Neural correlates of beauty

“What exactly is beauty?”, is an old and unanswered question. It is one of those fringe qualia of consciousness – not a perception but a feeling, like familiarity or certainty, which is attached to a perception. But the criteria for this feeling has never been settled. A recent paper by Ishizu and Zeti (citation below) looks for the traces of beauty in the brain. Here is the abstract:

We wanted to learn whether activity in the same area(s) of the brain correlate with the experience of beauty derived from different sources. 21 subjects took part in a brain-scanning experiment using functional magnetic resonance imaging. Prior to the experiment, they viewed pictures of paintings and listened to musical excerpts, both of which they rated on a scale of 1–9, with 9 being the most beautiful. This allowed us to select three sets of stimuli–beautiful, indifferent and ugly–which subjects viewed and heard in the scanner, and rated at the end of each presentation. The results of a conjunction analysis of brain activity showed that, of the several areas that were active with each type of stimulus, only one cortical area, located in the medial orbito-frontal cortex (mOFC), was active during the experience of musical and visual beauty, with the activity produced by the experience of beauty derived from either source overlapping almost completely within it. The strength of activation in this part of the mOFC was proportional to the strength of the declared intensity of the experience of beauty. We conclude that, as far as activity in the brain is concerned, there is a faculty of beauty that is not dependent on the modality through which it is conveyed but which can be activated by at least two sources–musical and visual–and probably by other sources as well. This has led us to formulate a brain-based theory of beauty.

 

Of course, there are many other areas of the brain involved in beauty but none with the overlap of vision and hearing found in the A1 part of the orbito-frontal cortex. They give a specific location to their area A1 as a reference for other researchers. This seems to be the seat of an abstract sense of beauty. Facial attractiveness activates A1 or very nearby. This is also in the general area associated with pleasure, reward, desire, value evaluation and judgments. The visual and auditory activity in A1 have a different onset after stimulus and so probably do not follow the same path from some other shared area but arrive independently, musical before visual beauty.

 

The caudate nucleus also is activated with an intensity matching experience of beauty but only for visual not auditory stimuli. This area has been associated with romantic love.

 

We might expect that if beauty has an abstract area of activation than ugliness would too. Not so, there seems no overlap of visual and auditory ugliness. Ugliness appears tied to particular sorts of ugliness, not a symmetrical opposite of abstract beauty. It is perhaps an emotional reaction involving fear, disgust or similar.

We did not find activity in A1 of mOFC that correlates positively with the experience of ugly stimuli, although ugliness, too, involves a judgment. Instead, the parametrically modulated activity with the experience of ugliness was confined to the amygdala and left somato-motor cortex. This implies that there may be a functional specialization within the brain for at least two different kinds of judgment, those related to positive, rewarding, experiences and those related to negative ones.

 

Beauty has a specific neural correlate. Its activation probably depends on the individual, the object and the situation. It is a value judgement in the broadest sense, a positive judgement based on pleasure, desire and reward.

ResearchBlogging.org

Ishizu, T., & Zeki, S. (2011). Toward A Brain-Based Theory of Beauty PLoS ONE, 6 (7) DOI: 10.1371/journal.pone.0021852

Conducting consciousness

I have been interested in communication for many years. Not written stuff but oral speech and accompanying non-verbal communication. How is it that we manage a link, a synchrony, a shared perception between two minds.

A recent blog posting in the Scientific American has some interesting things to say about movies, similar to what has been said about stage magic. There are ways to affect the audience and are skilled practitioners of these arts. Here is the link to Maria Konninova’s posting, The Innate Irresistibility of Film.

Of course we start out with a perceptual slight of hand. The movie is discrete frames but we see it as a continuous. This is because the frames per second is close to the natural ‘frames’ of consciousness which is also discrete. Konninova also mentions the control of blinks, eye movements and event breaks.

… researchers are finally beginning to understand what it is that makes the present-day film experience so binding on a profound level – and why it’s often difficult for older movies to keep up. It seems that filmmakers have over the years perfected the way to best capture – and keep – viewers’ attention. Through trial, error, and instinct, Hollywood has figured out how best to cater to the natural dynamic of our attention and how to capitalize on our naïve assumptions about the continuity of space, time, and action.

