Piers L. Cornelissen

Contrast sensitivity and coherent motion detection measured at photopic luminance levels in dyslexics and controls

Development dyslexics perform differently from controls on a number of low level visual tasks. We carried out three experiments to explore some of these differences. Dyslexics have been found to have reduced luminance contrast sensitivity at mesopic luminance levels. We failed to replicate this finding at photopic luminance levels. We also compared the (photopic) coherent motion detection thresholds of groups of child and adult dyslexics with those of age matched controls. Dyslexics were significantly less sensitive to motion. The results are discussed in relation to a recent suggestion that developmental dyslexia may be associated with a magnocellular visual deficit.

Visual cues to female physical attractiveness.

Evolutionary psychology suggests that a womans sexual attractiveness is based on cues of health and reproductive potential. In recent years, research has focused on the ratio of the width of the waist to the width of the hips (the waist–to–hip ratio (WHR)). A low WHR (i.e. a curvaceous body) is believed to correspond to the optimal fat distribution for high fertility, and so this shape should be highly attractive. In this paper we present evidence that weight scaled for height (the body mass index (BMI)) is the primary determinant of sexual attractiveness rather than WHR. BMI is also strongly linked to health and reproductive potential. Furthermore, we show how covariation of apparent BMI and WHR in previous studies led to the overestimation of the importance of WHR in the perception of female attractiveness. Finally, we show how visual cues, such as the perimeter–area ratio (PAR), can provide an accurate and reliable index of an individuals BMI and could be used by an observer to differentiate between potential partners

Female and male perceptions of female physical attractiveness in front-view and profile

Two important cues to female physical attractiveness are body mass index (BMI) and shape. In front view, it seems that BMI may be more important than shape; however, is it true in profile where shape cues may be stronger? There is also the question of whether men and women have the same perception of female physical attractiveness. Some studies have suggested that they do not, but this runs contrary to mate selection theory. This predicts that women will have the same perception of female attractiveness as men do. This allows them to judge their own relative value, with respect to their peer group, and match this value with the value of a prospective mate. To clarify these issues we asked 40 male and 40 female undergraduates to rate a set of pictures of real women (50 in front-view and 50 in profile) for attractiveness. BMI was the primary predictor of attractiveness in both front and profile, and the putative visual cues to BMI showed a higher degree of view-invariance than shape cues such as the waist-hip ratio (WHR). Consistent with mate selection theory, there were no significant differences in the rating of attractiveness by male and female raters.

Optimum body-mass index and maximum sexual attractiveness

Evolutionary psychology suggests that a woman’s sexual attractiveness is based on cues of reproductive potential. We compared two potential cues of body shape and weight. The conventional measure of female body shape is the waist/hip ratio, which has become a major determinant of physical attractiveness. A ratio of 0·7 (a curvaceous body) is said to be the optimum of attractiveness. The waist/hip ratio is thought to represent a fat distribution that leads to maximum fertility. However, anorexic women (who are amenorrhoeic and, therefore, infertile) can have the same waist/hip ratio as normal women, which suggests that this ratio is not a reliable measure of reproductive potential. We suggest that body-mass index is more closely related to fertility and health than waist/hip ratio, and, therefore, should be more important in determination of sexual attractiveness.

A specific and rapid neural signature for parental instinct.

Darwin originally pointed out that there is something about infants which prompts adults to respond to and care for them, in order to increase individual fitness, i.e. reproductive success, via increased survivorship of ones own offspring. Lorenz proposed that it is the specific structure of the infant face that serves to elicit these parental responses, but the biological basis for this remains elusive. Here, we investigated whether adults show specific brain responses to unfamiliar infant faces compared to adult faces, where the infant and adult faces had been carefully matched across the two groups for emotional valence and arousal, as well as size and luminosity. The faces also matched closely in terms of attractiveness. Using magnetoencephalography (MEG) in adults, we found that highly specific brain activity occurred within a seventh of a second in response to unfamiliar infant faces but not to adult faces. This activity occurred in the medial orbitofrontal cortex (mOFC), an area implicated in reward behaviour, suggesting for the first time a neural basis for this vital evolutionary process. We found a peak in activity first in mOFC and then in the right fusiform face area (FFA). In mOFC the first significant peak (p<0.001) in differences in power between infant and adult faces was found at around 130 ms in the 10–15 Hz band. These early differences were not found in the FFA. In contrast, differences in power were found later, at around 165 ms, in a different band (20–25 Hz) in the right FFA, suggesting a feedback effect from mOFC. These findings provide evidence in humans of a potential brain basis for the “innate releasing mechanisms” described by Lorenz for affection and nurturing of young infants. This has potentially important clinical applications in relation to postnatal depression, and could provide opportunities for early identification of families at risk.

Visual word recognition: the first half second.

We used magnetoencephalography (MEG) to map the spatiotemporal evolution of cortical activity for visual word recognition. We show that for five-letter words, activity in the left hemisphere (LH) fusiform gyrus expands systematically in both the posterior-anterior and medial-lateral directions over the course of the first 500 ms after stimulus presentation. Contrary to what would be expected from cognitive models and hemodynamic studies, the component of this activity that spatially coincides with the visual word form area (VWFA) is not active until around 200 ms post-stimulus, and critically, this activity is preceded by and co-active with activity in parts of the inferior frontal gyrus (IFG, BA44/6). The spread of activity in the VWFA for words does not appear in isolation but is co-active in parallel with spread of activity in anterior middle temporal gyrus (aMTG, BA 21 and 38), posterior middle temporal gyrus (pMTG, BA37/39), and IFG.

