Making faces in the brain

Some regions of the inferior temporal cortex (IT) respond with high selectivity to faces. Afraz et al. have shown a causal link between activity of these region and actual face perception measured behaviorally. Artificially activating the right neurons at the right time causes visual perception of a face. This new result shows that such neurons directly underlie the recognition of complex objects. Their abstract:

"The inferior temporal cortex (IT) of primates is thought to be the final visual area in the ventral stream of cortical areas responsible for object recognition. Consistent with this hypothesis, single IT neurons respond selectively to highly complex visual stimuli such as faces. However, a direct causal link between the activity of face-selective neurons and face perception has not been demonstrated. In the present study of macaque monkeys, we artificially activated small clusters of IT neurons by means of electrical microstimulation while the monkeys performed a categorization task, judging whether noisy visual images belonged to 'face' or 'non-face' categories. Here we show that microstimulation of face-selective sites, but not other sites, strongly biased the monkeys' decisions towards the face category. The magnitude of the effect depended upon the degree of face selectivity of the stimulation site, the size of the stimulated cluster of face-selective neurons, and the exact timing of microstimulation. Our results establish a causal relationship between the activity of face-selective neurons and face perception."

Evidence for stroke-induced neurogenesis in the human brain

The Work of Bhardwaj et. al. mentioned in the Aug. 22 blog posting has made the point that under normal conditions new neurons are not born at detectable levels in the adult human brain. These measurements had a detection limit of ~ 1%, however, and would not have been expected to note small amounts of nerve cell proliferation occurring near areas damaged by stroke. Jin et al. now report in PNAS that in patients with stroke, cells that express markers associated with newborn neurons are present in the ischemic penumbra surrounding cerebral cortical infarcts, where these cells are preferentially localized in the vicinity of blood vessels. These findings suggest that stroke-induced compensatory neurogenesis may occur in the human brain, where it could contribute to postischemic recovery and represent a target for stroke therapy.

Start your own religion....

The invention of religions is a universal characteristic of human cultures. An article by Michael Luo in the Aug. 28 New York Times describes an interesting film project attempting to follow one example. Andy Deemer's film project placed advertisements seeking participants for a very real, albeit unusual, social experiment: take $5,000 to start your own religious movement, in exchange for allowing a film crew to follow you around as you try to get under way. It turns out that 40 to 45 new religious groups are emerging a year, compared with just a handful a year a little over a century ago. The New York City area has long been a hotbed for new religions, as well as the staging ground for overseas religious movements trying to make the leap into America. New religions tend to form in urban areas, where it is much easier to gather an initial group. Some of the movements that began in this country in the New York City area include Hare Krishna, modern incarnations of Wicca and an array of guru-centered groups. Other successful movements include Scientology, probably the most successful religion of the past century; Unification Church, led by the Rev. Sun Myung Moon; Church Universal and Triumphant, a New Age group; and the Universal Life Church.

After interviewing candidates who ranged from genuine to humorous to bizarre, Joshua Boden (35) was chosen to attempt to establish his "Church of Now", a God-optional religion that lists 14 precepts, including, “The only ‘sin’ is not living fully,” and, “This life is the one that counts; this IS your eternal reward.” The religion has elements of Buddhism, Taoism and New Age thinking. Although some of the beliefs might sound unorthodox and nonreligious (“Laughter is a must!”), Mr. Boden is earnest in his beliefs and his desire to establish a spiritual community. The going as been rocky so far. Potential followers indicated the presentation was not persuasive and authoritative ("Believe this!") enough.

