The spotlight of our attention blinks ~ 7 times per second

This work argues that when we try to attend to multiple relevant targets we do so sequentially rather regarding them in parallel, at a rate of about 7 items per second. I was unable to download the supplement describing the mathematical details of the psychometric modeling they used to distinguish sequential from parallel. Here is the abstract from the article by VanRullen et al.:

Increasing evidence suggests that attention can concurrently select multiple locations; yet it is not clear whether this ability relies on continuous allocation of attention to the different targets (a "parallel" strategy) or whether attention switches rapidly between the targets (a periodic "sampling" strategy). Here, we propose a method to distinguish between these two alternatives. The human psychometric function for detection of a single target as a function of its duration can be used to predict the corresponding function for two or more attended targets. Importantly, the predicted curves differ, depending on whether a parallel or sampling strategy is assumed. For a challenging detection task, we found that human performance was best reflected by a sampling model, indicating that multiple items of interest were processed in series at a rate of approximately seven items per second. Surprisingly, the data suggested that attention operated in this periodic regime, even when it was focused on a single target. That is, attention might rely on an intrinsically periodic process.

Voluntary movements influence what we see

If our left and right eyes are shown different figures, a competition ensues during which we alternatively perceive one or the other of the figures. Maruya et al. do experiments showing that physical body movements that correlate with one of the figures can enhance the duration of the intervals during which that figure is being seen. This is a nice example of the influence of action on perception. Here is their abstract, a figure, and a clip of their discussion:

Converging lines of evidence point to a strong link between action and perception. In this study, we show that this linkage plays a role in controlling the dynamics of binocular rivalry, in which two stimuli compete for perceptual awareness. Observers dichoptically viewed two dynamic rival stimuli while moving a computer mouse with one hand. When the motion of one rival stimulus was consistent with observers' own hand movements, dominance durations of that stimulus were extended and, remarkably, suppression durations of that stimulus were abbreviated. Additional measurements revealed that this change in rivalry dynamics was not attributable to observers' knowledge about the condition under test. Thus, self-generated actions can influence the resolution of perceptual conflict, even when the object being controlled falls outside of visual awareness.

Figure - Schematic depiction of the rivalry stimuli (a) and diagrams illustrating the four kinds of trials (b). In the experiment, the reversed configuration of the stimuli, with the sphere exposed to the left eye and the grating exposed to the right eye, was also used. In (b), each diagram shows the dots' movement, the observer's hand movement, and the observer's perception of the stimuli, as a function of time. The diagrams in the upper row illustrate the sphere-dominant condition, and the diagrams in the lower row illustrate the sphere-suppressed condition; manual (MAN) trials are shown on the left, and the corresponding automatic trials are shown on the right. The dashed orange outlines indicate the period during which sphere rotation followed the rotation in the training phase, and the green arrows show the correspondence between the sphere-rotation profiles in manual and automatic trials (see the text).

It is well established that the dynamics of binocular rivalry are governed by a host of stimulus variables—including contrast, motion, and figural complexity—that, together, fall within a category defined as "stimulus strength." In our study, motor control behaved as if it, too, belonged in this category. But by what means could motor control affect the stimulus strength of a rival target? One reasonable hypothesis can be derived from the widely held view that visually guided actions are mediated by neural events in brain areas forming the so-called dorsal-stream pathway (Goodale & Milner, 1992). Among other things, this pathway is specialized for visuo-motor transformations underlying motor planning of intentional actions (Andersen & Buneo, 2002). It is also known (Fang & He, 2005) that neural activity within this pathway remains strong during both dominance and suppression phases of binocular rivalry, unlike activity in the ventral-stream pathway, where activity fluctuates during rivalry. Thus, it is conceivable that during both dominance and suppression phases, actions and their visual consequences are registered within dorsal-stream structures involved in the control of visually guided actions. Through feedback, lateral interconnections, or both, this dorsal-stream activity, in turn, could modulate neural events in brain areas where rivalry does transpire.

Scientific Imagery

During 1959-62 I did research on the blood oxygen transport protein Hemoglobin, and I remember how excited I was by the Harvard lectures at which Perutz and Kendrew presented the first three dimensional protein structures determined by X-ray diffraction. The figure at left showing the structure of the muscle oxygen storage protein myoglobin is from a 1962 Scientific American article by Kendrew.

Goodsell and Johnson, in an article in PLoS Biology, describe several of the challenges facing artists who try to represent complex biological structures, who must selectively disclose, distort, and fill in gaps. The article contains several elegant graphics.