… blink synchronicity: if we see someone blink, we’ll likely blink right along with him. Film editor Walter Murch noticed that very thing when he was editing Francis Ford Coppola’s The Conversation. When Gene Hackman blinked, there went Murch’s eyes—and that’s precisely where he wanted to place the film cut. Cut at the blinks, and more likely than not, the viewers will perceive the action as continuous. The cut itself will go unnoticed. … People who view the same film tend to synchronize their blinks – and that synchronization reflects the editing of the story. …

When people watch a movie, their eyes tend to follow similar patterns. Even if a scene has no actors, it remains likely that gaze focus will follow the same trajectory between different viewers. And it’s not just the gaze: each viewer’s brain may actually be reacting in similar fashion as well.

In one study, individuals watched the first 30 minutes of The Good, The Bad and the Ugly while their brains were scanned by fMRI. Researchers found that 45% of neocortical activity—including areas implicated in vision, hearing, emotion, language, and multisensory integration—was quite similar for each viewer. That’s almost half the activity of that part of our brain that coordinates our higher cognitive functions. Impressive indeed.

… When people viewed The Red Balloon in a scanner and then divided the film into events, cuts that coincided with significant changes in action predictably activated dorsal frontal and medial temporal areas of the brain—associated with attentional control and motion processing, respectively—in a similar fashion for each viewer.

In the same way that we could learn much about attention from magicians, we could learn much about consciousness from movie editors. Back to the subject of communication, we can also learn from ordinary conversations. It seems that people who are busy talking seem to get on the same wave length. They synchronize their movements and posture, they get a rhythm going in the speech, their mimic each other’s face expressions, they blink together. Hey, they are coordinating their consciousness.

 

Controlling focus of attention

I have long thought of the thalamus as the ‘grand central station’ of the brain. An extension of the spinal cord (the reticular formation) comes through the lower brain and ends in the thalamus. It is the ascending reticular formation that controls consciousness – when it is active, we are aware and when it is quiet, we are not aware. The signals that keep us awake come from the brain stem up the reticular formation into the thalamus, at the thalamic reticular nucleus. The parts of the thalamus seems to be connected to everything else too. It sends signals and receives signals from every part of the cortex and these signals are essential for consciousness. It has input from all the senses which it feeds on to the cortex (bar smell which mostly goes straight to the cortex and reaches the thalamus via the cortex). The thalamus communicates with the basal gangia and receives information on motor commands through them. And on it goes; there seems to be little that does not involve the thalamus directly or indirectly.

Basilis Zikopoulos and Helen Barbas have a series of papers on attention that put the gate to attention in the thalamic reticular nucleus. We have attention that is top-down and centered on the current task, bottom-up and centered on novel sensory input. They imply that there is also attention centered on strong emotional inputs. The thalamic reticular nucleus inhibits contributions to attention. It receives input from the amygdala (the emotional center) and if this is intense, other potential objects of attention are inhibited. The frontal cortex gives input to the same area and may trigger the inhibition of other potential objects of attention to give top-down attention. Input in the same area from the thalamic mediodorsal nucleus may serve the same purpose for bottom-up attention. The strength and priority of these signals would be used by the thalamic reticular nucleus to drive the spotlight of attention.

Here is the abstract from Zikopoulos and Barbas’ recent paper, Pathways for Emotions and Attention Converge on the Thalamic Reticular Nucleus in Primates, in the Journal of Neuroscience:

How do emotional events readily capture our attention? To address this question we used neural tracers to label pathways linking areas involved in emotional and attentional processes in the primate brain (Macaca mulatta). We report that a novel pathway from the amygdala, the brain’s emotional center, targets the inhibitory thalamic reticular nucleus (TRN), a key node in the brain’s attentional network. The amygdalar pathway formed unusual synapses close to cell bodies of TRN neurons and had more large and efficient terminals than pathways from the orbitofrontal cortex and the thalamic mediodorsal nucleus, which similarly innervated extensive TRN sites. The robust amygdalar pathway provides a mechanism for rapid shifting of attention to emotional stimuli. Acting synergistically, pathways from the amygdala and orbitofrontal cortex provide a circuit for purposeful assessment of emotional stimuli. The different pathways to TRN suggest distinct mechanisms of attention to external and internal stimuli that may be differentially disrupted in anxiety and mood disorders and may be selectively targeted for therapeutic interventions.