More on the impulsive teenage brain

Nature has a feature by Kendall Powell on how teenage brain's work (see also my 7/07 post). Abstracting from that review:

An NIMH research team, led by Jay Giedd, has made a movie of normal brain changes from ages 5 to 20. It reveals that the grey matter thickens in childhood but then thins in a wave that begins at the back of the brain and reaches the front by early adulthood (see movie, below). The process completes itself sooner in girls than in boys. This corresponds to a long-held assumption that adolescence sees the prefrontal cortex regions that handle executive functions 'waking up' and to the conventional wisdom that girls mature faster in this respect.
(Click on the thin rectangular box below this line if you want to start the movie)

A reward centre on overdrive coupled with planning regions not yet fully functional could make an adolescent an entirely different creature to an adult when it comes to seeking pleasure. In adolescents given a medium or large reward, the nucleus accumbens (part of the reward center of the brain) reacts more strongly than in children or adults

A speculation is that the lag between the frontal regions and the reward centre is an evolutionary feature, not a bug. "You need to engage in high-risk behaviour to leave your village and find a mate," and risk-taking soars at just the same time as hormones drive adolescents to seek out sexual partners.... in rodents, primates and even some birds, adolescence is a time of risky business, seeking out same-age peers and fighting with parents, which "all help get the adolescent away from the home territory".

"I don't think we can fight the biology of wanting to take risks and try on different identities. ...As a society, we can give kids creative, positive outlets that do not lead to irreversible mistakes...Attempts to push kids towards safe sex or pharmaceutical temperance shouldn't be expected to succeed if they simply explain consequences....Adolescents have some fundamental qualities to them that are not voluntary and not easily modified by rational, information-based interventions."

A warning...prenatal ultrasound waves disrupt embryonic brain cell migration in mice.

Ang et al report: Neurons of the cerebral neocortex in mammals, including humans, are generated during fetal life in the proliferative zones and then migrate to their final destinations by following an inside-to-outside sequence. The present study examined the effect of ultrasound waves (USW) on neuronal position within the embryonic cerebral cortex in mice. We used a single BrdU injection to label neurons generated at embryonic day 16 and destined for the superficial cortical layers. Our analysis of over 335 animals reveals that, when exposed to USW for a total of 30 min or longer during the period of their migration, a small but statistically significant number of neurons fail to acquire their proper position and remain scattered within inappropriate cortical layers and/or in the subjacent white matter. The magnitude of dispersion of labeled neurons was variable but systematically increased with duration of exposure to USW. These results call for a further investigation in larger and slower-developing brains of non-human primates and continued scrutiny of unnecessarily long prenatal ultrasound exposure.

Are you beautiful??

The following is from a curious website "Beauty Check" at the Univ. of Regensberg, Germany. A summary of the research is given there.

Here are the composite prototypes they offer:






Characteristics of the male "Sexy face" in the comparison to the "unsexy face":

* Browner skin
* Narrower facial shape
* Less fat
* Fuller and more symmetrical lips
* Darker eye brows
* More and darker lashes
* Upper half of the face broader in relation to the lower
* Higher cheek bones
* Prominent lower jaw
* More prominent chin
* No receding brows
* Thinner lids
* No wrinkles between nose and corner of the mouth





Characteristic features of the female "sexy face" in comparison to the "unsexy face":

* Suntanned skin
* Narrower facial shape
* Less fat
* Fuller lips
* Slightly bigger distance of eyes
* Darker, narrower eye brows
* More, longer and darker lashes
* Higher cheek bones
* Narrower nose
* No eye rings
* Thinner lids

Modulation of competing memory systems by distraction

Foerde et al. show that the relative contributions to a learning task of the declarative memory system of the medial temporal lobe (including the hippocampus) and the habit learning system of the striatum (including basal ganglia) can be altered by the presence of a secondary task during learning. If distractions cause the learning to decrease the relative involvement of the declarative system relative to the habit system, then the resulting learning is not as flexibly applied in new situations:

