Friday, March 15, 2013
Newer study on conscious and nonconscious choice
Recall this previous experimental study refuting Libet's experiment, and the ensuing discussion here, here, here, here, here, and here. In that light here are excerpts from this newer study, “Momentary conscious pairing eliminates unconscious-stimulus influences on task selection”:
“Current neuroscientific interest in choices that feel ‘free’ stems largely from Libet's initially unpopular, yet pioneering work using physiological markers to predict choices prior to a participant's own awareness of the ‘urge’ to choose a particular action . The influence of this work was greatly enhanced following Haggard and Eimer's (1999) discovery that lateralized readiness potentials correlated with and predicted conscious choices and subsequent studies have extended this approach to attempt trial-by-trial predictions of free-choices on the basis of physiological markers of unconscious processing . Such predictions exploit natural co-variation in physiological markers of unconscious processes and verbal reports of conscious choices to infer that the former cause the latter. However, the nature of this relationship is far from transparent and has been recently challenged . Schurger and colleagues' experiments and accumulator model suggest that it is only an indirect relationship, mediated by other processes. Moreover, such correlative procedures are conceptually limited in that they cannot distinguish endogenous, unconscious initiation of ‘free willed’ choices  from external control of choices postulated by more radical, ‘illusionist’ perspectives . This latter debate centres on the degree of control that unconsciously-perceived stimuli in our immediate environment can control choices, not as a function of rendering one choice more attractive than another ,  but rather by directly influencing choice mechanisms. Accordingly, some recent work has adopted an alternative approach that promises to reveal more directly the origins of control over our choices.
“The current findings reinforce the conclusions of previous work , ,  that activation of task selection by unconscious stimuli can influence the efficiency of cued task selection and can bias participants to select one of two tasks in a ‘free’ choice procedure. Such influences appear to undermine the folk psychological intuition that our choices (whether cued or ‘freely’ chosen) are ultimately under our conscious, considered control rather than exogenous and unconscious processes. Indeed, these very types of influence have been cited as evidence that human adults' assumption of ‘free’ (independent of immediate environmental control) over their choices must be delusory.
“A second, novel feature of our findings was that in both cued and free-choice task selection paradigms that conscious perception of a prime shape prior to an instruction to perform a task (and subsequent performance of that task) seems to prevent any further control of task selection by those unconscious shapes. Should this pattern of findings prove to generalise across paradigms (we have replicated it in one further set of conditions, not reported here for brevity) this would suggest that unconscious stimuli can control task selection processes only when they are either exclusively unconscious (not conscious on any trials) or explicitly treated as task relevant by the participant. Task-irrelevant, unconscious stimuli that sometimes achieve conscious perception will likely not influence task selection when presented unconsciously; conscious perception of them on some trials would prevent their influence as they did in the studies reported here (indeed, a further study, not reported here intermixed trials in this unpredictable manner and found no influence of the unconscious stimuli).
“At first glance this latter conclusion might not seem to impact the widespread assumption that unconscious stimuli can control task selection. However, we suggest that it greatly narrows the ranges of stimuli in everyday viewing conditions that will be able to control choices. Only task-irrelevant stimuli that are reliably perceived unconsciously such that they can become associated with and influence task selection, yet are never consciously perceived (resulting in suppression of that learning) will be very rare events indeed. Accordingly, our current findings suggest that, beyond the highly controlled conditions of the laboratory, task choices may generally approach independence from unconscious environmental stimuli. That is, our laboratory findings seem broadly to accord with participants' own subjective assessment that their choices are not controlled by stimuli within the immediate environment. Accordingly, these results raise the possibility that participants' assumptions about their own autonomy from immediate environmental control may veridically (to a degree) reflect their autonomy outside the laboratory and only reflect inaccurately environmental control of their decisions within the laboratory- conditions of which they have limited experience.”