Effects of Feedback Control on Slow Cortical Potentials and Random Events

As known for more than two decades, humans can learn to achieve self-control over their brain activity such as the polarity of slow cortical potential (SCP) shifts referred to as positivity or negativity. This learning process is supported by the visual feedback of the SCP in a time-locked trial structure. On the other hand, it has been repeatedly shown that humans are able to regulate the random distribution of events, produced by an electronic random event generator (REG) as a psychokinetic effect. This procedure also entails feedback of the distribution of binary random events to the subject; however, contrary to the feedback of SCP, there is no known physical connection from the subject to REG. In both cases, the to-be-controlled function should be changed in one of two alternative directions (“bi-directional control”) by use of two different cognitive strategies or states of consciousness. In the present experiment the effect of a self-chosen strategy was examined for the regulation of a feedback signal in a pseudorandomized predefined direction both on the SCP and the REG. Therefore, the system, called “Thought Translation Device” (TTD) provided feedback of the SCP or the REG. This modality was changed every block of 300-400 trials of 4.5 to 5s duration each. The task requirement was assigned pseudorandomly. A correctly produced SCP or REG shift was rewarded with a smily face. The simultaneous recording of the Electroencephalogram (EEG) and the REG signal allowed investigating psychophysiological correlates of psychokinetic effects. This study focused on the differentiation between the two tasks of the REG or SCP signal when feeding back one of them. Four subjects performed in total 3500 trials with SCP feedback and 3500 trials with feedback of the REG. The average feedback value of all trials was analyzed and tested for being different from a baseline value taken before the start of the feedback in each trial using a t-test. The previous findings that human subjects can self-regulate their SCP within the first sessions were replicated. Highly significant SCP control was achieved only by the highly motivated subjects (S 2+S 3) who attended in more than one day. S 2 attained a constant high correct response rate of 70 to 80 % during the second and third training day. It was also shown that a temporary “false feedback” given by the REG did not necessarily disturb the acquisition of SCP self-control. Task-specific lateralization of the SCP (which was not fed back) was not significant. The highly motivated subjects achieved higher t-values in the REG control than S 1 and S 4. When considering both feedback modes together, a significant correlation between pre-defined task requirement and the deviation from chance expectancy produced by the REG (p=0.02) was produced. This can be interpreted as a psychokinetic effect. The correlation between task and REG result produced by the system when running the same number of trials was far from significance. Feedback of SCP seemed not to disturb the positive correlation between task and REG. Despite these similarities between the behavior of the REG and the SCPs, the differentiation of the REG signal did not significantly correlate with SCP amplitudes or SCP lateralization.