Modulation of the postural effects of cognitive load by hypnotizability

Abstract

Aim of the experiment was to study whether cognitive load affects postural control more in low (Lows) than in highly hypnotizable (Highs) subjects due to the latter's greater attentional abilities. Standing Highs and Lows underwent an experimental session (closed eyes) consisting of a basal condition and of mental computation in an easy (stable support) and a difficult (unstable support) postural condition. Variability [standard deviation (SD)] and complexity [sample entropy (SampEn)] of the movement of the centre of pressure (CoP), its mean velocity (Velocity), the area swept by the CoP (Area) and the ratio between the CoP trajectory length and area [length for surface (LFS)] were measured. Few hypnotizability-related differences were detected (reduction in the Highs' SD and increases in the Lows' LFS in the difficult postural condition). Thus, the hypnotizability-related postural differences observed in previous studies during sensory alteration could not be accounted mainly by attentional abilities.

Hypnotizability-Related Effects of Vestibular Impairment on Posture and Locomotion

“…Although significant group effects and interactions were not observed, in line with previous findings (Santarcangelo, Scattina, Carli, et al, 2008) the highs' sway area (Figure 1) tended to be larger than lows' sway area, F(1, 20) = 3.432, p = .079. This was more apparent during backward head extension on the unstable support, t(1, 20) = 2.020, p = .057.…”

“…More recently, the hypnotizability-related effects of the alteration of visual and leg/neck proprioceptive inputs on posture and locomotion have been studied. The results have shown that highs' center of pressure (CoP) exhibits larger and faster sway than lows' when vision is occluded and/or the leg proprioceptive input is altered, which was not due to a lower postural stability but to preeminently centrally driven control mechanisms allowing more loose adjustments of highs' body sway (Santarcangelo, Scattina, Carli, Macerata, & Manzoni, 2008). In addition, highs' CoP movement is less influenced than lows' by asymmetrical tonic alteration of the neck proprioceptive information due to prolonged head rotation .…”

“…On the basis of these findings, it was hypothesized that highs' motor control is characterized by a preeminent role of centrally driven commands depending on the individual internal reference system with respect to the peripheral sensory feedback (Santarcangelo, Scattina, Carli, et al, 2008;Menzocchi et al, 2010).…”

Is high hypnotizability a trouble in balance control?

“…Previous studies have shown that the diVerent attentional abilities of Highs and Lows (see Carli et al 2008a) were not responsible for the hypnotizability-related diVerences in body sway observed during easy postural tasks (Santarcangelo et al 2009), but higher attentional resources might have compensated lower abilities in sensori-motor integration and account for the similar performance of Highs and Lows during highly demanding postural tasks.…”

Review of Methods for the Evaluation of Human Body Balance

“…Related to Borg and Laxaback (2010) further research activities are necessary to identify the correct physiological interpretation of SE. SE was used in many studies of balance where different interpretations of it may be found (Cavanaugh, Mercer, & Stergiou, 2007;Deffeyes et al, 2009;Donker, Roerdink, Greven, & Beek, 2007;Duarte & Sternad, 2008;Haran & Keshner, 2008;Santarcangelo et al, 2009;Schmit, Regis, & Riley, 2005;Stins, Michielsen, Roerdink, & Beek, 2009). …”