Free Will, continued - Prior unconscious brain activity predicts choices for abstract intentions!

I've been running a thread on free will and neuroscience in this blog, recently noting comments by Nahmias:

...As long as people understand that discoveries about how our brains work do not mean that what we think or try to do makes no difference to what happens, then their belief in free will is preserved. What matters to people is that we have the capacities for conscious deliberation and self-control that I’ve suggested we identify with free will.

...None of the evidence marshaled by neuroscientists and psychologists suggests that those neural processes involved in the conscious aspects of such complex, temporally extended decision-making are in fact causal dead ends. It would be almost unbelievable if such evidence turned up.

Almost unbelievable appears to have happened, with this from Soon et al.. Interestingly, they identified a partial spatial and temporal overlap of choice-predictive signals with activity in the default mode network I reviewed in this past Monday's post. The 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.

And, a chunk from their discussion:

It is interesting that mental calculation, the more complex task, had less predictive lead time than a simple binary motor choice in our previous study. This could tentatively reflect a general limitation of unconscious processing in the sense that unconscious processes might be restricted in their ability to develop or stabilize complex representations such as abstract intentions. It is also worth noting that both studies showed the same dissociation between cortical regions that were predictive of the content versus the timing of the decision. This implies that the formation of an intention to act depends on interactions between the choice-predictive and time-predictive regions. The temporal profile of this interaction is likely to determine when the earliest choice-predictive information is available and might differ between tasks.

There was a partial spatial overlap between the choice-predictive brain regions and the DMN. Interestingly, the state of the DMN (default mode network) during the early preparatory phase still resembled that during off-task or “resting” periods. This lends further credit to the notion that the preparatory signals were not a result of conscious engagement with the task. Furthermore, the spatial and temporal overlap hints at a potential involvement of the DMN in unconscious choice preparation.

To summarize, we directly investigated the formation of spontaneous abstract intentions and showed that the brain may already start preparing for a voluntary action up to a few seconds before the decision enters into conscious awareness. Importantly, these results cannot be explained by motor preparation or general attentional mechanisms. We found that frontopolar and precuneus/posterior cingulate encoded the content of the upcoming decision, but not the timing. In contrast, the pre-SMA predicted the timing of the decision, but not the content.