Subliminal Smells Can Guide Social Preferences

Here is the abstract of an interesting article by Li et al. in Psychological Science, followed by a figure showing the experimental paradigm:

It is widely accepted that unconscious processes can modulate judgments and behavior, but do such influences affect one's daily interactions with other people? Given that olfactory information has relatively direct access to cortical and subcortical emotional circuits, we tested whether the affective content of subliminal odors alters social preferences. Participants rated the likeability of neutral faces after smelling pleasant, neutral, or unpleasant odors delivered below detection thresholds. Odor affect significantly shifted likeability ratings only for those participants lacking conscious awareness of the smells, as verified by chance-level trial-by-trial performance on an odor-detection task. Across participants, the magnitude of this priming effect decreased as sensitivity for odor detection increased. In contrast, heart rate responses tracked odor valence independently of odor awareness. These results indicate that social preferences are subject to influences from odors that escape awareness, whereas the availability of conscious odor information may disrupt such effects.

Figure - The experimental paradigm. First, participant specific odor detection thresholds were determined using an ascending-staircase procedure. Then, participants completed an odor-detection and likeability judgment task. In this example, the detection threshold was at dilution 20, so dilution 22 was used in the main task. In that task, participants sniffed a bottle, indicated whether or not it contained an odor, viewed a face stimulus, and finally rated the likeability of the face. For a subset of the participants, heart rate was recorded.

Using Neuroimaging to Resolve the Psi Debate

Moulton and Kosslyn offer a study in J. Cog. Neurosci attempting to find evidence for the psi effect in brain imaging experiments. Here is their abstract, followed by some edited clips and a figure from the paper:

Parapsychology is the scientific investigation of apparently paranormal mental phenomena (such as telepathy, i.e., "mind reading"), also known as psi. Despite widespread public belief in such phenomena and over 75 years of experimentation, there is no compelling evidence that psi exists. In the present study, functional magnetic resonance imaging (fMRI) was used in an effort to document the existence of psi. If psi exists, it occurs in the brain, and hence, assessing the brain directly should be more sensitive than using indirect behavioral methods (as have been used previously). To increase sensitivity, this experiment was designed to produce positive results if telepathy, clairvoyance (i.e., direct sensing of remote events), or precognition (i.e., knowing future events) exist. Moreover, the study included biologically or emotionally related participants (e.g., twins) and emotional stimuli in an effort to maximize experimental conditions that are purportedly conducive to psi. In spite of these characteristics of the study, psi stimuli and non-psi stimuli evoked indistinguishable neuronal responses—although differences in stimulus arousal values of the same stimuli had the expected effects on patterns of brain activation. These findings are the strongest evidence yet obtained against the existence of paranormal mental phenomena.

In our experiment, participants played one of two roles: "sender" and "receiver." On each trial, sender participants viewed a randomly selected target stimulus from outside the scanner (see Figure), and tried to send this information to the receiver participant by mental means alone. While the senders were doing this, receiver participants completed a simple binary guessing task, and functional magnetic resonance imaging (fMRI) was used to monitor their brain activity. On each trial of the guessing task, the receivers sequentially viewed two stimuli, guessed which one was the stimulus being "sent" (i.e., the psi stimulus), and then saw the psi stimulus a second time. This paradigm allowed us simultaneously to test all three hypothesized mechanisms of psi: telepathy (i.e., "mind reading"), clairvoyance (i.e., direct sensing of remote events), and precognition (i.e., knowing future events). The sender served as the potential telepathic source, the sender's computer monitor served as the potential clairvoyance source, and the second presentation of the psi stimulus served as the potential precognition source.

Figure 1 A schematic of one trial. In this trial for the receiver, the non-psi stimulus appears first and the psi stimulus second. The third stimulus presentation (feedback) in each trial is always the same as the psi stimulus. The sender sees only the psi stimulus for each trial.

The results support the null hypothesis that psi does not exist. The brains of our participants—as a group and individually—reacted to psi and non-psi stimuli in a statistically indistinguishable manner. Given the relatively large number of participants, the use of fixed-effects statistics, the extensive activation elicited separately by both types of stimuli, the subtle psychological effects revealed in the much smaller data set from a single participant, and the non-psi effects we documented on a group level using identical statistical criteria, a lack of statistical power does not reasonably explain our results. Even if the psi effect were very transient, as are many mental events, it should have left a footprint that could be detected by fMRI—as did the other subtle effects we detected. In particular, the large and massively significant activation revealed by our arousal contrast shows that that the psi effect, if it exists, must be substantially smaller than the effect of arousal on brain activity.

