No abstract

Unconscious neural activity has been repeatedly shown to precede and potentially even influence subsequent free decisions. However, to date, such findings have been mostly restricted to simple motor choices, and despite considerable debate, there is no evidence that the outcome of more complex free decisions can be predicted from prior brain signals. Here, we show that the outcome of a free decision to either add or subtract numbers can already be decoded from neural activity in medial prefrontal and parietal cortex 4 s before the participant reports they are consciously making their choice. These choice-predictive signals co-occurred with the so-called default mode brain activity pattern that was still dominant at the time when the choice-predictive signals occurred. Our results suggest that unconscious preparation of free choices is not restricted to motor preparation. Instead, decisions at multiple scales of abstraction evolve from the dynamics of preceding brain activity.T he subjective experience that our voluntary actions are initiated in the conscious mind has been challenged by the finding that the human brain may already start shaping spontaneous decisions even before they enter into conscious awareness (1, 2). Specifically, the human brain can start preparing spontaneous movements up to several seconds before a person believes themselves to be consciously making a decision to move (1-3).To date, such early choice-predictive signals have only been investigated for simple movement decisions (1-6). However, there are several reasons to assess whether preparatory processes also occur for higher-level, more abstract types of decisions. First, the relevance of motor decisions for understanding the neural formation and preparation of intentions has been heavily debated (7,8), mainly because of their reduced complexity (9, 10) and the limited levels of awareness in motor control (11,12). Second, previous studies on predictive signals for motor choices have revealed early information in prefrontal and parietal brain regions. These regions are not generally considered "motor," but they have been sporadically observed in motor preparation (13,14). This invites the question of whether these regions provide only unconscious preparation of motor intentions or a common, task-independent network for preparing multiple types of decisions before awareness. Given the fundamentally different neural processes involved in performing motor acts and mental calculations, identifying overlap between the early choice-predictive signals would be of high relevance because it would point toward a common cerebral starting point for different types of choices.We also aimed to address another question regarding the prediction of free choices. Previous studies (2, 4) have found early choice-predictive information in areas that overlap with the so-called "default mode" network (DMN) (15)(16)(17). For this reason, we also directly investigated the link between our choice-predictive signals and these "off-task" brain signals. Interestingl...