Is personality fundamental?

When I was 17, I was introduced to the idea of ‘personality’ as a serious psychological concept, starting with extroversion/introversion. I did not believe a word of it – I memorized it – gave it back on the exams – but never believed it. Ever since personality has been in the ‘maybe, but probably not’ category or even the ‘who cares?’ category. I do think that people have patterns of thought and behaviour. People are somewhat predictable. But I cannot see these individual patterns as a very few clear patterns (16 or 4 or 5). Nor can I see them as unchanging in any individual. And most importantly, I do not see them as deep, fundamental, differences in how the brain is built or how it operates. I will try to be more open-minded (but with reservations).

 

Now there is a paper (see citation) that attempts to show differences between the personality types in the ‘big5′ list using the connectivity between brain areas in resting state fMRI. Here is the abstract:

Personality describes persistent human behavioral responses to broad classes of environmental stimuli. Investigating how personality traits are reflected in the brain’s functional architecture is challenging, in part due to the difficulty of designing appropriate task probes. Resting-state functional connectivity (RSFC) can detect intrinsic activation patterns without relying on any specific task. Here we use RSFC to investigate the neural correlates of the five-factor personality domains. Based on seed regions placed within two cognitive and affective ‘hubs’ in the brain—the anterior cingulate and precuneus—each domain of personality predicted RSFC with a unique pattern of brain regions. These patterns corresponded with functional subdivisions responsible for cognitive and affective processing such as motivation, empathy and future-oriented thinking. Neuroticism and Extraversion, the two most widely studied of the five constructs, predicted connectivity between seed regions and the dorsomedial prefrontal cortex and lateral paralimbic regions, respectively. These areas are associated with emotional regulation, self-evaluation and reward, consistent with the trait qualities. Personality traits were mostly associated with functional connections that were inconsistently present across participants. This suggests that although a fundamental, core functional architecture is preserved across individuals, variable connections outside of that core encompass the inter-individual differences in personality that motivate diverse responses.

 

So the general plan seems to be (1) assign personality categories to the subjects using questionaire (2) predict the brain areas that will have connectivity increased for each personality category (3) pick ‘hubs’ that should be connected to the areas of interest and show the extent of connection of each area to the hubs (4) compare connectivity with prediction.

 

This is a similar plan to the one used by one of the authors, DeYoung, in 2010 to try and show areas that were larger/smaller could be predicted by personality categories. Again the abstract:

We used a new theory of the biological basis of the Big Five personality traits to generate hypotheses about the association of each trait with the volume of different brain regions. Controlling for age, sex, and whole-brain volume, results from structural magnetic resonance imaging of 116 healthy adults supported our hypotheses for four of the five traits: Extraversion, Neuroticism, Agreeableness, and Conscientiousness. Extraversion covaried with volume of medial orbitofrontal cortex, a brain region involved in processing reward information. Neuroticism covaried with volume of brain regions associated with threat, punishment, and negative affect. Agreeableness covaried with volume in regions that process information about the intentions and mental states of other individuals. Conscientiousness covaried with volume in lateral prefrontal cortex, a region involved in planning and the voluntary control of behavior. These findings support our biologically based, explanatory model of the Big Five and demonstrate the potential of personality neuroscience (i.e., the systematic study of individual differences in personality using neuroscience methods) as a discipline.

 

I still find the idea of 5 distinct personality traits, frankly, simplistic. It is way too neat and tidy for a complex biological system. However, the group is going about their research in a logical way, so that if personality types (or something similar) are a part of a deep and fundamental aspect of peoples’ thought and behavior, they may show it convincingly. They call their quest ‘personality neuroscience’ – at least they are going for real evidence.