Characteristics of male attractiveness for women

The results show that a woman’s ratings of male attractiveness can be explained by simple physical characteristics, in particular the waist-chest ratio (WCR). However, unlike female physical attractiveness, it is shape that is important for male attractiveness and not size. Women prefer men whose torso has an “inverted triangle” shape (ie, a narrow waist and a broad chest and shoulders). This is a shape consistent with physical strength and muscle development in the upper body. The BMI of the body is comparatively unimportant. By contrast, for female attractiveness the BMI accounts for more than 74% of the variance and WCR does not even reach significance. This is unlikely to be the result of differences in the way males and females rate the attractiveness of images, because women rate female bodies in exactly the same way that men do, with BMI as the primary determinant of attractiveness.

Activation of the Left Inferior Frontal Gyrus in the First 200 ms of Reading: Evidence from Magnetoencephalography (MEG)

Background It is well established that the left inferior frontal gyrus plays a key role in the cerebral cortical network that supports reading and visual word recognition. Less clear is when in time this contribution begins. We used magnetoencephalography (MEG), which has both good spatial and excellent temporal resolution, to address this question. Methodology/Principal Findings MEG data were recorded during a passive viewing paradigm, chosen to emphasize the stimulus-driven component of the cortical response, in which right-handed participants were presented words, consonant strings, and unfamiliar faces to central vision. Time-frequency analyses showed a left-lateralized inferior frontal gyrus (pars opercularis) response to words between 100–250 ms in the beta frequency band that was significantly stronger than the response to consonant strings or faces. The left inferior frontal gyrus response to words peaked at ∼130 ms. This response was significantly later in time than the left middle occipital gyrus, which peaked at ∼115 ms, but not significantly different from the peak response in the left mid fusiform gyrus, which peaked at ∼140 ms, at a location coincident with the fMRI–defined visual word form area (VWFA). Significant responses were also detected to words in other parts of the reading network, including the anterior middle temporal gyrus, the left posterior middle temporal gyrus, the angular and supramarginal gyri, and the left superior temporal gyrus. Conclusions/Significance These findings suggest very early interactions between the vision and language domains during visual word recognition, with speech motor areas being activated at the same time as the orthographic word-form is being resolved within the fusiform gyrus. This challenges the conventional view of a temporally serial processing sequence for visual word recognition in which letter forms are initially decoded, interact with their phonological and semantic representations, and only then gain access to a speech code.

During Visual Word Recognition, Phonology Is Accessed within 100 ms and May Be Mediated by a Speech Production Code: Evidence from Magnetoencephalography

Debate surrounds the precise cortical location and timing of access to phonological information during visual word recognition. Therefore, using whole-head magnetoencephalography (MEG), we investigated the spatiotemporal pattern of brain responses induced by a masked pseudohomophone priming task. Twenty healthy adults read target words that were preceded by one of three kinds of nonword prime: pseudohomophones (e.g., brein–BRAIN), where four of five letters are shared between prime and target, and the pronunciation is the same; matched orthographic controls (e.g., broin–BRAIN), where the same four of five letters are shared between prime and target but pronunciation differs; and unrelated controls (e.g., lopus–BRAIN), where neither letters nor pronunciation are shared between prime and target. All three priming conditions induced activation in the pars opercularis of the left inferior frontal gyrus (IFGpo) and the left precentral gyrus (PCG) within 100 ms of target word onset. However, for the critical comparison that reveals a processing difference specific to phonology, we found that the induced pseudohomophone priming response was significantly stronger than the orthographic priming response in left IFG/PCG at ∼100 ms. This spatiotemporal concurrence demonstrates early phonological influences during visual word recognition and is consistent with phonological access being mediated by a speech production code.

Cortical Effects of Shifting Letter Position in Letter Strings of Varying Length

Neuroimaging and lesion studies suggest that occipito-temporal brain areas play a necessary role in recognizing a wide variety of objects, be they faces, letters, numbers, or household items. However, many questions remain regarding the details of exactly what kinds of information are processed by the occipito-temporal cortex. Here, we address this question with respect to reading. Ten healthy adult subjects performed a single word reading task. We used whole-head magnetoencephalography to measure the spatio-temporal dynamics of brain responses, and investigated their sensitivity to: (1) lexicality (defined here as the difference between words and consonant strings), (2) word length, and (3) variation in letter position. Analysis revealed that midline occipital activity around 100 msec, consistent with low-level visual feature analysis, was insensitive to lexicality and variation in letter position, but was slightly affected by string length. Bilateral occipito-temporal activations around 150 msec were insensitive to lexicality and reacted to word length only in the timing (and not strength) of activation. However, vertical shifts in letter position revealed a hemispheric imbalance: The right hemisphere activation increased with the shifts, whereas the opposite pattern was evident in the left hemisphere. The results are discussed in the light of Caramazza and Hilliss (1990) model of early reading.