"Different forms of learning and memory depend on functionally and anatomically separable neural circuits [Squire, L. R. (1992) Psychol. Rev. 99, 195–231]. Declarative memory relies on a medial temporal lobe system, whereas habit learning relies on the striatum [Cohen, N. J. & Eichenbaum, H. (1993) Memory, Amnesia, and the Hippocampal System (MIT Press, Cambridge, MA)]. How these systems are engaged to optimize learning and behavior is not clear. Here, we present results from functional neuroimaging showing that the presence of a demanding secondary task during learning modulates the degree to which subjects solve a problem using either declarative memory or habit learning. Dual-task conditions did not reduce accuracy but reduced the amount of declarative learning about the task. Medial temporal lobe activity was correlated with task performance and declarative knowledge after learning under single-task conditions, whereas performance was correlated with striatal activity after dual-task learning conditions. These results demonstrate a fundamental difference in these memory systems in their sensitivity to concurrent distraction. The results are consistent with the notion that declarative and habit learning compete to mediate task performance, and they suggest that the presence of distraction can bias this competition. These results have implications for learning in multitask situations, suggesting that, even if distraction does not decrease the overall level of learning, it can result in the acquisition of knowledge that can be applied less flexibly in new situations."

The Buddha's Biology

I want to mention a book by that I have found to be a useful summary and distillation of correspondences between classical Buddhist psychology and modern psychology and evolutionary biology. Don't let its self-helpy new-agey title put you off (Buddha's Nature: A Practical Guide to Discovering Your Place in the Cosmos). It's by a crazy guy named Wes Nisker, a stand up Buddhist comic and veteran of the sixties and seventies new age San Francisco scene whose other writings include "The Big Bang, The Buddha, and the Baby Boom" and "The Essential Crazy Wisdom". It is a largely accurate descriptions of how Buddhism's four foundations of mindfulness can be taken to correspond to the bottom-up construction of our nervous system and consciousness, and to stages in the evolution of our nervous systems.

Sensing or exploring the nature of our elemental physical existence, our body breathing and homeostasis, is a focus of the Buddha's First Foundation of Mindfulness. This first foundation corresponds to physical elements of the body and homeostasis (regulation of blood flow, body temperature, etc.) These functions center in primitive brain stem structures we share with reptiles and other vertebrates. This core regulates interactions with the physical world elemental to having a self that we seldom think about - like breathing, supporting ourselves against gravity, seeing, tasting, smelling, touching, hearing.

These core structures also regulate our urge to remedy hunger, to have sex, to approach or avoid, to flee or fight when suddenly presented with very threatening situations. Our experience of these primary and instinctual basic drives, in its urgency and automaticity, has a very different quality than our experience of thoughts or more complicated emotions. The Buddha's Second Foundation of Mindfulness rests on the sentience of the nervous system which can note these elemental feelings, impressions of pleasant/unpleasant/neutral/painful, etc. We can, in more quiet moments of reflection or meditation note the more muted `flickers' of these primal forces, appearing and disappearing almost as transient quantal energies.

Our human introspective access to, observation of, emotional feelings more nuanced than the basic drives mentioned above is the focus of the Buddha's third foundation of mindfulness (affection, fear, anger, sadness, playfulness, etc.). These are regulated by a new kind of cortex that appears in mammals between the brain stem and the outer layer of the cortex, usually referred to as the limbic system.

Finally, our higher level cognitive abilities associated with the newer cortex (neocortex) that forms the top layers or our brain - our ability to note how thoughts and feelings are produced, as natural occurrences like breathing or the heartbeat - are a focus of the Buddha's fourth foundation of mindfulness.

Nisker's book has several sections of exercises or meditations useful in sensing layers of the self, its evolutionary nature, and its symbiosis with the external social and physical world.