 

ResearchBlogging.org

Adelstein, J., Shehzad, Z., Mennes, M., DeYoung, C., Zuo, X., Kelly, C., Margulies, D., Bloomfield, A., Gray, J., Castellanos, F., & Milham, M. (2011). Personality Is Reflected in the Brain’s Intrinsic Functional Architecture PLoS ONE, 6 (11) DOI: 10.1371/journal.pone.0027633

DeYoung, C., Hirsh, J., Shane, M., Papademetris, X., Rajeevan, N., & Gray, J. (2010). Testing Predictions From Personality Neuroscience: Brain Structure and the Big Five Psychological Science, 21 (6), 820-828 DOI: 10.1177/0956797610370159

Not seeing the trees for the forest

Here is an interesting abstract. It is from a paper by Poljac, de-Wit, Wagemans in Journal of Cognition, Perceptual wholes can reduce the conscious accessibility of their parts.

Humans can rapidly extract object and category information from an image despite surprising limitations in detecting changes to the individual parts of that image. In this article we provide evidence that the construction of a perceptual whole, or Gestalt, reduces awareness of changes to the parts of this object. This result suggests that the rapid extraction of a perceptual Gestalt, and the inaccessibility of the parts that make up that Gestalt, may in fact reflect two sides of the same coin whereby human vision provides only the most useful level of abstraction to conscious awareness.

This is exactly what is expected of a process that gives awareness of an integrated model of world – not awareness of the perceptions that were used to create the model.

Where is the cat?

There is an interesting blog post (here) by W Davies. It was written on April fools day and so may possibly be tongue in cheek – if so – too, too subtle. He is a materialist and his question is “where is the cat?” when he looks at his cat.

I can make a picture of a cat in my head; I can close my mind and think of it. So I’m perceiving this image of a cat. Where is the image? Where is the cat? … my initial answer is that the cat is simply a 1:1 correlate of certain neurological activity in the brain. That is, if you open up my head you won’t see a picture of a cat, but you’d see something that’s the equivalent of it, sort of like the dots and dashes of Morse code are not English characters, but they are equivalents of them. From a materialistic perspective, you’d theoretically be able to interpret the activity in my brain through some technology, and recreate the image of the cat that I am picturing on a screen.

He then recounts the video ‘mind reading’ experiments and concludes that there is a coded picture of his cat in his brain. But he still has a problem.

So when I was asked “where” my mental image of the cat is, that’s why I responded in this way — the image is located in the brain – it’s just in a different format. But really, I’m not satisfied with that answer. Because in my mind I can see (well maybe not see, but certainly perceive) the cat; not the equivalent neural ‘code’, but the actual cat. I know where the neural code is, but I don’t know where the cat is.

Actually there are at least three cats: the reality-cat, the cognitive-cat, and the consciousness-cat. Its like the territory, the map and the traveler. All we are aware of is the consciousness-cat, the other two are invisible. We can only infer them (and we do infer them reliably). Consciousness is the awareness of a constructed model of reality. We are not aware of the cat, we are aware of our model of the world which includes the cat. One thing our conscious model does not include is the construction of itself. We not not model the modeling process. Modeling the modeling gives an infinite regression of Quakers on oats boxes. So why does the model seem so real? That is its purpose – it is a model – it’s supposed to feel real – it’s evolved to feel real – it would be useless if it was not believable.

If you abandon materialism, you still have the same problem. Where is the magic mind-stuff that has the picture of the cat, how did it the cat get there, why does it seem real? The answers are similar too. They amount to the idea that we need to be aware of a model of the cat in a model of the world and believe it. This does not side-step any questions but just makes them harder.

The brain expends a great deal of energy to create the model and make it available to many processes in the brain. It does a good job of make that model useful and believably ‘real’. We have to infer how this is done and progress is being made in understanding it. Have a bit of patience. Don’t panic.

Process of recovering consciousness

There is a recent study by Scheinin of Turku Finland, his team, and collaborators from U of California. (see citation below). They looked for the neural correlates of consciousness. This is a very interesting study.

 

They start with some differences in what is meant by ‘consciousness’. They are looking for the correlates of the ‘state’ of consciousness as shown by responsiveness to a verbal command.

Consciousness research can roughly be divided into two categories: (1) studies on the contents of consciousness and (2) studies on consciousness as a state. Whereas theories on the particular contents of consciousness, such as visual consciousness, argue for the importance of cortical structures, theories focusing on consciousness as a state stress the importance of subcortical or thalamocortical structures. There is limited human data on which brain structures engage to serve this foundation of consciousness. This study was designed to reveal the minimal neural correlates associated with a conscious state. … General anesthesia is often defined as comprising pharmacologically induced unconsciousness (loss of the ability to feel or experience anything), amnesia (forgetfulness), analgesia (lack of pain), and immobility (not moving in response to surgical stimulation) . In this study, without surgical stimulation, the term “anesthesia” is used to describe pharmacologically induced loss of consciousness. Its objective behavioral criterion was unresponsiveness to a verbal command.

