Emanuela Bricolo

My eyes want to look where your eyes are looking: exploring the tendency to imitate another individual's gaze.

In this study we investigated the tendency of humans to imitate the gaze direction of other individuals. Distracting gaze stimuli or non biological directional cues (arrows) were presented to observers performing an instructed saccadic eye movement task. Eye movement recordings showed that observers performed less accurately when the distracting gaze and the instructed saccade had opposite directions, with a substantial number of saccades matching the direction of the distracting gaze. Static (Experiment 1) and dynamic (Experiment 2) gaze distracters, but not pointing arrows (Experiment 3), produced the effect. Results show a strong predisposition of humans to imitate somebody elses oculomotor behaviour, even when detrimental to task performance. This is likely linked to a strong tendency to share attentional states of other individuals, known as joint attention.

Do all kids look alike? Evidence for an other-age effect in adults

The current study provides evidence for the existence of an other-age effect (OAE), analogous to the well-documented other-race effect. Experiments 1 and 2 demonstrate that adults are better at recognizing adult faces compared with faces of newborns and children. Results from Experiment 3 indicate that the OAE obtained with child faces can be modulated by experience. Moreover, in each of the 3 experiments, differences in the magnitude of the observed face inversion effect for each age class of faces were taken to reflect a difference in the processing strategies used to recognize the faces of each age. Evidence from Experiment 3 indicates that these strategies can be tuned by experience. The data are discussed with reference to an experience-based framework for face recognition.

Holistic processing for faces and cars in preschool-aged children and adults: Evidence from the composite effect

The current study compared the development of holistic processing for faces and non-face visual objects by testing for the composite effect for faces and frontal images of cars in 3- to 5-year-old children and adults in a series of four experiments using a two-alternative forced-choice recognition task. Results showed that a composite effect for faces was present as early as 3 1/2 years, and none of the age groups tested showed signs of a composite effect for cars. These findings provide the first demonstration that holistic processing is already selective for faces in early childhood, and confirm existing evidence that sensitivity to holistic information in faces does not increase from 4 years to adulthood.

Perseveration in left spatial neglect: drawing and cancellation tasks

Perseveration in target cancellation tasks and in drawing by copy and from memory was investigated in 21 right-brain-damaged patients, seven with no evidence of left visuo-spatial neglect, and 14 with neglect. Eight such neglect patients showed perseveration in both cancellation and drawing tasks, although no correlation was found with the severity of neglect. Patients with perseveration were not disproportionately impaired in tasks assessing executive (fluency, Stroop colour-word interference, and Weigls sorting test), and visuo-spatial short-term memory function. In the context of a two-component hypothesis, graphic perseveration (the first component) is a specific disorder that manifests in a variety of tasks, particularly those requiring serial graphic production. Unilateral spatial neglect (the second component) may trigger and facilitate the production of perseveration errors, with a contra-ipsilateral gradient of increasing severity.

The representational space of numerical magnitude: illusions of length.

In recent years, a growing amount of evidence concerning the relationships between numerical and spatial representations has been interpreted, by and large, in favour of the mental number line hypothesis—namely, the analogue continuum where numbers are spatially represented (Dehaene, 1992; Dehaene, Piazza, Pinel, & Cohen, 2003). This numerical representation is considered the core of number meaning and, accordingly, needs to be accessed whenever numbers are semantically processed. The present study explored, by means of a length reproduction task, whether besides the activation of lateralized spatial codes, numerical processing modulates the mental representation of a horizontal spatial extension. Mis-estimations of length induced by Arabic numbers are interpreted in terms of a cognitive illusion, according to which the elaboration of magnitude information brings about an expansion or compression of the mental representation of spatial extension. These results support the hypothesis that visuo-spatial resources are involved in the representation of numerical magnitude.