An RNA gene expressed during cortical development evolved rapidly in humans

I can't say it any better than the abstract by Pollard et al. does:

"The developmental and evolutionary mechanisms behind the emergence of human-specific brain features remain largely unknown. However, the recent ability to compare our genome to that of our closest relative, the chimpanzee, provides new avenues to link genetic and phenotypic changes in the evolution of the human brain. We devised a ranking of regions in the human genome that show significant evolutionary acceleration. Here we report that the most dramatic of these 'human accelerated regions', HAR1, is part of a novel RNA gene (HAR1F) that is expressed specifically in Cajal–Retzius neurons in the developing human neocortex from 7 to 19 gestational weeks, a crucial period for cortical neuron specification and migration. HAR1F is co-expressed with reelin, a product of Cajal–Retzius neurons that is of fundamental importance in specifying the six-layer structure of the human cortex. HAR1 and the other human accelerated regions provide new candidates in the search for uniquely human biology."

The work suggests that protein-coding genes may not be the movers and shakers of human evolution. Rather, the non-coding 'dark matter' of genomes may harbour most of these vital changes, such as the set of 49 HAR regions - with HAR1 having accrued 18 changes in sequence since our divergence from chimpanzees, whereas only 1 or 2 substitutions would have been expected by chance.

No more new neurons for you: Stable neuron numbers from cradle to grave

These are the titles of a review in PNAS and another in Science of a PNAS paper by Bhardwaj et al. that unequivocally settles a hotly contested issue. It had been reported that a large number of neurons stream daily from proliferative layers near the cerebral ventricle to the overlaying neocortex in adult nonhuman primates, raising speculation that new neurons are continuously added to the adult human cerebral cortex. However, this finding could not be confirmed in either the primate or rodent cortex. Bhardwaj et al. took advantage of the integration of 14C, generated by nuclear bomb tests during the Cold War, in DNA to establish the age of neurons in the major areas of the human cerebral neocortex. Together with the analysis of the neocortex from patients who received BrdU, which integrates in the DNA of dividing cells, their results demonstrate that, whereas nonneuronal cells turn over, neurons in the human cerebral neocortex are not generated in adulthood at detectable levels but are generated before birth.

Thus new neurons are not born in the adult human brain, and changes required for memory, learning, and injury repair must involve alterations or growth of connections between existing nerve cells.

Twin Valley Classical Piano Music

Totally unrelated to the subject area of this blog, but for those of you who know me I thought I would mentioned that I've started to put some of the 2006 classical piano recordings that I am doing on this website.

Infant brains detect arithmetic errors

A PNAS paper by Berger et al. demonstrates that as soon as 6-9 months after birth, human infants recognize incorrect solutions to simple arithmetic equations [(e.g., presentation of 1 + 1; one doll on a TV monitor, with another doll added from behind a screen, followed by a solution of 2 (correct) or 1 (incorrect)]. "Infants looked longer at incorrect solutions than at correct ones. Event-related potentials, time-locked to the presentation of the solution, also differed between conditions, with greater negative activity for the incorrect solution condition. Spectral analysis showed a similar pattern to that of adults observing correct and incorrect arithmetical equations. These findings show (i) that the brain network involved in error detection can be identified in infancy and (ii) that this network can support an association between looking time and violation of expectations." This work goes towards resolving a current debate over whether increased looking time in infancy is related to violation of expectations.

B. Alan Wallace's First Revolution in the Mind Sciences: Where's the beef?

A recent mailing from meditationlist (meditationlist@lists.wisc.edu) gives a link to a video recording of a lecture recently given by B. Alan Wallace at Google Headquarters in Mountain View, CA. (On June 1 I posted a condensation of ideas in his recent book "The Attention Revolution"... also see the brief biography at end of this post).

Wallace argues that John Searles position ( "Mental phenomena are caused by neurophysiological processes in the brain and are themselves features of the brain" ) represents an "Illusion of Knowledge." a modern physicalist resistance to using introspection or accepting discoveries made with it, in favor of focus on behavioral and neural correlates of mental phenomena. He suggests an analogy with medieval theological resistance to Galileo, the refusal to use the telescope or accept discoveries made with it. He thinks that there should be a long delayed revolution in the mind sciences, to finally take up the challenges of William James ("Introspective Observation is what we have to rely on first and foremost and always..") and Wilhelm Wundt: ("The service which it [the experimental method] can yield consists essentially in perfecting our inner observation...."). He cites the 3,000 year old tradition of awareness training and introspection in Buddhism as one example of an appropriate approach to these goals (and in the discussion period he also mentions, Hindu, native american, and other meditative traditions.)