 

They are aware of some of the short-comings of using aesthesia to study consciousness and try to eliminate them by: using neuroimaging and pattern analysis to dissociate changes in consciousness from other effects of anesthesia; they use an anesthetic that allows awakening during a constant dosing of the drug; they compare arousal with two different drugs; the use of PET as well as MRI. What were the results?

(The authors) investigated what turns back on when consciousness re-emerges following anesthetic-induced unconsciousness. The structures that activated when consciousness resumed were the brainstem, the thalamus, the hypothalamus, and the ACC (anterior cingulate cotex). Although only limited frontal and parietal activity was observed during the return to consciousness, an active parietal region demonstrated greater functional connectivity with the ACC (and other frontal regions) during the conscious state. These findings reveal a functional network that activates with restored consciousness to enable arousal, the subjective awareness of stimuli, and the behavioral expression of the contents of consciousness. … Arousal-induced activations were mostly localized in deep, phylogenetically old brain structures rather than in the neocortex. …suggesting that these deep brain structures form a common foundation for a conscious state. These structures activate also upon awakening from natural Stage 2 sleep, and their direct stimulation can reverse the unconsciousness of anesthesia or improve behavioral arousal following chronic brain injury. … impaired consciousness or coma is known to result from paramedian thalamic and midbrain infarcts.

 

The activation of the ACC would fit with the test of consciousness in this case being a motor response.

One distinct cortical region activating during the recovery of consciousness was the ACC. This medial prefrontal region has been proposed to play a critical role in consciousness by integrating cognitive-emotional processing with the state of arousal and the intent-to-act. Others suggest that the ACC is a key site of self-regulation of behavior, or might even be involved with the feeling of “free will”. The neuroanatomy of the ACC and its connections with motor control regions suggest that this brain structure acts as the neural interface for translating intentions into actions. This idea is in agreement with studies showing that restored activity in the ACC correlates with the level of responsiveness in brain-injured patients. Our inferior parietal finding may have importance because of its functional connection with the ACC during the conscious state and because of its suggested role in movement intention and motor awareness. In work presented by Desmurget, direct electrical stimulation of the inferior parietal cortex produced in awake brain surgery patients the sensation of a “will to move”. They concluded that conscious intention and motor awareness arise from increased parietal activity before movement execution. This idea fits well with our findings.

 

Recovery of consciousness is seen as a process:

The recovery from anesthesia does not occur all at once, but rather it appears to occur in a bottom-up manner. When emerging from deep anesthesia there will first be signs of autonomic arousal, followed by a slow return of brainstem reflexes, eventually leading to reflexive or uncoordinated somatic movements that occur somewhat before subjects can willfully respond to simple commands. As shown in our results, only minimal cortical activity is necessary at this point. Thus, emergence of a conscious state, the essential foundation of consciousness, precedes the full recovery of neocortical processing required for rich conscious experiences… All of these data are in agreement with the experiences obtained from hydroanencephalic children, who are devoid of nearly the entire cerebral cortex and yet still display conscious-like behavior. Athough these children have clear deficits in experiencing the rich contents of consciousness, they undoubtedly are in a conscious state, supporting the idea that the subcortical areas identified in our study indicate that consciousness as a process involving both the conscious state and the contents of consciousness likely arises from the interaction between cortical and subcortical mechanism working through specific network connectivity within the brain.

Conscious information processing is pictured as a role of frontoparietal connectivity in the neocortex and is linked to the maintenance of the conscious state by the lower brain through the connections between the neocortex and the thalamus.

 

I have had the opinion that consciousness is far too complex a process and far too wide-spread through the brain to be of recent origin. In this model, the ‘state’ of consciousness could be very old while the particulars of the creation of content for say mammals could be more recent.