Serial Attention Mechanisms in Visual Search: A Direct Behavioral Demonstration

In visual search, inefficient performance of human observers is typically characterized by a steady increase in reaction time with the number of array elementsthe so-called set-size effect. In general, set-size effects are taken to indicate that processing of the array elements depends on limited-capacity resources, that is, it involves attention. Contrasting theories have been proposed to account for this attentional involvement, however. While some theories have attributed set-size effects to the intervention of serial attention mechanisms, others have explained set-size effects in terms of parallel, competitive architectures. Conclusive evidence in favor of one or the other notion is still lacking. Especially in view of the wide use of visual search paradigms to explore the functional neuroanatomy of attentional mechanisms in the primate brain, it becomes essential that the nature of the attentional involvement in these paradigms be clearly defined at the behavioral level. Here we report a series of experiments showing that highly inefficient search indeed recruits serial attention deployment to the individual array elements. In addition, we describe a number of behavioral signatures of serial attention in visual search that can be used in future investigations to attest a similar involvement of serial attention in other search paradigms. We claim that only after having recognized these signatures can one be confident that truly serial mechanisms are engaged in a given visual search task, thus making it amenable for exploring the functional neuro-anatomy underlying its performance.

Cerebral Correlates of Visuospatial Neglect: A Direct Cerebral Stimulation Study

To assess the role of the superior longitudinal fascicle, the inferior fronto‐occipital fascicle, and the posterior parietal lobe in visuospatial attention in humans during awake brain surgery.

Is audiovisual integration subserved by the superior colliculus in humans

The brain effectively integrates multisensory information to enhance perception. For example, audiovisual stimuli typically yield faster responses than isolated unimodal ones (redundant signal effect, RSE). Here, we show that the audiovisual RSE is likely subserved by a neural site of integration (neural coactivation), rather than by an independent-channels mechanism such as race models. This neural site is probably the superior colliculus (SC), because an RSE explainable by neural coactivation does not occur with purple or blue stimuli, which are invisible to the SC; such an RSE only occurs for spatially and temporally coincident audiovisual stimuli, in strict adherence with the multisensory responses in the SC of the cat. These data suggest that audiovisual integration in humans occurs very early during sensory processing, in the SC.

TMS modulation of visual and auditory processing in the posterior parietal cortex

Audio-visual stimuli typically yield faster responses than isolated modality-specific ones. This crossmodal speed advantage depends upon efficient multisensory integration mechanisms in the brain. Here, we used repetitive transcranial magnetic stimulation (rTMS) to address the role of the posterior parietal cortex, in particular of the inferior parietal lobule (IPL), in speeding up responses to crossmodal stimuli. The results show that rTMS over IPL impairs the response to contralateral modality-specific visual and auditory targets without affecting the response speed advantage following audio-visual targets. Furthermore, this speed advantage is subserved by a neural coactivation mechanism suggesting a summation in a given neural site. Control rTMS over V1 impaired only contralateral visual responses without affecting the response to auditory or audio-visual targets. These results suggest that the response speed advantage for crossmodal targets is maintained in spite of the IPL interference that impairs modality-specific responses. The possible role of alternative sites for the audio-visual advantage, such as the superior colliculus, is discussed.

Sudden insight is associated with shutting out visual inputs.

Creative ideas seem often to appear when we close our eyes, stare at a blank wall, or gaze out of a window—all signs of shutting out distractions and turning attention inward. Prior research has demonstrated that attention-related brain areas are differently active when people solve problems with sudden insight (the Aha! phenomenon), relative to deliberate, analytic solving. We directly investigated the relationship between attention deployment and problem solving by recording eye movements and blinks, which are overt indicators of attention, as people solved short, visually presented problems. In the preparation period, before problems eventually solved by insight, participants blinked more frequently and longer, and made fewer fixations, than before problems eventually solved by analysis. Immediately prior to solutions, participants blinked longer and looked away from the problem more often when solving by insight than when solving analytically. These phenomena extend prior research with a direct demonstration of dynamic differences in attention as people solve problems with sudden insight versus analytically.