I'm entirely sympathetic with Wallace's goals and work, but I think that he's setting up a bit of a straw man in his extreme portrayals of physicalists or materialists (many of whom are quite open to any avenue of insight they can find). The problem I think is that his analogy with other scientific revolutions fails on the issue of universality and ability to reproduce basic introspective observations. Galileo's and Darwin's observations and measurements can be reproduced by anyone in any culture having appropriate equipment. In the period after William James' challenge and before the behaviorists' 50+ year death grip on progress in psychology a number of groups pursuing an introspective approach could not agree on many basic observations (Wallace commented on, but did not really address this issue in the discussion period). The introspective and meditative approaches associated with many different cultures and religions don't seem remotely close to yielding a unified introspective description of consciousness and our mental processes that transcends their cultural origins in the way that astronomy and biology do.

Still, I think that the Buddha was the first great human biologist in his astute descriptions of levels of human behavior that corresponds roughly to stages in the biological evolution of our own brains and behavior (see my "Beast Within" essay). The mutual reinforcement of ancient introspective and modern scientific traditions yields some robustness, and perhaps the prospect of an eventual union of materialistic and mentalistic perspectives. Perhaps this will yield the "consciousness meter," analogous to a telescope or microscope, than we are now lacking.

Biography:
Wallace is president of The Santa Barbara Institute for Consciousness Studies. He trained for many years as a monk in Buddhist monasteries in India and Switzerland. He has taught Buddhist theory and practice in Europe and America since 1976 and has served as interpreter for numerous Tibetan scholars and contemplatives, including H. H. the Dalai Lama. After graduating summa cum laude from Amherst College, where he studied physics and the philosophy of science, he earned his M.A. and Ph.D. in religious studies at Stanford University. He has edited, translated, authored, and contributed to more than thirty books on Tibetan Buddhism, medicine, language, and culture, and the interface between science and religion. Dr. Wallace is a primary contributer to meditation research projects, including the Cultivating Emotional Balance project and the Shamatha project.

Wallace's published works include Choosing Reality: A Buddhist View of Physics and the Mind (Snow Lion, 1996), The Taboo of Subjectivity: Toward a New Science of Consciousness (Oxford, 2000), Buddhism and Science: Breaking New Ground (Columbia University Press 2003), Balancing the Mind: A Tibetan Buddhist Approach to Refining Attention (Snow Lion, 2005), and Genuine Happiness: Meditation as the Path to Fulfillment (John Wiley & Sons, 2005)

http://alanwallace.org
http://sbinstitute.com

What your facial muscles are revealing - facial profiling

During hominid evolution an increasing number of complex facial muscles appeared to support an array of emotional expressions that are now universal across modern cultures. The amygdala plays a central role in both interpreting and orchestrating the response to these expressions.

A New York Times article today discusses a very practical use of noting subtle changes in this evolved facial musclulature. It is a key element of behavioral profiling increasingly being used at airports to discern potential terrorists. Work over many years by Paul Ekman at UCSF has generated a detailed catalog of these muscles and how they change in different contexts. He has developed a Facial Action Coding System (FACS) that is now widely used.

Here are some photos provided by Ekman showing several expressions. See if you can recognize them before looking at the captions.