But what of the truism that one cannot affirm the null hypothesis? We note that some null results should be taken more seriously than others. ....Consider the possibility of water on Mars. If a set of close-up images of its surface failed to capture frozen lakes, few would accept the nonexistence of Martian water. Yet if a planetwide analysis of its subsurface soil content failed to show telltale signs of water, most would accept the null hypothesis of a Martian desert. Past null results from parapsychology are comparable to scattered snapshots of the surface in that they measure a small sample of outwardly observable variables. The current neuroimaging approach, however, seeks anomalous knowledge at its source, inside the brain, using methods validated by cognitive neuroscience. It is also exhaustive...the study incorporated methodological variables (e.g., biological and emotional relatedness of participants, evocative stimuli) widely considered to facilitate psi by parapsychologists. As such, the current null results do not simply fail to support the psi hypothesis: They offer strong evidence against it. If these results are replicated over a range of participants and situational contexts, the case will become increasingly strong, with as much certainty as is allowed in science, that psi does not exist.

Brain responses that predict athletic performance

An Italian group, studying a group of expert golfers, has found that before a successful golf putt EEG (electroencephalogram) high-frequency alpha waves (10-12 Hz) over frontal motor areas are smaller in amplitude. Here is their abstract from the Journal of Physiology article:

It is not known whether frontal cerebral rhythms of the two hemispheres are implicated in fine motor control and balance. To address this issue, electroencephalographic (EEG) and stabilometric recordings were simultaneously performed in 12 right-handed expert golfers. The subjects were asked to stand upright on a stabilometric force platform placed at a golf green simulator while playing about 100 golf putts. Balance during the putts was indexed by body sway area. Cortical activity was indexed by the power reduction in spatially-enhanced alpha (8-12 Hz) and beta (13-30 Hz) rhythms during movement, referred to a pre-movement period. It was found that the body sway area displayed similar values in the successful and unsuccessful putts. In contrast, the high-frequency alpha power (about 10-12 Hz) was smaller in amplitude in the successful than in the unsuccessful putts over the frontal midline and the arm and hand region of the right primary sensorimotor area; the stronger the reduction of the alpha power, the smaller the error of the unsuccessful putts (i.e. distance from the hole). These results indicate that high-frequency alpha rhythms over associative, premotor and non-dominant primary sensorimotor areas subserve motor control and are predictive of the golfer’s performance.

The Other-Race Effect -Perceptual Narrowing develops during infancy

We are more susceptible to recognition errors when a target face is from an unfamiliar racial group, rather than our own racial group. This is referred to as the "other race effect." An interesting study from Kelly et al. looks at the development of this effect in human infants under one year of age:

Experience plays a crucial role in the development of face processing. In the study reported here, we investigated how faces observed within the visual environment affect the development of the face-processing system during the 1st year of life. We assessed 3-, 6-, and 9-month-old Caucasian infants' ability to discriminate faces within their own racial group and within three other-race groups (African, Middle Eastern, and Chinese). The 3-month-old infants demonstrated recognition in all conditions, the 6-month-old infants were able to recognize Caucasian and Chinese faces only, and the 9-month-old infants' recognition was restricted to own-race faces. The pattern of preferences indicates that the other-race effect is emerging by 6 months of age and is present at 9 months of age. The findings suggest that facial input from the infant's visual environment is crucial for shaping the face-processing system early in infancy, resulting in differential recognition accuracy for faces of different races in adulthood.

Figure - Sample stimuli from the Chinese male and Middle Eastern female conditions. The habituation face is shown at the top of each triad. The test faces (novel and familiar) are shown underneath.

The stimuli were 24 color images of male and female adult faces (age range = 23–27 years) from four different ethnic groups (African, Asian, Middle Eastern, and Caucasian). All faces had dark hair and dark eyes so that the infants would be unable to demonstrate recognition on the basis of these features. The images were photos of students. The Africans were members of the African and Caribbean Society at the University of Sheffield; the Asians were Han Chinese students from Zhejiang Sci-Tech University, Hangzhou, China; the Middle Easterners were members of the Pakistan Society at the University of Sheffield; and the Caucasians were psychology students at the University of Sheffield.

Blue light changes our brains

A new light sensitive system has recently been discovered in the ganglion cells of the retinas, which send signals to the rest of the brain. These cells contain light sensitive melanopsin, most sensitive to blue wavelengths between 460 and 480 nm. The responses triggered by blue light takes seconds to develop and persist for minutes, unlike the rapid and transient responses of our rod and cone photoreceptor cells. Recent work has shown that brain activity related to a working memory task is maintained (or even increased) by blue (470 nm) monochromatic light exposure, whereas it decreases under green (550 nm) monochromatic light exposure. Vandewalle et al. now show that activation of this system causes changes in brain areas related to working memory:

Figure - activity increase in left thalamus.

