Visual scanning of faces correlates with schizophrenia symptomatology

1. The purpose of this study was to examine whether quantitative measures of visual scanning of faces correlated with the severity of symptoms in patients with schizophrenia. 2. Preattentive visual fixations (fixations less than or equal to 50.1 ms in duration) were measured while 16 subjects with chronic schizophrenia and 38 comparison subjects scanned slides of human faces. 3. A significant inverse correlation was found between the number of preattentive fixations exhibited during 10 seconds of facial scanning and total Brief Psychiatric Rating Scale (BPRS) scores. 4. This study suggests that measures that probe preattentive processing during scanning of faces could represent a novel paradigm for studying the symptoms of schizophrenia.     

Face detection in peripheral vision: do faces pop out?

We examined whether faces can produce a 'pop-out' effect in visual search tasks. In the first experiment, subjects' eye movements and search latencies were measured while they viewed a display containing a target face amidst distractors. Targets were upright or inverted faces presented with seven others of the opposite polarity as an 'around-the-clock' display. Face images were either photographic or 'feature only', with the outline removed. Naive subjects were poor at locating an upright face from an array of inverted faces, but performance improved with practice. In the second experiment, we investigated systematically how training improved performance. Prior to testing, subjects were practised on locating either upright or inverted faces. All subjects benefited from training. Subjects practised on upright faces were faster and more accurate at locating upright target faces than inverted. Subjects practised on inverted faces showed no difference between upright and inverted targets. In the third experiment, faces with 'jumbled' features were used as distractors, and this resulted in the same pattern of findings. We conclude that there is no direct rapid 'pop-out' effect for faces. However, the findings demonstrate that, in peripheral vision, upright faces show a processing advantage over inverted faces.     

Patterns of Visual Scanning as Predictors of Emotion Identification in Normal Aging.

Emotion identification appears to decline with age, and deficient visual scanning may contribute to this effect. Eye movements of 20 older adults (OAs) and 20 younger adults (YAs) with normal saccades were recorded while viewing facial expressions. OAs made fewer fixations overall, and they made a higher proportion of fixations to the lower halves of faces. Topographical distribution of fixations predicted better OA accuracy for identifying disgust than other negative emotions. Impaired OA accuracy for fear and anger was specific to vision, with normal identification of these emotions in the auditory domain. Age-related frontal-lobe atrophy may affect the integrity of the frontal eye fields, with consequent scanning abnormalities that contribute to difficulties in identifying certain emotions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Attention misplaced: The role of diagnostic features in the face-inversion effect.

Inversion disproportionately impairs recognition of face stimuli compared to nonface stimuli arguably due to the holistic manner in which faces are processed. A qualification is put forward in which the first point fixated on is different for upright and inverted faces and this carries some of the face-inversion effect. Three experiments explored this possibility by using fixation crosses to guide attention to the eye or mouth region of the to-be-presented faces in different orientations. Recognition was better when the fixation cross appeared at the eye region than at the mouth region. The face-inversion effect was smaller when the eyes were cued than when the mouth was cued or when there was no cueing. The results suggest that the first facial feature attended to is important for accurate face recognition and this may carry some of the effects of inversion. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Does face inversion change spatial frequency tuning?

The authors examined spatial frequency (SF) tuning of upright and inverted face identification using an SF variant of the Bubbles technique (F. Gosselin & P. G. Schyns, 2001). In Experiment 1, they validated the SF Bubbles technique in a plaid detection task. In Experiments 2a–c, the SFs used for identifying upright and inverted inner facial features were investigated. Although a clear inversion effect was present (mean accuracy was 24% higher and response times 455 ms shorter for upright faces), SF tunings were remarkably similar in both orientation conditions (mean r = .98; an SF band of 1.9 octaves centered at 9.8 cycles per face width for faces of about 6°). In Experiments 3a and b, the authors demonstrated that their technique is sensitive to both subtle bottom-up and top-down induced changes in SF tuning, suggesting that the null results of Experiments 2a–c are real. The most parsimonious explanation of the findings is provided by the quantitative account of the face inversion effect: The same information is used for identifying upright and inverted inner facial features, but processing has greater sensitivity with the former. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Orienting to Eye Gaze and Face Processing.