The Neural Basis of Embodyment

Some edited clips from a recent J. Neuroscience article by Arzy et al. :

Embodiment, the sense of being localized within one's physical body, is a fundamental aspect of the self. Recent evidence has started to show that self and body processing require two distinct brain mechanisms, with key loci in the temporoparietal junction (TPJ) - involved in self processing and multisensory integration of body-related information - and the extrastriate body area (EBA) - which responds selectively to human bodies and body parts. Arzy et al have used evoked potential mapping to show that activations in EBA and TPJ code differentially for embodiment and self location, because the location and timing of brain activation depended on whether mental imagery is performed with mentally embodied (EBA) or disembodied (TPJ) self location. In a second experiment, they showed that only EBA activation, related to embodied self location, but not TPJ activation, related to disembodied self location, was modified by the subjects' body position during task performance (supine or sitting). This suggests that embodied self location and actual body location share neural mechanisms.


Figure. To investigate embodiment and self location, subjects were asked to perform two mental-imagery tasks with respect to their own body in response to a schematic front- or back-facing human figure. In an own-body transformation task, (OBT task) subjects were asked to imagine themselves in the position and orientation of a schematic human figure, as shown on a computer screen (bottom row, the correct responses for each task are indicated under each stimulus) Either the right or left hand of the figure was marked, and subjects indicated which hand was marked. In a mirror task (MIR task), the same schematic human figure was shown, but subjects were instructed to imagine that the schematic figure (as shown on the computer screen) was their mirror reflection, as seen from their habitual point of view ( top row, the correct responses for each task are indicated under each stimulus).


Figure. Generators of mirror task (MIR. top row, were localized at the left EBA and of the own body transformation task (OBT, bottom row) at the right TPJ and left EBA


Figure. EBA. The mean (x, y) Talairach coordinates of the EBA are given for several neuroimaging studies. Note the similarity of EBA localization across studies, neuroimaging techniques, and behavioral tasks.

This is scary....Americans at bottom of list in belief in evolution.

From the Science Magazine Policy Forum note by Miller et al.

"Over the past 20 years, the percentage of U.S. adults accepting the idea of evolution has declined from 45% to 40% and the percentage of adults overtly rejecting evolution declined from 48% to 39%. The percentage of adults who were not sure about evolution increased from 7% in 1985 to 21% in 2005...Regardless of the form of the question, one in three American adults firmly rejects the concept of evolution, a significantly higher proportion than found in any western European country...the structure and beliefs of American fundamentalism historically differ from those of mainstream Protestantism in both the United States and Europe. The biblical literalist focus of fundamentalism in the United States sees Genesis as a true and accurate account of the creation of human life that supersedes any scientific finding or interpretation. In contrast, mainstream Protestant faiths in Europe (and their U.S. counterparts) have viewed Genesis as metaphorical and--like the Catholic Church--have not seen a major contradiction between their faith and the work of Darwin and other scientists...the evolution issue has been politicized and incorporated into the current partisan division in the United States in a manner never seen in Europe or Japan. In the second half of the 20th century, the conservative wing of the Republican Party has adopted creationism as a part of a platform designed to consolidate their support in southern and Midwestern states--the "red" states. In the 1990s, the state Republican platforms in seven states included explicit demands for the teaching of "creation science". There is no major political party in Europe or Japan that uses opposition to evolution as a part of its political platform...The broad public acceptance of the benefits of science and technology in the second half of the 20th century allowed science to develop a nonpartisan identification that largely protected it from overt partisanship. That era appears to have closed."

Remembrance of mild moments past: add a little arousal

A recent McGaugh review in Trends in Cognitive Science (Volume 10, Issue 8 , August 2006, Pages 345-347) discusses a PNAS paper by Anderson and colleagues demonstrating that emotionally arousing stimuli enhance long-term memory of immediately preceding neutral stimuli. This fits with with extensive evidence from both human and animal studies indicating that arousal-induced modulation of memory is mediated by β-noradrenergic activation of the amygdala.

(By the way, in my July 20 post on involvement of the Locus Ceruleus in the retrieval of emotional memories I inexplicably neglected to mention that this cluster of nerve cells in the lower brain synthesizes noradrenaline (norepinephrine). Its axons, which project to the amygdala and other cortical areas, can 'spritz' large areas of the cortex during arousal, to enhance both the storage and retrieval of emotional memories.)