"We exposed 15 participants to short duration (50 s) monochromatic violet (430 nm), blue (473 nm), and green (527 nm) light exposures of equal photon flux (1013ph/cm2/s) while they were performing a working memory task in fMRI. At light onset, blue light, as compared to green light, increased activity in the left hippocampus, left thalamus, and right amygdala. During the task, blue light, as compared to violet light, increased activity in the left middle frontal gyrus, left thalamus and a bilateral area of the brainstem consistent with activation of the locus coeruleus.

These results support a prominent contribution of melanopsin-expressing retinal ganglion cells to brain responses to light within the very first seconds of an exposure. The results also demonstrate the implication of the brainstem in mediating these responses in humans and speak for a broad involvement of light in the regulation of brain function."

The internet as a return to oral culture

This piece by Alex Wright in the Dec. 2 NY Times is worth passing on in its entirety. It makes the point that the style of human interaction fostered by social websites such as Facebook, MySpace, and Second Life have much in common with prehistoric oral culture. Humans evolved with speech, not the extremely recent invention of writing.

The growing popularity of social networking sites like Facebook, MySpace and Second Life has thrust many of us into a new world where we make “friends” with people we barely know, scrawl messages on each other’s walls and project our identities using totem-like visual symbols. We’re making up the rules as we go. But is this world as new as it seems?

Academic researchers are starting to examine that question by taking an unusual tack: exploring the parallels between online social networks and tribal societies. In the collective patter of profile-surfing, messaging and “friending,” they see the resurgence of ancient patterns of oral communication. “Orality is the base of all human experience,” says Lance Strate, a communications professor at Fordham University and devoted MySpace user. He says he is convinced that the popularity of social networks stems from their appeal to deep-seated, prehistoric patterns of human communication. “We evolved with speech,” he says. “We didn’t evolve with writing.”

The growth of social networks — and the Internet as a whole — stems largely from an outpouring of expression that often feels more like “talking” than writing: blog posts, comments, homemade videos and, lately, an outpouring of epigrammatic one-liners broadcast using services like Twitter and Facebook status updates (usually proving Gertrude Stein’s maxim that “literature is not remarks”). “If you examine the Web through the lens of orality, you can’t help but see it everywhere,” says Irwin Chen, a design instructor at Parsons who is developing a new course to explore the emergence of oral culture online. “Orality is participatory, interactive, communal and focused on the present. The Web is all of these things.”

An early student of electronic orality was the Rev. Walter J. Ong, a professor at St. Louis University and student of Marshall McLuhan who coined the term “secondary orality” in 1982 to describe the tendency of electronic media to echo the cadences of earlier oral cultures. The work of Father Ong, who died in 2003, seems especially prescient in light of the social-networking phenomenon. “Oral communication,” as he put it, “unites people in groups.” In other words, oral culture means more than just talking. There are subtler —and perhaps more important — social dynamics at work.

Michael Wesch, who teaches cultural anthropology at Kansas State University, spent two years living with a tribe in Papua New Guinea, studying how people forge social relationships in a purely oral culture. Now he applies the same ethnographic research methods to the rites and rituals of Facebook users. “In tribal cultures, your identity is completely wrapped up in the question of how people know you,” he says. “When you look at Facebook, you can see the same pattern at work: people projecting their identities by demonstrating their relationships to each other. You define yourself in terms of who your friends are.”

In tribal societies, people routinely give each other jewelry, weapons and ritual objects to cement their social ties. On Facebook, people accomplish the same thing by trading symbolic sock monkeys, disco balls and hula girls. “It’s reminiscent of how people exchange gifts in tribal cultures,” says Dr. Strate, whose MySpace page lists his 1,335 “friends” along with his academic credentials and his predilection for “Battlestar Galactica.”

As intriguing as these parallels may be, they only stretch so far. There are big differences between real oral cultures and the virtual kind. In tribal societies, forging social bonds is a matter of survival; on the Internet, far less so. There is presumably no tribal antecedent for popular Facebook rituals like “poking,” virtual sheep-tossing or drunk-dialing your friends. Then there’s the question of who really counts as a “friend.” In tribal societies, people develop bonds through direct, ongoing face-to-face contact. The Web eliminates that need for physical proximity, enabling people to declare friendships on the basis of otherwise flimsy connections.

