## 3 Results
### Impairment of Right/Left Judgment  
FM patients have a longer reaction time (hands--20 images, t = 4.044, \(p<0.0001\), d = 1.04; hands--50 images t = 4.012, \(p<0.0001\), d = 1.31; feet--20 images t = 2.982, \(p<0.01\), d = 0.76; feet--50 images, t = 2.159, \(p<0.05\), d = 0.55) and lower accuracy for both hand and foot images (hands--20 images, t = \(-\)3.104, \(p<0.01\), d = 0.80; hands--50 images t = \(-\)3.455, \(p<0.01\), d = 0.89; feet--20 images t = \(-\)2.272, \(p<0.05\), d = 0.58; feet--50 images, t = \(-\)2.407, \(p<0.05\), d = 0.62). The Student's \(t\)-test showed statistical significance for all variables judging laterality with a moderate to high effect size; see Table 2.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Measures** & **FMS** & **Pain Free-Controls** & \(p\) **Value Independence** \\  & **(\(n\) = 30)** & **(\(n\) = 30)** & **Samples Student \(t\)-Test** \\ \hline Age & 52.43 \(\pm\) 11.28 & 47.93 \(\pm\) 5.92 & 0.68 \\ Pain (NPRS) & 6.23 \(\pm\) 1.99 & - & \\ FIQ & 88.04 \(\pm\) 3.71 & - & \\ \hline \hline \end{tabular}  
* Data are presented as mean (SD). Patients in the FMS sample present high intensities of clinical pain intensity on the numeric pain rating scale (NPRS), high levels of impact of the disease measured with the Fibromyalgia Impact Questionnaire (FIQ), lower tolerance to pressure pain threshold (PPT) and a dysfunction in the descending inhibitory capacity, as measured with conditioned pain modulation (CPM). Healthy subjects tolerate higher PTT and present good inhibitory system function. The FIQ and NPRS was administered only to FMS participants.  
\end{table}
Table 1: Descriptive statistics of demographic variables (\(n=60\)).  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Measures** & **FMS** & **Pain Free-Controls** & \(p\) **Value Samples** \\  & & & **Student \(t\)-Test** \\ \hline ACC hands & & & \\ (20 images) & 81.25 \(\pm\) 11.95 & 89.08 \(\pm\) 6.93 & 0.003 \\ ACC hands & & & \\ (50 images) & 81.63 \(\pm\) 7.98 & 88.26 \(\pm\) 6.84 & 0.001 \\ RT hands & & & \\ (20 images) & 2.79 \(\pm\) 0.95 & 2.01 \(\pm\) 0.45 & 0.000 \\ RT hands & & & \\ (50 images) & 3.02 \(\pm\) 0.81 & 2.35 \(\pm\) 0.43 & 0.000 \\ ACC feets & & & \\ (20 images) & 85.50 \(\pm\) 13.69 & 91.66 \(\pm\) 5.77 & 0.027 \\ ACC feets & & & \\ (50 images) & 84.03 \(\pm\) 9.50 & 89.13 \(\pm\) 6.65 & 0.001 \\ RT feets & & & \\ (20 images) & 2.54 \(\pm\) 1.05 & 1.94 \(\pm\) 0.34 & 0.004 \\ RT feets & & & \\ (50 images) & 2.63 \(\pm\) 0.90 & 2.23 \(\pm\) 0.46 & 0.035 \\ \hline \hline \end{tabular}  
* Group comparison of right/left judgment performance. ACC = accuracy in %, RT = reaction time in seconds, FM fibromyalgiaalgia. Results displayed as mean \(\pm\) SD.  
\end{table}
Table 2: Group comparison of right/left judgment performance between FM and pain free controls.  
The recording of the right/left laterality judgment task measurements counted the right/left recognition hit scores (% successes) and the reaction time required for the response. The successes rates for the feet and hand images when 20 of each were used with healthy volunteers were 89.08% and 91.66%, respectively (SD: 6.93% and 5.77%, respectively). However, in the group of fibromyalgia patients, the correct rate was slightly lower, i.e., 81.25% (SD: 11.95%) for the hands and 85.59% (SD: 13.69%) for 20 images of feet, with statistically significant differences for the two tasks (hands t = \(-\)3.104; \(p\) < 0.001; Feet: t = \(-\)2.272; \(p\) < 0.05).