Fearful expressions gain preferential access to awareness during continuous flash suppression

Eunice Yang, David H. Zald, and Randolph Blake

Emotion 7:882-886 (2007)

Rapid evaluation of ecologically relevant stimuli may lead to their preferential access to awareness. Continuous flash suppression allows assessment of affective processing under conditions in which stimuli have been rendered invisible due to the strongly suppressive nature of dynamic noise relative to static images. The authors investigated whether fearful expressions emerge from suppression into awareness more quickly than images of neutral or happy expressions. Fearful faces were consistently detected faster than neutral or happy faces. Responses to inverted faces were slower than those to upright faces but showed the same effect of emotional expression, suggesting that some key feature or features in the inverted faces remained salient. When using stimuli solely representing the eyes, a similar bias for detecting fear emerged, implicating the importance of information from the eyes in the preconscious processing of fear expressions.

Continuous flash suppression reduces negative afterimages

Naotsugu Tsuchiya & Christof Koch

Nature Neuroscience 8:1096-1101 (2005)

Illusions that produce perceptual suppression despite constant retinal input are used to manipulate visual consciousness. Here we report on a powerful variant of existing techniques, continuous flash suppression. Distinct images flashed successively at ~10 Hz into one eye reliably suppress an image presented to the other eye. The duration of perceptual suppression is at least ten times greater than that produced by binocular rivalry. Using this tool we show that the strength of the negative afterimage of an adaptor was reduced by half when it was perceptual suppressed by input from the other eye. The more completely that adaptor was suppressed, the more strongly that afterimage intensity was reduced. Paradoxically, trial-to-trial visibility of the adaptor did not correlate with the degree of reduction. Our results imply that information of afterimages involves neuronal structures that access input from both eyes but that do not correspond directly to the neuronal correlates of perceptual awareness.

Moniker Maladies – When names sabotage success

Leif D. Nelson, and Joseph P. Simmons

Psychological Science 18:1106-1112 (2007)

In five studies, we found that people like their names enough to unconsciously pursue consciously avoided outcomes that resemble their names. Baseball players avoid strikeouts, but players whose names begin with the strikeout-signifying letter K strikes out more than others (Study 1). All students want As, but students whose names begin with letter associated with poorer performance (C and D) achieve lower grade point averages (GPAs) than do students whose name begin with A and B (Study 2), especially if they like their initials (Study 3). Because lower GPAs lead to lesser graduate schools, students whose names begin with the letters C and D attend lower-ranked law schools than students whose names begin with A and B (Study 4). Finally, in an experimental study, we manipulated congruence between participant’s initials and the labels of prizes and found that participants solve fewer anagrams when a consolation prize shares their first initial than when it does not (Study 5). These findings provide striking evidence that unconsciously desiring negative name-resembling performance outcomes can insidiously undermine the more conscious pursuit of positive outcomes.

Can Left-handedness be switched? Insight from an early switch of handwriting

Stefan Klo¨ppel, Anna Vongerichten, Thilo van Eimeren, Richard S. J. Frackowiak, and Hartwig R. Siebner

Journal of Neuroscience 27:7847-7853 (2007)

“Converted” left-handers are innately left-handed individuals forced as children to write with the right nondominant hand. We asked how a left-to-right handwriting switch shapes cortical sensorimotor representations of finger movement. In 16 adult converted left-handers and age-match groups of 16 consistent right-handers and 16 left-handers, we studies movement-related neuronal activity with functional magnetic resonance imaging while participants performed simple unimanual and bimanual movement with right and left index fingers. In converted left-handers, movement-related activity in the primary sensorimotor hand area (SM1) and caudal dorsal premotor cortex (PMd) of the nondominant left hemisphere correlated with the left-to-right shift in handedness. The motor right-handed converted left-handers had become, the greater the sensorimotor activation in these areas. Between-group comparisons showed that the switch from left to right hand also reinforced movement representations in the dominant right hemisphere. In converted left-handers, the right inferior parietal cortex and lateral PMd were more activated relative to consistent right or left-handers in all motor tasks. These results suggest two distinct neuronal correlates of handedness in human sensorimotor cortex. Although those in executive sensorimotor cortex (i.e., SM1 and adjacent PMd) depend on the hand used throughout life, those in higher-order sensorimotor areas (i.e., inferior parietal cortex and rostrolateral PMd) are invariant and thus cannot be switched to the nondominant hemisphere by educational training.

Paul Broca’s historic cases: high resolution MR imaging of the brains of Leborgne and Lelong

N. F. Dronkers, O. Plaisant, M. T. Iba-Zizen, and E. A. Cabanis

Brain 130:1432-1441 (2007)

In 1861, the French surgeon, Pierre Paul Broca, described two patients who had lost the ability to speak after injury to the posterior inferior frontal gyrus of the brain. Since that time, an infinite number of clinical and functional imaging studies have relied on this brain-behavior relationship as their anchor for the localization of speech functions. Clinical studies of Broca’s aphasia often assume that deficits in these patients are due entirely to dysfunction in Broca’s area, thereby attributing all aspects of the disorder to this one brain region. Moreover, functional imaging studies often rely on activation in Broca’s area as verification that tasks have successfully tapped speech center. Despite these strong assumptions, the range of locations ascribed to Broca’s area varies broadly across studies. In addition, recent findings with language-impaired patients have suggested that other regions also play a role in speech production, some of which are medial to the area originally described by Broca on the lateral surface of the brain. Given the historical significance of Broca’s original patients and the increasing reliance on Broca’s area as a major speech center, we thought it important to re-inspect these brains to determine the precise location of their lesions as well as other possible areas of damage. Here we describe the results of high resolution magnetic resonance imaging of the preserved brains of Broca’s two historic patients. We found that both patients’ lesions extended significantly into medial regions of the brain, in addition to the surface lesions observed by Broca. Results also indicate inconsistencies between the area originally identified by Broca and what is now called Broca’s area, a finding with significant ramifications for both lesion and functional neuroimaging studies of this well-known brain area.

The false fame illusion in people with memories about a previous life

Maarten J.V. Peters, Robert Horselenberg, Marko Jelicic, Harald Merckelbach

Consciousness and Cognition 16:162-169 (2007)

The present study examined whether individuals with full-blown memories of highly implausible events are prone to commit source monitoring errors. Participants reporting previous-life memories and those without such memories completed a false fame task. This task provides an index of source monitoring errors (i.e., misclassifying familiar non-famous names as famous names). Participants with previous-life memories had a greater tendency to judge the names of previously presented non-famous people as famous than control participants. The two groups did not differ in terms of correct recognition of new non-famous names and famous names. Although dissociation, cognitive failures, sleep-related experiences, depressive symptoms, and signs of psychological distress were all significantly higher in participants with previous-life memories than in controls, these variables did not predict the false fame illusion.

Damage to the insula disrupts addiction to cigarette smoking

Nasir H. Naqvi, David Rudrauf, Hanna Damasio, Antoine Bechara

Science 315:531-534 (2007)

A number of brain systems have been implicated in addictive behavior, but none have yet been shown to be necessary for maintaining the addiction to cigarette smoking. We found that smokers with brain damage involving the insula, a region implicated in conscious urge, were more likely than smokers with brain damage not involving the insula to undergo a disruption of smoking addiction, characterized by the ability to quit smoking easily, immediately, without relapse, and without persistence of the urge to smoke. This results suggests that the insula is a critical neural substrate in the addiction to smoking.