“With social networks, there’s a fascination with intimacy because it simulates face-to-face communication,” Dr. Wesch says. “But there’s also this fundamental distance. That distance makes it safe for people to connect through weak ties where they can have the appearance of a connection because it’s safe.” And while tribal cultures typically engage in highly formalized rituals, social networks seem to encourage a level of casualness and familiarity that would be unthinkable in traditional oral cultures. “Secondary orality has a leveling effect,” Dr. Strate says. “In a primary oral culture, you would probably refer to me as ‘Dr. Strate,’ but on MySpace, everyone calls me ‘Lance.’ ”

As more of us shepherd our social relationships online, will this leveling effect begin to shape the way we relate to each other in the offline world as well? Dr. Wesch, for one, says he worries that the rise of secondary orality may have a paradoxical consequence: “It may be gobbling up what’s left of our real oral culture.” The more time we spend “talking” online, the less time we spend, well, talking. And as we stretch the definition of a friend to encompass people we may never actually meet, will the strength of our real-world friendships grow diluted as we immerse ourselves in a lattice of hyperlinked “friends”?

Still, the sheer popularity of social networking seems to suggest that for many, these environments strike a deep, perhaps even primal chord. “They fulfill our need to be recognized as human beings, and as members of a community,” Dr. Strate says. “We all want to be told: You exist.”

The human mind intuits probability at one year of age.

This interesting work (PDF here) shows that 12 month old infants have expectations about future single events never before seen, based on their likelihood. The authors presented movies in which three identical objects and one different in color and shape bounced randomly inside a container with an open pipe at its base, as in a lottery game. After 13 s, an occluder hid the container and one object, either one of the three identical objects (probable outcome) or else the different one (improbable outcome), exited from the pipe. The infants looked significantly longer when they witnessed the improbable outcome.

The authors also show that it only after ~3 years of age that children can overrule their probabilistic intuition when an experienced frequency of outcome disagrees with prior probability.

The article's introduction (slightly edited) sets the context for the work:

Rational agents should integrate probabilities in their predictions about uncertain future events. However, whether humans can do this, and if so, how this ability originates, are controversial issues. One influential view is that human probabilistic reasoning is severely defective, being affected by heuristics and biases. Another influential view claims that humans are unable to predict future events correctly without experiencing the frequency of past outcomes. Indeed, according to this view, in the environment in which we evolved only "the encountered frequencies of actual events" were available, hence predicting the probability of an event never before observed is meaningless.

A third, largely unexplored view is that intuitions about possible future events ground elementary probabilistic reasoning. Against this view, several classic, although not unchallenged, studies seemingly show that probabilistic reasoning appears late in development and requires frequency information. However, if, as Laplace wrote, probability theory "makes us appreciate with exactitude that which exact minds feel by a sort of instinct", humans must have intuitions about probabilities early in their life. The present work supports this view.

I will survive...

A bit of relief from heavy mind-blogging, from Igudesman and Joo:

The anti-aging pill...

Another approach to finding the elixir of the fountain of youth.... a screening finds a compound 10,000 times more potent than the anti-aging compound resveratrol, obtained from grape skins.

Many researchers are betting that ageing and disease are two sides of the same coin. Here is the abstract of relevant work from Milne et al. in the Nov. 29 Nature, followed by a clip from a Nov. 28 Nature News Feature from Hayden.

Calorie restriction extends lifespan and produces a metabolic profile desirable for treating diseases of ageing such as type 2 diabetes1, 2. SIRT1, an NAD+-dependent deacetylase, is a principal modulator of pathways downstream of calorie restriction that produce beneficial effects on glucose homeostasis and insulin sensitivity. Resveratrol, a polyphenolic SIRT1 activator, mimics the anti-ageing effects of calorie restriction in lower organisms and in mice fed a high-fat diet ameliorates insulin resistance, increases mitochondrial content, and prolongs survival. Here we describe the identification and characterization of small molecule activators of SIRT1 that are structurally unrelated to, and 1,000-fold more potent than, resveratrol. These compounds bind to the SIRT1 enzyme–peptide substrate complex at an allosteric site amino-terminal to the catalytic domain and lower the Michaelis constant for acetylated substrates. In diet-induced obese and genetically obese mice, these compounds improve insulin sensitivity, lower plasma glucose, and increase mitochondrial capacity. In Zucker fa/fa rats, hyperinsulinaemic-euglycaemic clamp studies demonstrate that SIRT1 activators improve whole-body glucose homeostasis and insulin sensitivity in adipose tissue, skeletal muscle and liver. Thus, SIRT1 activation is a promising new therapeutic approach for treating diseases of ageing such as type 2 diabetes.