McGaugh gives a simplified graphic to summarize the main idea:


Figure - Schematic representation of modulation of memory consolidation by emotional arousal-induced release of adrenal stress hormones and noradrenergic activation of the amygdala. Emotional arousal activates the release of noradrenaline in the basolateral amygdala as well as the release of adrenal stress hormones. The stress hormones then provide increased and sustained noradrenergic activation in the amygdala. The amygdala activation modulates memory consolidation via projections to other brain systems processing memory. (Credit TICS)

The Universe in a Neuron, and vice versa

I wanted to pass on the graphics that appeared in this morning's science section of the New York Times. The images show the surprisingly similar patterns seen in vastly different natural phenomena: a neuron (micrometers wide) and the universe (billions of light-years across). The neuron image is from Mark Miller at Brandeis Univ. and the universe image from a consortium of astrophysicists

Neuron

















Universe

Complex Choices Better Made Unconsciously? A critical exchange...

I thought it worth reproducing a current exchange in Science Magazine:

In their Report "On making the right choice: The deliberation-without-attention effect" (17 Feb., p. 1005), A. Dijksterhuis and colleagues reported the intriguing finding that when participants had to choose among four cars on the basis of various attributes, a period of conscious reflection worsened performance. They took this as evidence that complex choices are better when made unconsciously. A close examination of their methods, however, suggests a less startling interpretation.

Because of the easily confusable statements about the four cars, the 4-min period of reflection would cause considerable memory interference and leave participants utterly confused (was it the Hatsdun that had good handling and the Kaiwa no cupholders, or the other way round?). Memory research in the Bartlettian tradition has revealed many examples of such self-generated interference (1). The unconscious group made their decision after a similar 4-min period filled with a distractor task. Knowing that they would have no further opportunity for reflection prior to being required to make their choice, these individuals probably just made their decision at the end of the study period based on their overall impression of which car was best. This alternative account makes a simple and testable prediction, namely, that memory recall will be worse in the conscious condition.

An interesting but unnoted aspect of the findings was that the deliberation group chose the best car on only about 25% of occasions, exactly at chance. Does conscious deliberation yield no more than random results? The alternative account suggested here offers an explanation: It must have been because these individuals were faced with an insurmountable memory challenge and were completely confused about which attributes went with which car.

In any event, the decision problem presented in this study is very unlike the way we normally deliberate about a problem. When choosing between cars, we don't expend effort struggling to recall their attributes; we familiarize ourselves with the relevant attributes during the information search stage, and if we can't recall some attribute, we find it out. Dijksterhuis et al.'s findings would be altogether more compelling if they were replicated in a situation in which the 4-min deliberation period was spent studying the cars' attributes. But the likelihood is that under such circumstances, the best alternative would be selected by close to 100% of participants.

Reference 1. H. L. Roediger, E. T. Bergman, M. L. Meade, in Bartlett, Cognition and Culture, A. Saito, Ed. (Routledge, London, 2000), pp. 115-134.

David R. Shanks
Department of Psychology
University College London
Gower Street
London WC1E 6BT, UK

Response
In our work on the "Deliberation-without-attention" effect, we found that, under complex decision circumstances, unconscious thinkers made better decisions than conscious deliberators. Conscious deliberators suffer from the low memory capacity of consciousness, which renders it impossible for them to take into account substantial amounts of information simultaneously. Unconscious thinkers, on the other hand, are not negatively affected by such capacity constraints. Shanks offers alternative explanations for our findings for both conscious deliberators and unconscious thinkers.

Shanks argues that our conscious thinkers may have faced memory problems. However, memory problems are not causing the effects we see. We have shown that even when the statements are presented in blocks (i.e., first all information on car A, then on car B, etc.), conscious deliberation still produces poor results (1). In addition, we have shown that even when people do have all the information at hand during conscious deliberation, it still produces poor results (2).