The author conducted 7 experiments to examine possible interactions between orienting to eye gaze and specific forms of face processing. Participants classified a letter following either an upright or inverted face with averted, uninformative eye gaze. Eye gaze orienting effects were recorded for upright and inverted faces, irrespective of whether the faces were simple, schematic faces or more realistic faces. In contrast, inversion affected orienting to targets appearing along the vertical axis. Switching the contrast between the iris and sclera reversed orienting to eye gaze. Lifting the eyelid to expose more of the iris-sclera contrast led to a potentiation of orienting to eye gaze. Raising the eyebrow alone without the eyelid did not affect orienting. The findings suggest that local perceptual information is critical for orienting to eye gaze and that the effect can occur with a degree of independence from certain types of face processing. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Understanding Others: The Face and Person Construal.

The face is a critical stimulus in person perception, yet little research has considered the efficiency of the processing operations through which perceivers glean social knowledge from facial cues. Integrating ideas from work on social cognition and face processing, the current research considered the ease with which invariant aspects of person knowledge can be extracted from faces under different viewing and processing conditions. The results of 2 experiments demonstrated that participants extracted knowledge pertaining to the sex and identity of faces in both upright and inverted orientations, even when the faces were irrelevant to the task at hand. The results of an additional experiment, however, suggested that although the extraction of person knowledge from faces may occur unintentionally, the process is nonetheless contingent on the operation of a semantic processing goal. The authors consider the efficiency of person construal and the processes that support this fundamental facet of social-cognitive functioning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Face and mouth inversion effects on visual and audiovisual speech perception.

Three experiments examined whether image manipulations known to disrupt face perception also disrupt visual speech perception. Research has shown that an upright face with an inverted mouth looks strikingly grotesque whereas an inverted face and an inverted face containing an upright mouth look relatively normal. The current study examined whether a similar sensitivity to upright facial context plays a role in visual speech perception. Visual and audiovisual syllable identification tasks were tested under 4 presentation conditions: upright face-upright mouth, inverted face-inverted mouth, inverted face-upright mouth, and upright face-inverted mouth. Results revealed that for some visual syllables only the upright face-inverted mouth image disrupted identification. These results suggest that upright facial context can play a role in visual speech perception. A follow-up experiment testing isolated mouths supported this conclusion. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The face of aging: Sensitivity to facial feature relations changes with age.

Fundamental to face processing is the ability to encode information about the spatial relations among facial features (configural information). Using a bizarreness rating paradigm, we found older adults differed from young adults in rating configurally distorted faces (eyes, mouth inverted) as less bizarre across all tested orientations (0° to 180°), and were more vulnerable to orientation effects when faces were rotated beyond 90°. No age-related differences in perception of either unaltered faces or featurally distorted faces (eyes whitened, teeth blackened) occurred. These findings identify changes in sensitivity to configural information as an important factor in age-related differences in face perception. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

No effect of inversion on attentional and affective processing of facial expressions.

The decrease in recognition performance after face inversion has been taken to suggest that faces are processed holistically. Three experiments, 1 with schematic and 2 with photographic faces, were conducted to assess whether face inversion also affected visual search for and implicit evaluation of facial expressions of emotion. The 3 visual search experiments yielded the same differences in detection speed between different facial expressions of emotion for upright and inverted faces. Threat superiority effects, faster detection of angry than of happy faces among neutral background faces, were evident in 2 experiments. Face inversion did not affect explicit or implicit evaluation of face stimuli as assessed with verbal ratings and affective priming. Happy faces were evaluated as more positive than angry, sad, or fearful/scheming ones regardless of orientation. Taken together these results seem to suggest that the processing of facial expressions of emotion is not impaired if holistic processing is disrupted. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Are faces of different species perceived categorically by human observers?

What are the species boundaries of face processing? Using a face-feature morphing algorithm, image series intermediate between human, monkey (macaque), and bovine faces were constructed. Forced-choice judgement of these images showed sharply bounded categories for upright face images of each species. These predicted the perceptual discrimination boundaries for upright monkey-cow and cow-human images, but not human-monkey images. Species categories were also well-judged for inverted face images, but these did not give sharpened discrimination (categorical perception) at the category boundaries. While categorical species judgements are made reliably, only the distinction between primate faces and cow faces appears to be categorically perceived, and only in upright faces. One inference is that humans may judge monkey faces in terms of human characteristics, albeit distinctive ones.     

Perception of faces by patients with localized cortical excisions.

