PSYCH 4320 / COGST 4310 / BioNB 4330

Consciousness and Free Will

Theme I: psychology, philosophy

  Week 2: psychological findings

Week 2: psychological findings

selfhood dissolved: Carhart et al. (2014)

"We propose that within-default-mode network (DMN) resting-state functional connectivity (RSFC) and spontaneous, synchronous oscillatory activity in the posterior cingulate cortex (PCC), particularly in the alpha (8–13Hz) frequency band, can be treated as neural correlates of “ego integrity.” "

[figure: M. Raichle, 2015] "A group of brain areas (a) decrease their activity during task performance. These areas are often referred to as the brain’s default mode network (DMN). If one records the spontaneous fMRI BOLD signal activity in these areas in the resting state (arrows, a) what emerges is a remarkable similarity in the behaviour of the signals between areas (b). Using these fluctuations to analyse the network as a whole reveals a level of functional organization in the ongoing intrinsic activity of the brain (c) that parallels that seen in the task-related activity decreases (a). Analyses of other brain systems (d ) reveal similar levels of functional organization that exist in concert with their subcortical connections (not shown)."

effects of psilocybin on fMRI and MEG measures of brain activity

(A) Decreased CBF [cerebral blood flow] post-psilocybin.

(B) Ventromedial PFC (red) resting state functional connectivity (RSFC) at baseline (top, orange) and decreases post-psilocybin (bottom, blue).

(C) Dorsolateral PFC (red) RSFC at baseline (top, orange) and decreases post-psilocybin (bottom, blue).

(D) Hippocampal (red) RSFC at baseline (top, orange) and decreases post-psilocybin (bottom, blue).

(E) Decreases in oscillatory power (purple) post-psilocybin measured with MEG.

default network activity and alpha oscillations

"Like the DMN, alpha oscillations mature developmentally and evolutionarily (Basar and Guntekin,2009), tempting speculations that these rhythms have developed to reduce “entropy” [i.e., disorder or uncertainty] by increasing mutual information among neuronal ensembles (Tononi etal., 1994).

With this in mind, it was remarkable that we recently found a highly significant positive correlation between the magnitude of alpha power decreases in the PCC after psilocybin and ratings of the item “I experienced a disintegration of my ’self’ or ‘ego’.”"

spectrum of cognitive states

"This schematic is intended to summarize much of what this paper has tried to communicate. [...] It is proposed that normal waking consciousness inhabits a position that is close to criticality* but slightly sub-critical and primary states move brain activity and associated cognition toward a state of increased system entropy i.e., brain activity becomes more random and cognition becomes more flexible."

* The most prominent example is the liquid-vapor critical point, the end point of the pressure-temperature curve that designates conditions under which a liquid and its vapor can coexist. At the critical point, defined by a critical temperature Tc and a critical pressure pc, phase boundaries vanish.

selfhood dissolved: Sass et al. (2013)

"A comparative investigation of anomalous self-experiences common in schizophrenia (defined in Examination of Anomalous Self Experiences (EASE) instrument) and those of normal individuals in an intensely introspective orientation (early 20th-century ‘‘introspectionist’’ psychology)."

ipseity and its disturbance in schizophrenia

"The key disturbance in schizophrenia is a particular disturbance of consciousness and, especially, of the sense of ‘‘minimal self,’’ ‘‘core self,’’ or ipseity that is normally implicit in each act of awareness."

"This self or ipseity disturbance is hypothesized to have two main aspects that may sound mutually contradictory but are in fact compatible or even complementary:

  1. ‘‘Hyperreflexivity’’: a kind of exaggerated self-consciousness, a tendency (fundamentally non-volitional in nature) for focal, objectifying attention to be directed toward processes and phenomena that would normally be ‘‘inhabited’’ or experienced as part of oneself.
  2. ‘‘Diminished self-affection’’: a decline in the (passively or automatically) experienced sense of existing as a living subject of awareness or agent of action."


"Introspection was selected here because it represents perhaps the clearest and purest, non-schizophrenic manifestation of hyperreflexivity, one of the two facets of the ipseity or minimal-self disturbance mentioned above. (Other analogues of interest can be found in various forms of meditative practice [...].)"

"[...] Introspection [...] can involve or engender the majority of the alterations of self-experience that have been found (in past studies and clinical descriptions) to be characteristic of schizophrenia and schizophrenic vulnerability. These include what would appear to involve (at least in the schizophrenic context) rather extreme distortions of normal qualities of experience or thought and a diminishment of the sense of ownership or agentic control over one’s thoughts, feelings, or bodily sensations that is reminiscent of (if not, at times, indistinguishable from) the ‘‘first rank symptoms’’ of schizophrenia (Mellor, 1970)."