And, from Hayden's article:

The idea that growing old and growing ill are two sides of the same coin remains controversial. Backers of the concept include David Sinclair of Harvard Medical School who made headlines with findings that a chemical in red wine called resveratrol extends lifespan and might prevent diabetes-like symptoms in mice3 (see also page 712). “I don't see ageing as a disease, but as a collection of quite predictable diseases caused by the deterioration of the body,” Sinclair says.

But others don't see it that way. The University of Michigan's Richard Miller says that Sinclair's characterization is “missing the point in a subtle but important way”. Ageing is a major cause of many diseases, but not the only one, Miller argues. And, he adds, ageing has some effects that aren't considered disease states. “It's important to make a distinction between ageing and disease,” Miller says.

Still, those who differ agree that interfering with the ageing process could help patients who are suffering from age-related disease. Sinclair is already running a clinical trial using resveratrol to prevent diabetes in humans.

Cockroach Art

A review in the Nov. 28 issue of Nature of an exhibition: "The Art of Arthropods". An excerpt:

A Californian entomologist uses insects as living paintbrushes to create abstract art. After loading water-based, non-toxic paints on to the tarsi and abdomens of insects, Steven Kutcher directs his bugs to create their 'masterpieces'.

Kutcher controls the direction and movement of his arthropods — such as hissing cockroaches (pictured), darkling beetles and grasshoppers — by their response to external lighting. The result is controlled and random movements, created in a co-authorship between the artist — with predetermined ideas about colour, form, shape and creative flexibility — and his living brushes.

Kutcher's art is more than just a novelty, because it reveals the hidden world of insect footprints. "When an insect walks on your hand, you may feel the legs move but nothing visible remains, only a sensation," he says. "These works of art render the insect tracks and routes visible, producing a visually pleasing piece."

For more see http://www.BugArtbySteven.com

Emotion as Motion

Richie Davidson and Jeffrey Maxwell do some cute experiments to integrate two different literatures on our approach and withdrawal behaviors. One concerns the localization of approach and avoidance behaviors in the left and right hemispheres, respectively. The lateralization of these processes is very ancient, observed in primitive invertebrates. The other is a description of the general association of flexor (towards the body) movements with approach and extensor (away from the body) movements with avoidance. They do the simple experiment of measuring the reaction time for a subject to point a finger in response to the direction of a flashed image of an arrow pointing away (extension) or towards (flexion).

Legend - Examples of target arrows linked to flexor/extensor movements. On each trial, a single target arrow appeared in either the left or the right target zone (box outline). These target arrows were always flanked by either two diamond distractors or two arrow distractors that fell outside the target zone. Down target arrows pointed both downward and toward the participant. Up target arrows pointed both upward and away from the participant. Down arrows were responded to via finger flexion (i.e., self-directed movements) and up arrows via finger extension (i.e., movements directed away from the self).

The hemispheres were differentially stimulated by presenting the stimuli to either the left (LVF) or right (RVF) visual field. Visual input from the LVF (i.e., the right side of the retinas) projects to visual cortex in the right hemisphere (RH), and visual input from the RVF (i.e., the left side of the retinas) projects to visual cortex in the left hemisphere (LH). Sure enough, facilitation of flexor (compared with approach) responses relative to extensor (compared with avoidant) responses was greater in the LH (i.e., RVF targets) than in the RH (i.e., LVF targets). This pattern of hemispheric specialization was observed to a greater degree the higher participants' self-reported level of daily positive affect and the lower their self-reported level of dispositional anxiety.

Theory of Mind Is Independent of Episodic Memory

This is the title of a brief article by Rosenbaum et al. in the 23 Nov. Science. The authors studied two patients who, as a result of severe traumatic brain injury, lost their ability to consciously recollect personal happenings from their own lives. They applied an array of tests widely used tests known to be sensitive to perspective-taking and Theory of Mind impairment (False belief, animations, sarcasm and empathy, visual perspective-taking/deception). The subjects with brain injury performed as well as controls. These results are at variance with the idea that the ability to simulate or reconstruct one's own past mental states is necessary to imagine the contents of other people's minds. (This doesn't say anything about whether this ability was necessary for the development of Theory of Mind capabilities before the brain injury occurred.)

Evolutionary origins of dance and art...

Natalie Angier does a fascinating piece on evolutionary perspectives on how human dance and art originated. Here are some (slightly edited) clips from her article in the Nov. 27 NY Times science section (whole text here), which emphasize the work of Ellen Dissanayake, an independent scholar affiliated with the University of Washington:

...the creative drive has all the earmarks of being an adaptation on its own. The making of art consumes enormous amounts of time and resources, an extravagance you wouldn’t expect of an evolutionary afterthought. Art also gives us pleasure, she said, and activities that feel good tend to be those that evolution deems too important to leave to chance.

