Fig 1.
Experimental timeline procedure.
The procedure included two main phases: First, participants completed the baseline assessments, including psychological traits, emotional state, and two attentional bias tasks. Second, quantitative sensory testing was conducted alongside simultaneous ECG recording.
Fig 2.
Examples of trials in both loads of the Perceptual Load task.
A. Low load condition with a neutral picture trial; One target letter with a neutral distracting picture appearing at the center. B. High load condition with a pain picture trial; Four distracting letters with one target letter (the letter X) and a pain-related distracting picture appearing at the center.
Fig 3.
Example of a trial in the modified Dot probe task.
In this example, the probe appears in the location of the neutral word (i.e., pain-incongruent trial). ISI = Inter-Stimulus Interval.
Table 1.
Participant Demographics and Psychological Characteristics.
Table 2.
Mean and SD of pain intensity ratings on the 0-100 NPS along the one-minute test heat pain alone and under conditioning.
Fig 4.
Mean reaction times (RTs) in the Perceptual Load task as a function of load and picture valence.
RTs were generally slower under high perceptual load. Under low load, pain-related interfering images significantly slowed target identification compared to neutral images, whereas no such effect was observed under high load. Note: The RT scale is set from 400 to 1,200 ms to facilitate visualization of condition differences. Dots represent individual participants, the black line indicates the mean, and the shaded area represents the 95% confidence interval (CI). **p ≤ .01, ***p ≤ .001.
Table 3.
Descriptive statistics of HR and %HR during the test-stimulus given alone and during conditioning.
Fig 5.
HR at baseline, reactivity, and recovery during the test-stimulus alone (TS) and under conditioning (TS + CS).
HR was higher during the reactivity and recovery phases of the test-stimulus under conditioning compared to the corresponding phases of the test-stimulus alone. Moreover, HR during the recovery phase remained elevated relative to baseline in both conditions. Note: For clarity in visualizing differences between conditions, the HR scale is set from 55 to 125 bpm. Dots represent individual participants, the black line indicates the mean, and the shaded area represents the 95% confidence interval (CI). **p ≤ .01; HR = heart rate.
Table 4.
Block multiple linear regression analysis predicting pain-60 temperature.
Table 5.
Multiple linear regression analysis predicting CPM magnitude.
Table 6.
Multiple linear regression analysis predicting HR %change during CPM.
Fig 6.
Results of the exploratory analysis predicting HR reactivity (panel A) and recovery (panels B, C) from the CPM paradigm.
A. Higher levels of general distress predicted less change in HR during one-minute reactivity to the test-stimulus under conditioning. B. Higher attentional avoidance from pain-related words predicted elevated HR during recovery from the test-stimulus under conditioning. C. Interference from pain-related images under the low cognitive load of the Perceptual Load task predicted elevations in HR during recovery from the test-stimulus under conditioning. Note. CPM %HR change reactivity = the difference between HR during the test-stimulus under conditioning (CPM reactivity) and HR at baseline before the test, divided by the baseline HR; CPM %HR change at recovery = the difference between HR during the test-stimulus under conditioning (CPM reactivity) and during recovery, divided by the HR at reactivity. Dots represent individual participants, and the shaded area represents the 95% confidence interval (CI) *p < .05; **p < .01.
Table 7.
Multiple linear regression analysis predicting HR %change during recovery from CPM paradigm.