 

ResearchBlogging.org

Langsjo, J., Alkire, M., Kaskinoro, K., Hayama, H., Maksimow, A., Kaisti, K., Aalto, S., Aantaa, R., Jaaskelainen, S., Revonsuo, A., & Scheinin, H. (2012). Returning from Oblivion: Imaging the Neural Core of Consciousness Journal of Neuroscience, 32 (14), 4935-4943 DOI: 10.1523/JNEUROSCI.4962-11.2012

Juries not being swayed

On Neuroethics and Law Blog (here) there was reference to a paper giving evidence that scan images do not have the effect on juries that has been reported. Let us hope this is true – scans are far too new and difficult to understand in context, to be used in court if they wield undue influence. I have encountered the opposite view, that scan picture have great influence, but it was with out any evidence, at least where I saw it.

 

Here is the abstract:

Recent developments in the neuropsychology of criminal behavior have given rise to concerns that neuroimaging evidence (such as MRI and functional MRI [fMRI] images) could unduly influence jurors. Across four experiments, a nationally representative sample of 1,476 jury-eligible participants evaluated written summaries of criminal cases in which expert testimony was presented in support of a mental disorder as exculpatory. The evidence varied in the extent to which it presented neuroscientific explanations and neuroimages in support of the expert’s conclusion. Despite suggestive findings from previous research, we found no evidence that neuroimagery affected jurors’ judgments (verdicts, sentence recommendations, judgments of the defendant’s culpability) over and above verbal neuroscience – based testimony. A meta-analysis of our four experiments confirmed these findings. In addition, we found that neuroscientific evidence was more effective than clinical psychological evidence in persuading jurors that the defendant’s disorder reduced his capacity to control his actions, although this effect did not translate into differences in verdicts.

 

ResearchBlogging.org

Schweitzer,N.J., Saks, Michael J., Murphy, Emily R., Adina L., Sinnott-Armstrong, Walter, Gaudet, Lyn M. (2011). Neuroimages as Evidence in a Mens Rea Defence: No Impact Psychology, Public Policy, and Law, 17 (3), 357-393

what computes?

Here is a press release from Queens university:

Queen’s University professor Selim Akl has provided additional proof to the theory that nature computes. Dr. Akl (School of Computing) placed rolled oats on a map of Canada, covering the major urban areas. One urban area held the slime mold. The slime mold reached out for the food, creating thin tubes that eventually formed a network mirroring the Canadian highway system.
“By showing species as low as slime mold can compute a network as complex as the Canadian highway system, we were able to provide some evidence that nature computes,” says Dr. Akl.

Humans and human made machines compute (perhaps so do parrots and chimps) but highways and slime molds do not compute. Computing is done with symbols, usually numbers, and with operations on those symbols, usually mathematical or logical operations. There are other ways to arrive at the same solution as a computation, but they are computations just because the end point is the same. Road systems are the way they are because builders were interested in saving time, effort, money. Slime molds are going to save energy while gaining resources. These processes can be modeled mathematically but they are not done in symbolic way.

This attitude has bothered me for years. The mathematics is not more real than the physical thing. Reality is real and mathematics is just a system used to model it. We invented mathematics and it does not exist outside our brains. Nature does not compute except through human thoughts and actions.

It is very interesting that slime molds can reproduce the Canadian highway system with rewards based on the Canadian population distribution – but they did not calculate it – no computation. It was done with biological processes not arithmetic.

Feeling of agency

Why is it so difficult for neuroscience to identify where our self-experience comes from? It seems to involve a number of processes: memory, emotion, perception, action. Knoblich and Sebanz review some work on self. (see citation)

Action has recently become a central topic in research addressing the sense of self because there is converging evidence that the ability to experience oneself as the cause of an action (‘self- agency’) might be the fundamental building block supporting the sense of self in general. In a recent article, Atsushi Sato and Asako Yasuda report a series of elegant and thought-provoking experiments in which they explored the role of prediction for the experience of agency.

 

Here in a nut-shell is the Sato Yasuda protocol:

At the beginning of each of Sato and Yasuda’s experiments, the participants acquired an arbitrary mapping between two actions (left and right button press) and two auditory consequences (high or low tone). Thus, they learned that their action consistently produced a particular auditory effect at a particular time. In the second phase, two factors were varied: the congruency of the auditory effect in relation to the acquired action-effect mapping and the temporal delay between action and effect. The tone following each action either corresponded to the earlier acquired mapping (congruent) or not (incongruent). The temporal delay between action and effect varied between 0 ms and 600 ms. Participants were told that the auditory effects could be the result of their own action or the experimenter’s action. Participants reported to which extent they felt the tone to be a consequence of their own action.