62 12–48 yr old patients with left and right frontal, parieto-occipital, and temporal lesions and 18 16–45 yr old normal controls were given a face-perception task. Two composite symmetrical faces were made by combining the left or right half of a normal face with its corresponding mirror image. S was required to indicate which composite more closely resembled the original face. Regardless of upright or inverted orientation, controls and patients with left-hemisphere lesions exhibited a preference for the left-visual-field composite. Patients with right posterior lesions failed to show a bias in either orientation. Right temporal and parieto-occipital cortex appear to contribute to facial perception, regardless of orientation. (French abstract) (42 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Expression and epitopic conservation of calponin in different smooth muscles and during development

The synaptic organization of the saccade-related neuronal circuit between the superior colliculus (SC) and the brainstem saccade generator was examined in an awake monkey using a saccadic, midflight electrical-stimulation method. When microstimulation (50-100 microA, single pulse) was applied to the SC during a saccade, a small, conjugate contraversive eye movement was evoked with latencies much shorter than those obtained by conventional stimulation. Our results may be explained by the tonic inhibition of premotor burst neurons (BNs) by omnipause neurons that ceases during saccades to allow BNs to burst. Thus, during saccades, signals originating from the SC can be transmitted to motoneurons and seen in the saccade trajectory. Based on this hypothesis, we estimated the number of synapses intervening between the SC and motoneurons by applying midflight stimulation to the SC, the BN area, and the abducens nucleus. Eye position signals were electronically differentiated to produce eye velocity to aid in detecting small changes. The mean latencies of the stimulus-evoked eye movements were: 7.9 +/- 1.0 ms (SD; ipsilateral eye) and 7.8 +/- 0.9 ms (SD; contralateral eye) for SC stimulation; 4.8 +/- 0.5 ms (SD; ipsilateral eye) and 5.1 +/- 0.7 ms (SD; contralateral eye) for BN stimulation; and 3.6 +/- 0.4 ms (SD; ipsilateral eye) and 5.2 +/- 0.8 ms (SD; contralateral eye) for abducens nucleus stimulation. The time difference between SC- and BN-evoked eye movements (about 3 ms) was consistent with a disynaptic connection from the SC to the premotor BNs.     

Detection of emotional faces: Salient physical features guide effective visual search.

In this study, the authors investigated how salient visual features capture attention and facilitate detection of emotional facial expressions. In a visual search task, a target emotional face (happy, disgusted, fearful, angry, sad, or surprised) was presented in an array of neutral faces. Faster detection of happy and, to a lesser extent, surprised and disgusted faces was found both under upright and inverted display conditions. Inversion slowed down the detection of these faces less than that of others (fearful, angry, and sad). Accordingly, the detection advantage involves processing of featural rather than configural information. The facial features responsible for the detection advantage are located in the mouth rather than the eye region. Computationally modeled visual saliency predicted both attentional orienting and detection. Saliency was greatest for the faces (happy) and regions (mouth) that were fixated earlier and detected faster, and there was close correspondence between the onset of the modeled saliency peak and the time at which observers initially fixated the faces. The authors conclude that visual saliency of specific facial features--especially the smiling mouth--is responsible for facilitated initial orienting, which thus shortens detection. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Premotor commands encode monocular eye movements

Binocular coordination of eye movements is essential for stereopsis (depth perception) and to prevent double vision. More than a century ago, Hering and Helmholtz debated the neural basis of binocular coordination. Helmholtz believed that each eye is controlled independently and that binocular coordination is learned. Hering believed that both eyes are innervated by common command signals that yoke the eye movements (Hering's law of equal innervation). Here we provide evidence that Hering's law is unlikely to be correct. We show that premotor neurons in the paramedian pontine reticular formation that were thought to encode conjugate velocity commands for saccades (rapid eye movements) actually encode monocular commands for either right or left eye saccades. However, 66% of the abducens motor neurons, which innervate the ipsilateral lateral rectus muscle, fire as a result of movements of either eye. The distribution of sensitivity to ipsilateral and contralateral eye movements across the abducens motor neuron pool may provide a basis for learning binocular coordination in infancy and adapting it throughout life.     

Anxiety and sensitivity to gaze direction in emotionally expressive faces.