Shanks's suggestion that unconscious thinkers simply stick to the initial decision they made immediately after processing the information is not correct. In other experiments (1-3), we have compared unconscious thinkers with people who made decisions immediately after having received all the information, and unconscious thinkers performed better. Unconscious thought does lead to changes in preference, and it does so for the better.

Shanks also notes that under complex conditions, decisions made by conscious deliberators are no better than chance. Although conscious deliberation itself cannot be said to be random, the decisions produced by conscious deliberation are under some circumstances not superior to randomly generated decisions. There are moderators at work here, of course (e.g., expertise). Thus, the idea that conscious deliberation before making decisions is always good is simply one of those illusions consciousness creates for us.

Finally, Shanks observed that our experiments do not reflect the way people normally make decisions. This is true, as is usually the case with lab experiments. However, that is exactly the reason we included two field studies in our Report. In the field studies, people made real decisions with real consequences. These studies also confirmed the "deliberation-without-attention" hypothesis.

References 1. A. Dijksterhuis, J. Pers. Soc. Psychol. 87, 586 (2004). 2. A. Dijksterhuis, Z. van Olden, J. Exp. Soc. Psychol., in press. 3. A. Dijksterhuis, L. F. Nordgren, Pers. Psychol. Sci. 1, 95 (2006).

Ap Dijksterhuis
Maarten W. Bos
Loran F. Nordgren
Rick B. van Baaren
Department of Psychology
University of Amsterdam
Roetersstraat 15, 1018 WB
Amsterdam, the Netherlands

"Hare Brain, Tortoise Mind" and "The Wayward Mind"

These are the titles of two books by British psychologist Guy Claxton (see his website) that I think have received less attention than they should. (It seems to me that British and American psychologists group themselves in quite separate worlds.) The first book is a lucid presentation of experimental work that supports Herbert Spenser's dictum "The determined effort causes perversion of thought." Claxton uses the term "undermind" to describe intuitive and integrative processes normally beyond the range of, and can be inhibited by, our focused awareness. Extremes of being indiscriminately intuitive or insisting on lots of high-quality information can block results.

The term 'undermind' hasn't caught on, and the subsequent excellent book "The Wayward Mind" reverts to using the term "unconscious". "The Wayward Mind" is a history of human attempts to explain the unconscious mind, from ancient descriptions of the 'underworld' to the theories of modern neuroscience.

Here are (clipped and truncated) some lines from pp 348-352 of "Wayward Mind" that I like:
"What we call our ‘self’ is an agglomeration of both conscious and unconscious ingredients: cans, needs, dos, oughts, thinks….these constructions hold out an overwhelming temptation: to assume that the “I” is the same in all of them… so that instead of having an intricate web of things that make me Me, I have to create a single imaginary hub around which they all revolve, to which they all refer…the attempt to keep this fiction going, to ‘hold it together’ can become quite tiring and bothersome… If “I” am essentially reasonable, if I imagine that my zones of control – over my own feelings for example – are wider and more robust than they are, then I am going to get in a tangle trying to ‘control myself.’ If I have decided that who I am is clever, attractive, athletic, stable, creating the hub of “I” locks everything together and prevents it moving. It stops Me expanding to include the unconscious, or graciously shrinking to accommodate old age. I can’t enjoy my waywardness, nor see it as an intrinsic part of ME….All the evidence is that a more relaxed attitude toward the bounds of self makes for a richer, easier and more creative life. Perhaps, after all, waywardness in all its forms is in need not so much of explanation, but of a mystified but friendly welcome. We can explain it if we wish, and the brain is beginning to a reasonable job. But the need to explain, when not motivated by the dispassionate curiosity of the scientist, is surely a sign of anxiety: of the desire to tame with words that which is experienced as unsettling.. "