"Understanding of one important psychotic development, fragmentation of the self, can be gleaned from considering the introspective analysis of self-experience offered in William James’s chapter on ‘‘The Consciousness of Self’’ in his classic Principles of Psychology (James, 1890/1981). James’s own attempts at introspection show that the introspective demand to locate or specify the experiencing self can result in a shocking ‘‘revelation’’ of the self’s non-existence."

ownership subverted: Botvinick and Cohen (1998)

"Each of ten subjects was seated with their left arm resting upon a small table. A standing screen was positioned beside the arm to hide it from the subject’s view and a life-sized rubber model of a left hand and arm was placed on the table directly in front of the subject. The subject sat with eyes fixed on the artificial hand while we used two small paintbrushes to stroke the rubber hand and the subject’s hidden hand, synchronising the timing of the brushing as closely as possible.

After ten minutes, subjects completed a two-part questionnaire that requested an open-ended description of their experience and asked them to affirm or deny the occurrence of nine specific perceptual effects."

the rubber hand illusion

"The questionnaire included the nine statements shown, presented in a random order. Statements describing the predicted phenomena are underlined. Points indicate mean responses. Bars indicate response range. The questions underlined showed a statistically significant tendency to evoke affirmative responses (p<0.002 for underlined questions, p<0.018 after correcting for multiple comparisons)"

deconstructing the sense of agency: Caspar et al. (2015)

In the active congruent condition, participants performed a voluntary key press with the index finger, and saw the robotic hand replicate the same movement at the same time.

In the passive congruent condition, the experimenter, wearing the glove, pressed the participant’s passive index finger. The experimenter’s finger movement triggered an index finger movement of the robotic hand.

In a third, active incongruent condition, participants again made a voluntary key press with their index finger, but this triggered movement of the little finger of the robotic hand.

deconstructing the sense of agency: the questionnaire

deconstructing the sense of agency

"The present results suggest that acting through a robotic hand intermediary does not necessarily affect the sense of agency, relative to instrumental actions involving only one’s own body (Experiment 1). However, if participants view an intermediary hand that moves in conflict with the intended voluntary motor command, in this case by transposing the movement to a different finger, then the sense of agency was reduced (Experiments 1, 2 and 3).

[...] Human sense of agency appears to [have] two components. The first is a mere statistical contingency between intention and outcome, consistent with some accounts of instrumental learning in animals (Dickenson, 1981). The second component is an appropriate match between the effector-specific content of the voluntary motor command, and the effector involved as the means of producing the outcome appears to be contributed. That is, human sense of agency makes reference to the details of sensorimotor control, as well as to statistical association between events."

[Cf. the recent insights into the causes of schizophrenia, e.g, Cannon, 2015.]

perspectivalness displaced: Ehrsson (2007)

"To provide objective evidence for the [out of body] illusion, I registered the skin conductance response (SCR) as a measure of the emotional response when the illusory body was “hurt” by hitting it with hammer after a period of stimulation. I compared the illusion condition (with synchronous touches) to an asynchronous condition in which the person’s real and illusory chests were touched alternatingly. I observed significantly greater threat-evoked SCRs after the illusion condition (p < 0.013; paired t test) and stronger ratings of the illusion (p < 0.05; paired t test)."

perspectivalness displaced: Blanke and Metzinger (2009)

(a) Experimental setup of the seminal self-observations made at the end of the 19th century by G.M. Stratton.

(b,c) Experimental set-up of the full-body illusion. Participant (physical subject [PS] in dark blue trousers) sees through a head-mounted display (HMD) either a virtual fake body (VF, pink trousers) or a virtual non-corporeal object (VO, light gray) being stroked synchronously or asynchronously with his back. Dark colours indicate the actual location of the physical body/object whereas light colours represent the virtual body/object seen on the HMD. Participants’ self-identification and self-location was modified, leading to self-identification only with the virtual body and a drift in self-location towards the virtual body to an extracorporeal position, especially during synchronous stroking.

(d) Alternative experimental set-up of the full-body illusion. Participant sees through a HMD the own body being stroked synchronously or asynchronously, yet stroking is applied at the chest (unseen) and in front of the camera. This induced the experience of being at the position of the camera that was behind the subjects’ body and diminished self-identification with the virtual body during synchronous stroking.

free will debunked? Libet (1999)

"Freely voluntary acts are preceded by a specific electrical change in the brain (the ‘readiness potential’, RP) that begins 550 ms before the act. Human subjects became aware of intention to act 350–400 ms after RP starts, but 200 ms. before the motor act. The volitional process is therefore initiated unconsciously. But the conscious function could still control the outcome; it can veto the act. Free will is therefore not excluded. These findings put constraints on views of how free will may operate; it would not initiate a voluntary act but it could control performance of the act. The findings also affect views of guilt and responsibility.

But the deeper question still remains: Are freely voluntary acts subject to macrodeterministic laws or can they appear without such constraints, non-determined by natural laws and ‘truly free’? I shall present an experimentalist view about these fundamental philosophical opposites."