What might that deep-seated purpose of art-making be? Geoffrey Miller and other theorists have proposed that art serves as a sexual display, a means of flaunting one’s talented palette of genes... Ms. Dissanayake has other ideas. To contemporary Westerners, she said, art may seem detached from the real world, an elite stage on which proud peacocks and designated visionaries may well compete for high stakes. But among traditional cultures and throughout most of human history, she said, art has also been a profoundly communal affair, of harvest dances, religious pageants, quilting bees, the passionate town rivalries that gave us the spires of Chartres, Reims and Amiens...engaging in what Ms. Dissanayake calls “artifying,” people can be quickly and ebulliently drawn together, and even strangers persuaded to treat one another as kin. Through the harmonic magic of art, the relative weakness of the individual can be traded up for the strength of the hive, cohered into a social unit ready to take on the world.

She suggests that many of the basic phonemes of art, the stylistic conventions and tonal patterns, the mental clay, staples and pauses with which even the loftiest creative works are constructed, can be traced back to the most primal of collusions — the intimate interplay between mother and child.

After studying hundreds of hours of interactions between infants and mothers from many different cultures, Ms. Dissanayake and her collaborators have identified universal operations that characterize the mother-infant bond. They are visual, gestural and vocal cues that arise spontaneously and unconsciously between mothers and infants, but that nevertheless abide by a formalized code: the calls and responses, the swooping bell tones of motherese, the widening of the eyes, the exaggerated smile, the repetitions and variations, the laughter of the baby met by the mother’s emphatic refrain. The rules of engagement have a pace and a set of expected responses, and should the rules be violated, the pitch prove too jarring, the delays between coos and head waggles too long or too short, mother or baby may grow fretful or bored.

To Ms. Dissanayake, the tightly choreographed rituals that bond mother and child look a lot like the techniques and constructs at the heart of much of our art. “These operations of ritualization, these affiliative signals between mother and infant, are aesthetic operations, too,” she said in an interview. “And aesthetic operations are what artists do. Knowingly or not, when you are choreographing a dance or composing a piece of music, you are formalizing, exaggerating, repeating, manipulating expectation and dynamically varying your theme.” You are using the tools that mothers everywhere have used for hundreds of thousands of generations.

In art, as in love, as in dancing the hora, if you don’t know the moves, you really can’t fake them.

Experiencing beauty in art - a biological basis?

One of the most debated issues in aesthetics is whether beauty may be defined by some objective parameters or whether it merely depends on subjective factors. The first perspective goes back to Plato's objectivist view of aesthetic perception, in which beauty is regarded as a property of an object that produces a pleasurable experience in any suitable viewer. This stance may be rephrased in biological terms by stating that human beings are endowed with species-specific mechanisms that resonate in response to certain parameters present in works of art. The alternative stance is that the viewers' evaluation of art is fully subjective. It is determined by experience and personal values

The above text begins a paper in PLoS ONE from Rizzolatti and colleagues, and addresses this issue. Here is their abstract and one figure from the paper.

Is there an objective, biological basis for the experience of beauty in art? Or is aesthetic experience entirely subjective? Using fMRI technique, we addressed this question by presenting viewers, naïve to art criticism, with images of masterpieces of Classical and Renaissance sculpture. Employing proportion as the independent variable, we produced two sets of stimuli: one composed of images of original sculptures; the other of a modified version of the same images. The stimuli were presented in three conditions: observation, aesthetic judgment, and proportion judgment. In the observation condition, the viewers were required to observe the images with the same mind-set as if they were in a museum. In the other two conditions they were required to give an aesthetic or proportion judgment on the same images. Two types of analyses were carried out: one which contrasted brain response to the canonical and the modified sculptures, and one which contrasted beautiful vs. ugly sculptures as judged by each volunteer. The most striking result was that the observation of original sculptures, relative to the modified ones, produced activation of the right insula as well as of some lateral and medial cortical areas (lateral occipital gyrus, precuneus and prefrontal areas). The activation of the insula was particularly strong during the observation condition. Most interestingly, when volunteers were required to give an overt aesthetic judgment, the images judged as beautiful selectively activated the right amygdala, relative to those judged as ugly. We conclude that, in observers naïve to art criticism, the sense of beauty is mediated by two non-mutually exclusive processes: one based on a joint activation of sets of cortical neurons, triggered by parameters intrinsic to the stimuli, and the insula (objective beauty); the other based on the activation of the amygdala, driven by one's own emotional experiences (subjective beauty).


