertel BG, Lötsch J - PLoS ONE (2015)

Bar graph of the percentage of stimuli at threshold level that were perceived as painful, separately for each different cue and for the two groups.The columns and error bars indicate means and standard deviations. Left (red bars): In group 2, where among the stimuli at pain threshold level, correctly cued, far-from-threshold stimuli were randomly interspersed, a significantly higher percentage of stimuli at pain threshold level were rated as painful after a “pain” cue as compared to stimuli rated as painful after a “neutral” or a “no pain” cue. Right (blue bars, main results): In group 1, where, in contrast, the stimuli at threshold as well as the interspersed far-from-threshold stimuli were randomly and equally often cued as painful, neutral or not painful, s the effect was completely inversed. The group*cue interaction effect was statistically highly significant (Table 2). The dashed lines superimposed onto the bar graphs indicate the fits of the linear model used to mathematically describe the relationship between the percentages of stimuli at pain threshold level rated as painful and the three different cues as  (Table 4).
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4493070&req=5

pone.0132069.g002: Bar graph of the percentage of stimuli at threshold level that were perceived as painful, separately for each different cue and for the two groups.The columns and error bars indicate means and standard deviations. Left (red bars): In group 2, where among the stimuli at pain threshold level, correctly cued, far-from-threshold stimuli were randomly interspersed, a significantly higher percentage of stimuli at pain threshold level were rated as painful after a “pain” cue as compared to stimuli rated as painful after a “neutral” or a “no pain” cue. Right (blue bars, main results): In group 1, where, in contrast, the stimuli at threshold as well as the interspersed far-from-threshold stimuli were randomly and equally often cued as painful, neutral or not painful, s the effect was completely inversed. The group*cue interaction effect was statistically highly significant (Table 2). The dashed lines superimposed onto the bar graphs indicate the fits of the linear model used to mathematically describe the relationship between the percentages of stimuli at pain threshold level rated as painful and the three different cues as (Table 4).
Mentions: A different pattern of painful perception of the stimuli was observed for the stimuli at pain threshold level. In “group 1”, these stimuli were rated incongruently to the cues (Fig 2). That is, pain threshold CO2 stimuli were rated significantly less often as painful when pre-announced as painful than when cued neutrally or as not painful. Vice versa, pain threshold CO2 stimuli were rated significantly less often as non-painful when pre-announced as non-painful, than when cued neutrally or as painful (Table 2). This was not observed in the second group. That is, in “group 2”, prior announcement of the expected painfulness of the threshold CO2 stimuli resulted in the expected outcome (Fig 2). Stimuli at threshold level were rated significantly more often as painful when cued as such, than when pre-announced as being neutral or as no pain. This group difference among threshold stimuli judged as being either painful or not painful was statistically significant (rm-ANOVA interaction “group” by “cue”: F(2,44) = 24.03, p = 8.85 · 10-8; for further statistical details including mean values and standard deviations, see Table 2). According to the value of η2, the effect explained more than half of the total variance in the ratings of the stimuli as either painful or not (52.2%). The additional analysis of the certainty of the subjects about their judgement resulted in (i) subjects in the first group were less confident than those in the second group (between-subjects effect “group”: F(1,11) = 0.942, p = 0.011; for further statistical details including mean values and standard deviations, see Table 3) and (ii) all subjects were more confident when rating a stimulus as “not painful” (main effect “pain”: F(1,11) = 4.93, p = 0.048).

Bottom Line: The random and often incorrect announcement of stimuli clearly below or above pain threshold caused the subjects to rate the stimuli at pain-threshold level in the opposite direction of the cue, i.e., when the stimuli were announced as "pain" significantly more often than as non-painful and vice versa (p < 10(-4)).The present study revealed the induction of associations incongruent with a given message in the perception of pain.These findings are consistent with reported data on the effects of distrust on non-painful cognitive responses.

View Article: PubMed Central - PubMed

Affiliation: Institute of Clinical Pharmacology, Goethe-University, Theodor-Stern-Kai 7, 60590, Frankfurt am Main, Germany.

ABSTRACT

Objective: The perception of pain is susceptible to modulation by psychological and contextual factors. It has been shown that subjects judge noxious stimuli as more painful in a respective suggestive context, which disappears when the modifying context is resolved. However, a context in which subjects judge the painfulness of a nociceptive stimulus in exactly the opposite direction to that of the cues has never been shown so far.

Methods: Nociceptive stimuli (300 ms intranasal gaseous CO2) at the individual pain threshold level were applied after a visual cue announcing the stimulus as either "no pain", merely a "stimulus", or "pain". Among the stimuli at threshold level, other CO2 stimuli that were clearly below or above pain threshold were randomly interspersed. These were announced beforehand in 12 subjects randomly with correct or incorrect cues, i.e., clearly painful or clearly non-painful stimuli were announced equally often as not painful or painful. By contrast, in a subsequent group of another 12 subjects, the stimuli were always announced correctly with respect to the evoked pain.

Results: The random and often incorrect announcement of stimuli clearly below or above pain threshold caused the subjects to rate the stimuli at pain-threshold level in the opposite direction of the cue, i.e., when the stimuli were announced as "pain" significantly more often than as non-painful and vice versa (p < 10(-4)). By contrast, in the absence of incongruence between announcement and perception of the far-from-threshold stimuli, stimuli at pain threshold were rated in the cued direction.

Conclusions: The present study revealed the induction of associations incongruent with a given message in the perception of pain. We created a context of unreliable cues whereby subjects perceived the stimulus opposite to that suggested by a prior cue, i.e., potentially nociceptive stimuli at pain threshold level that were announced as painful were judged as non-painful and vice versa. These findings are consistent with reported data on the effects of distrust on non-painful cognitive responses.

No MeSH data available.


Related in: MedlinePlus