Fig. 2

Measuring meta-volition with asynchronous choice. The relation between the probability of choosing the first target and the target asynchrony (δ) is a monotonically increasing function ranging from chance to 1. When δ is low the probability of choosing the first target is closer to chance (plot a) than when δ is high (plot b). The degree to which δ determines the response is modulated by the degree of interference of factors other than δ such as volitional factors disposing the subject arbitrarily to look one way or the other. This modulation is reflected in the slope of the function. Subjects who are able to minimise such volitional interference, exercising greater power of meta-volition, show steep functions determined sharply by the value of δ (plots c, d). Subjects who are less able to minimise volitional interference, reflecting weaker powers of meta-volition, show flatter functions less sharply determined by the value of δ (plots a, b). The slope is thus the measure of meta-volition. See Fig. 3 for plots of the functions of each participant in the experiment