Figure legend: The original image (Doryphoros by Polykleitos) is shown at the centre of the figure. This sculpture obeys to canonical proportion (golden ratio = 1∶1.618). Two modified versions of the same sculpture are presented on its left and right sides. The left image was modified by creating a short legs∶long trunk relation (ratio = 1∶0.74); the right image by creating the opposite relation pattern (ratio = 1∶0.36). All images were used in behavioral testing. The central image (judged-as-beautiful on 100%) and left one (judged-as-ugly on 64%) were employed in the fMRI study.

An antidepressant that extends lifespan.

In worms, that is. Petrascheck et al. show that mianserin, a serotonin receptor antagonist used as an antidepressant in humans, extends the lifespan of the nematode, Caenorhabditis elegans, by one third. Its action shows similarities to lifespan extension by dietary restriction. One possibility is that mianserin induces a state of perceived — rather than real — starvation. Intriguingly, appetite stimulation is a side effect of mianserin in humans, raising the possibility of linkage between appetite and lifespan.

Morality starts young...

The title of this post is the title of an editor's summary in the Nov. 22 issue of Nature:

The key to successful social interactions is the ability to assess others' intentions — be they friend or foe. A new study in 6- and 10-month-old infants shows that humans engage in social evaluations even earlier than was thought, before they can use language. The infants could evaluate actors on the basis of their social acts — they were drawn towards an individual who helps an unrelated third party to achieve his or her goal, and they avoided an individual who hinders a third party's efforts to achieve a goal. The findings support the claim that precursors to adult-like social evaluation are present even in babies. This skill could be a biological adaptation that may also serve as the foundation for moral thought and action later in life.

Here is a figure from the paper by Hamlin et al. showing the actors being evaluated by the children:

Figure legend: a, Helping and hindering habituation events of experiments 1 and 3. On each trial, the climber (red circle) attempts to climb the hill twice, each time falling back to the bottom of the hill. On the third attempt, the climber is either bumped up the hill by the helper (left panel) or bumped down the hill by the hinderer (right panel). Infants in experiment 1 saw these two events in alternating sequence; infants in experiment 3 saw either a helping or hindering event in alternation with the corresponding neutral event depicted in d. b, Looking time test events of experiments 1 and 3. The climber moves from the top of the hill to sit with the character on the right (left panel) or the left (right panel). c, Pushing-up and pushing-down habituation events of experiment 2. An inanimate object (red circle) rests (left panel) at the bottom of the hill and is pushed up, or rests (right panel) at the top of the hill and is pushed down. Infants saw these two events in alternation. d, Neutral habituation events from helper/neutral (left panel) and hinderer/neutral (right panel) conditions of experiment 3. The neutral character, without interacting with the climber, traces a path identical to that of the helper (left panel) or hinderer (right panel). Each infant saw either the helping or hindering event depicted in a, in alternation with the corresponding neutral event.

Brain changes associated with congenital amusia

About four percent of the population has congenital amusia, a lifelong disability that prevents otherwise normal functioning individuals from developing basic musical skills. The condition has also been variously termed note deafness, tone deafness, or tune deafness. Here is an interesting abstract from Hyde et al. on the amusic brain, along with one figure from the paper:

Congenital amusia (or tone deafness) is a lifelong disorder characterized by impairments in the perception and production of music. A previous voxel-based morphometry (VBM) study revealed that amusic individuals had reduced white matter in the right inferior frontal gyrus (IFG) relative to musically intact controls. However, this VBM study also revealed associated increases in gray matter in the same right IFG region of amusics. The objective of the present study was to better understand this morphological brain anomaly by way of cortical thickness measures that provide a more specific measure of cortical morphology relative to VBM. We found that amusic subjects (n = 21) have thicker cortex in the right IFG and the right auditory cortex relative to musically intact controls (n = 26). These cortical thickness differences suggest the presence of cortical malformations in the amusic brain, such as abnormal neuronal migration, that may have compromised the normal development of a right frontotemporal pathway.

Figure - Group cortical thickness differences. Results from the statistical analysis of data from 21 amusics versus 26 controls are displayed at each vertex of the surface of a standardized brain in terms of a t statistical color map. A, Areas of significant thickness increases in the amusic brain relative to controls. B, areas of significant thickness decreases in the amusic brain relative to controls. Predicted group cortical thickness differences are in pink, and nonpredicted differences in green as follows: right superior precentral gyrus (a), right lateral occipital gyrus (b), right inferior precentral gyrus (c), right middle frontal gyrus (d), left inferior temporal gyrus (e), right anterior cingulate (f), right medial orbital frontal gyrus (g), right inferior temporal gyrus (h), left medial orbital frontal gyrus (i).