This study investigated the role of neutral, happy, fearful, and angry facial expressions in enhancing orienting to the direction of eye gaze. Photographs of faces with either direct or averted gaze were presented. A target letter (T or L) appeared unpredictably to the left or the right of the face, either 300 ms or 700 ms after gaze direction changed. Response times were faster in congruent conditions (i.e., when the eyes gazed toward the target) relative to incongruent conditions (when the eyes gazed away from the target letter). Facial expression did influence reaction times, but these effects were qualified by individual differences in self-reported anxiety. High trait-anxious participants showed an enhanced orienting to the eye gaze of faces with fearful expressions relative to all other expressions. In contrast, when the eyes stared straight ahead, trait anxiety was associated with slower responding when the facial expressions depicted anger. Thus, in anxiety-prone people attention is more likely to be held by an expression of anger, whereas attention is guided more potently by fearful facial expressions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Glissadic saccades: a possible measure of vigilance

Eight males and eight females participated in a 60-min visual signal detection task requiring saccadic eye movements. The waveforms of saccades were evaluated in terms of glissades, slow eye movements in saccade initiation and termination, as a function of time-on-task. Saccades were categorized as anticipatory, stimulus-elicited, and return saccades; as well as blink-concurrent versus blink-free. The results showed that, for blink-free saccades, the occurrence of glissadic saccades increased with time-on-task for anticipatory and return saccades, but not for stimulus-elicited saccades. Likelihood of blink-concurrent glissadic saccades did not change over time-on-task. The results suggest that an increase in anticipatory and return glissadic saccades over time-on-task may be an index of vigilance decrement.     

Encoding Operations and Recognition Memory for Faces.

Two experiments examined the effects of encoding operations on forced-choice recognition memory for upright and inverted photographs of faces. In Experiment 1, with distractors closely matched to targets, performance was better on upright than on inverted faces, but was unaffected by whether subjects judged faces for distinctive features, distinctive traits or distinctive expressions. In Experiment 2, where distractors were either absent or weakly matched to distractors, accuracy was again higher on upright than on inverted faces, and was similar for the three encoding operations on upright faces. In contrast, it was poorer for distinctive expression judgments than for distinctive feature or for distinctive trait judgments on inverted faces. These results support Winograd's (1981) claim that distinctive feature and distinctive trait judgments both lead to the isolation of distinctive features. However, it was argued that distinctive expression judgments led to configural processing that was disrupted by inversion. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Human head-free gaze saccades to targets flashed before gaze-pursuit are spatially accurate

Previous studies have shown that accurate saccades can be generated, in the dark, that compensate for movements of the visual axis that result from movements of either the eyes alone or the head alone that intervene between target presentation and saccade onset. We have carried out experiments with human subjects to test whether gaze saccades (gaze = eye-in-space = eye-in-head + head-in-space) can be generated that compensate for smooth pursuit movements of gaze that intervene between target onset and gaze-saccade onset. In both head-unrestrained (head-free) and -restrained (head-fixed) conditions, subjects were asked to make gaze shifts, in the dark, to the remembered location of a briefly flashed target. On most trials, during the memory period, the subjects carried out intervening head-free gaze pursuit or head-fixed ocular pursuit along the horizontal meridian. On the remaining (control) trials, subjects did not carry out intervening pursuit movements during the memory period; this was the classical memory-guided saccade task. We found that the subjects accurately compensated for intervening movements of the visual axis in both the head-free and head-fixed conditions. We conclude that the human gaze-motor system is able to monitor on-line changes in gaze position and add them to initial retinal error, to program spatially accurate gaze saccades.     

Task dependent variations of ocular lateropulsion in Wallenberg''s syndrome

The eye movements of a patient with a left lateral medullary infarct (Wallenberg's syndrome) were recorded using the scleral search coil in magnetic field technique. When asked to look at spontaneously appearing targets, saccades to the left were generally accurate but those to the right reached the target by multiple step refixation saccades. Large amplitude rightward saccades were possible between two continuously visible targets or when making voluntary saccades in the dark. Vertical saccades, up or down, between spontaneously appearing targets were always associated with a leftward eye movement (lateropulsion). Voluntary vertical saccades between continuously visible targets showed that upward movements had left lateropulsion but downward movements were normal. Vertical voluntary saccades in the dark were oblique, upward saccades showing left lateropulsion and downward saccades rightward deviation. The aberrant horizontal components of normal oblique saccades. Possibly impaired assessment of verticality with incorrect eye position information produced by the infarct accounts for the lateropulsion in saccades in Wallenberg's syndrome.