 

The results showed that the congruency between the action and its auditory effect, and the temporal delay contributed independently to the experience of agency. This is the pattern both when the subjects choose when to act and when they reacted to a stimuli. The experience of agency decreased with increased temporal lag.

 

There are a number of conclusions in the original paper:

The authors interpret these findings as evidence that the experience of agency depends on a comparison between the predicted and the actual sensory consequences of an action. This is in line with the internal model theory of motor control, which postulates that for each action that is executed a prediction of its sensory consequences is generated. This prediction is compared with the actual consequences of an action. The larger the discrepancy the less likely it is that one experiences oneself as causing the action.

 

The feeling of agency was affected whether the action was freely chosen or performed in reaction to an external signal but the effects of the temporal delay were more pronounced when actions were freely chosen.

This raises an interesting possibility: in reactive tasks actors might completely lose the experience of agency when there is a long delay between action and effect, whereas in ‘active’ tasks the experience of agency is preserved to a considerable extent. … Using this clever technique the authors were able to demonstrate that the congruency between action and effect and the delay between them had an effect on the experience of agency both for intended and for erroneous actions. This result supports the authors’ assumption that the experience of agency depends on the discrepancy between predicted and actual sensory consequences, regardless of whether an action is intended or is a mistake. However, an additional result qualifies this interpretation: when there was no temporal delay, the experience of agency was less intense for erroneous actions than for intended actions. Thus, the full-fledged experience of agency requires an action to be intended and its effects to be both congruent and temporally contingent (with prediction).

 

The reviewers point out that there are other theories that fit the results.

Some researchers in the field of voluntary action postulate that the sense of agency does not rely on predictive mechanisms, but on a post-hoc evaluation of performed actions. In particular, Wegner has proposed that the ‘illusionary’ feeling of causing an action arises based on priority (thought precedes action), consistency (thought consistent with action), and exclusivity (no alternative causes). In Sato and Yasuda’s experiments priority was always given, because an intention to act preceded the consequence. Exclusivity was never given, because participants believed that another agent could cause the perceived action consequences. Consistency was manipulated in different ways. It was absent or reduced when the action effect was incongruent, when there was a temporal delay between action and effect, and when an erroneous action was made. ..

 

A further explanation for experienced agency for unintentional actions is suggested by recent studies on error monitoring (Yordonova, Van Schie). It is well known that after an erroneous action is selected internal monitoring mechanisms signal that one has committed an error. Such error signals are based on the detection of a conflict that occurred while choosing between several action alternatives rather than on the comparison between the predicted and actual consequences of a specific action selected for

execution. Agency for erroneous actions could be experienced because an error-monitoring signal is used to readjust the system. The readjustment could serve as a direct indication of agency, or it could influence post-hoc evaluations of performed actions. ..

 

In addition to studies using explicit judgments of agency at least two further lines of research have used implicit perceptual measures. Haggard and his colleagues have

demonstrated that an action and its effect are perceived as being closer in time when the consequence is intended. Blakemore and collaborators have shown that the same sensation is experienced as less intense when arising from a self-performed action than when arising

from an other-performed action. It is not yet clear whether such changes in sensation and perception are caused by the same mechanisms that inform explicit judgments of agency.

 

Are these ideas contradictory? I believe not. The prediction and the error-monitoring mechanisms may (I think probably) are the same. And this predictive error system would be an important part of Wegner’s theory.

 

 

ResearchBlogging.org

Knoblich, G., & Sebanz, N. (2005). Agency in the face of error Trends in Cognitive Sciences, 9 (6), 259-261 DOI: 10.1016/j.tics.2005.04.006

Sato, A., & Yasuda, A. (2005). Illusion of sense of self-agency: discrepancy between the predicted and actual sensory consequences of actions modulates the sense of self-agency, but not the sense of self-ownership Cognition, 94 (3), 241-255 DOI: 10.1016/j.cognition.2004.04.003