Where is the ball? Behavioral and neural responses elicited by a magic trick

Abstract

We present results from two experiments, in which subjects watched continuous videos of a professional magician repeatedly performing a maneuver in which a ball could “magically” appear under a cup. In all cases, subjects were asked to predict whether the ball would appear under the cup or not, while scalp EEG recordings were performed. Both experiments elicited strong and consistent behavioral and neural responses. In the first experiment, we used two blocks of videos with different probabilities of the ball appearing in the cup and found that, first, based on the behavioral responses, the subjects could track this probability change; and second, the different probabilities modulated the neural responses. In the second experiment, we introduced a control condition in which the magician performed the maneuver under the table, out of subjects' view. Comparing the two conditions (i.e., performing the maneuver within or out of the subjects' view), we found that, first, the magic trick dramatically biased the subjects' behavioral responses; and second, the two conditions led to differential neural responses, in spite of the fact that the stimulus triggering the evoked responses (seeing the ball in the cup) was exactly the same. Altogether, our results show how new insights into sensory and cognitive processing can be obtained using adapted magic tricks. Moreover, the approach of analyzing responses to continuous video presentations offers a more ecological setting compared to classic evoked potential paradigms, which are typically based on presenting static images flashed at the center of the screen.

Magic, Bayes and wows: A Bayesian account of magic tricks

“…We are aware of only three previous studies that investigated neural responses to the experience of magic tricks. The results of all three provide neural evidence that supports the notion of a relatedness between the "wow" effect as surprise signal and Bayesian predictive coding (Parris et al, 2009;Danek et al, 2015;Caffaratti et al, 2016).…”

“…More complex hierarchical Bayesian models of surprise can be used to model the "wow" effect of a large variety of tricks and to correlate these model-based predictions with both, behavioural and physiological measurements. This latter approach seems specially promising in view that only a handful of studies investigated the physiological effect of magic (Parris et al, 2009;Danek et al, 2015;Caffaratti et al, 2016). Crucially, a number of physiological signatures have been already related specifically to Bayesian surprise, such as pupil dilation (Zénon, 2019), the P300 evoked related potential in EEG (Mars et al, 2008;Wacongne et al, 2011;Kolossa et al, 2012;Kopp et al, 2016) and fMRI responses in the dorsal anterior cingulate cortex (Ide et al, 2013;O'Reilly et al, 2013;Schwartenbeck et al, 2016).…”

“…Accordingly, the EEG study revealed differential P300 evoked potentials during repeated viewing of a magic trick compared to control conditions (Caffaratti et al, 2016). The observed P300 responses are known to be evoked during odd-ball paradigms, i.e.…”

“…The link to neural signals has been largely neglected. Only three studies used neural signals to study our response to magic: two closely-related functional magnetic resonance imaging (fMRI) studies localized brain areas involved in the perception of magic (Parris et al, 2009;Danek et al, 2015), while one electroencephalogram (EEG) study focused in the evoked potential related to a "magical" event (Caffaratti et al, 2016).…”

On the cognitive bases of illusionism

“…We do not attempt to define cognitive phenomena simply in terms of their neural correlates, since in that regard we still know next to nothing about the illusion of impossibility; recently, Caffaratti et al (2016) , have measured for the first-time specific changes in brain activity through electrophysiological records during the magician’s manipulations. In keeping with this, the few neuroimaging experiments that have so far measured changes in brain dynamics during the observation of magic effects have found that the same brain areas previously reported during problem solving and conflict monitoring tasks light up when the illusion of impossibility is experienced ( Parris et al, 2009 ; Danek et al, 2015 ).…”