Libet's clock

"Spot of light revolves around periphery of screen, once in 2.56 sec. (instead of 60 sec. for a sweep-second hand of a regular clock). Each marked off ‘second’ (in the total of 60 markings) represents 43 msec. of actual time here. The subject holds his gaze to the centre of the screen. For each performed quick flexion of the wrist, at any freely chosen time, the subject was asked to note the position of the clock spot when he/she first became aware of the wish or intention to act. This associated clock time is reported by the subject later, after the trial is completed."

the time line of a free act

"The sequence of events, cerebral and subjective, that precede a fully self-initiated voluntary act. Relative to 0 time, detected in the electromyogram (EMG) of the suddenly activated muscle, the readiness potential (RP) (an indicator of related cerebral neuronal activities) begins first, at about –1050 ms. when some pre-planning is reported (RP I) or about –550 ms. with spontaneous acts lacking immediate pre planning (RP II). Subjective awareness of the wish to move (W) appears at about –200 ms., some 350 ms. after onset even of RP II; however, W does appear well before the act (EMG). Subjective timings reported for awareness of the randomly delivered S (skin) stimulus average about –50 ms. relative to actual delivery time. (From Libet, 1989.)"

initiation vs. veto power

"All of us, not just experimental subjects, have experienced our vetoing a spontaneous urge to perform some act. This often occurs when the urge to act involves some socially unacceptable consequence, like an urge to shout some obscenity at the professor. (Incidentally, in the disorder called Tourette’s syndrome, subjects do spontaneously shout obscenities. These acts should not be regarded as freely voluntary. No RP appears before such an act. A quick reaction to an unwarned stimulus also lacks a preceding RP, and it is not a freely voluntary act.)"

"One should, at this point, consider the possibility that the conscious veto itself may have its origin in preceding unconscious processes, just as is the case for the development and appearance of the conscious will. If the veto itself were to be initiated and developed unconsciously, the choice to veto would then become an unconscious choice of which we become conscious, rather than a consciously causal event. [...] I propose that the conscious veto may not require or be the direct result of preceding unconscious processes. The conscious veto is a control function, different from simply becoming aware of the wish to act. There is no logical imperative in any mind–brain theory, even identity theory, that requires specific neural activity to precede and determine the nature of a conscious control function."

conclusions (for now)


thoughts about selves


awareness does not require selfhood,
then the possibility of disrupting various attributes/aspects of the self as we know it — selfhood itself, as well as ownership, agency, and perspectivalness — does not matter a whole lot.

How can we assess awareness independently of selfhood?

we could study the brain under anaesthesia

"There is now considerable evidence that anesthetics modify functional connectivity within and between resting-state cortical networks. Under anesthesia, decreased cortico-cortical connectivity has been reported in higher-order brain networks, including the salience network, the default-mode network (DMN) [...], and the executive control network. In sharp contrast, functional connectivity in low-level sensory cortices is preserved, consistent with the stimulation studies reviewed above that have reported preserved sensory-driven activation in sensory cortex."

Anesthesia and neuroimaging: investigating the neural correlates of unconsciousness,
A. A. MacDonald et al., TiCS 19:100-106 (2015).

anaesthesia and the return of consciousness

"Cortical LFP exemplifying burst suppression (blue) observed in pathological states (e.g., coma, anesthesia). LFP observed in the awake brain is shown in red."

Recovery of consciousness is mediated by a network of discrete metastable activity states,
A. E. Hudson et al., PNAS 111:9283-9288 (2014).

anaesthesia and the return of consciousness

"Time-resolved spectrograms reveal state transitions.
(A) Diagram of the multielectrode array used to record simultaneous activity in the anterior cingulate (C) and retrosplenial (R) cortices, as well as the intralaminar thalamus (T), superimposed on the sagittal brain section.
(B) Time–frequency spectrograms at different anatomical locations during ROC. The power spectral density at each point in time–frequency space indicates the deviation from the mean spectrum on a decibel color scale as the anesthetic concentration is decreased (Bottom) from 1.75% to 0.75% in 0.25% increments until ROC.
(C) Data of the kind shown in B pooled across all animals and all anesthetic concentrations were subjected to PCA. Percent of variance is plotted as a function of the number of PCs. Dynamics of ROC largely are confined to a 3D subspace."

anaesthesia and the return of consciousness

"The network linking the metastable states contains hubs; arrival into the hubs is essential for ROC.
(C) A sphere centered at the cluster centroid shows each cluster. The radius of the sphere is proportional to the total time spent in the cluster. Arrow color shows transition probability. The network of transition probabilities reveals two hubs (blue and green asterisks) defined as the targets of multiple convergent transitions. Awakening was observed in the cluster shown by red asterisks ∼95% of the time. Note that all paths into the “awake” cluster (red asterisks) from burst suppression (any one of the blue spheres) must involve passage first through the burst suppression hub state (blue asterisk) then through the δ-dominant hub (green asterisk)."

"The unifying characteristic of the θ-dominant states (red) is an increase in high-frequency oscillations in the intralaminar thalamus, signifying increased neuronal firing. Note, however, that although the two θ-dominant clusters exhibit similar degrees of thalamic activation, they are distinguished by the degree of cortical recruitment. Thus, although activation of the thalamus is an essential feature of brain activity associated with ROC, its presence is not sufficient to predict activation of the cortex."

conclusions revisited