Testing emotion-inducing visual stimuli
Chemoreception: service dogs demonstrate the existence of an « epileptic seizure odour »
We have tested the reactions of dolphins, dogs and newborns to significant chemosensory stimuli. We could demonstrate for the first time that dolphins do have both an olfactory and a gustatory sense, that allow them to discriminate different quality of resources and that human newborns, even when born prematurely, are able to discriminate their mother’s from other women’s body odours even when sampled outside the classical breast area.
Trained dogs are able to discriminate human body odours sampled during epileptic seizures from those of the same persons outside seizures. This finding is the first evidence that there is an olfactory signature of epileptic seizures independently of both the person and the type of seizure.
Ontogeny has important consequences on the short and long term development of perception and related emotional processing
Ontogeny appears as a major feature in the development of perceptual abilities, and especially of the “meaning” of stimuli.
Hand-raised starlings react with fear to all sorts of visual stimulations, whereas wild starlings caught as adults (normal ontogeny), react by an increased attention and very limited fear reactions to harmless visual stimuli.
In humans, standardized measures of tactile sensitivity (von Frey filaments) have revealed that newborns, and especially those born prematurely, react to much thinner filaments than adults (Coll. Team 3, GIS CCS). The tactile modality, like other sensory modalities, becomes narrower with age, as a result probably of brain maturation and the development of inhibitory circuits, allowing to neglect useless information.
Developmental disorders such as autism are associated with unusual reactions towards visual artificial stimuli (more interest for angles), but also colour preferences (for green) which impact attentional biases for features of interest (e.g. snake versus flowers).
Perception and attention are interrelated
In a series of experiments in monkeys, starlings and horses, we found that attention-getting stimuli (unfamiliar auditory/visual stimuli, individual-specific signals) were associated with an increased activity in the right brain hemisphere (RH) recorded through behavioural (head-turning in Campbell monkeys) and electrophysiological recordings of brain activity (in starlings and horses). The presence of a distractor or anaesthesia can modify the asymmetry pattern. Taken together, these experiments have led us to propose an attention-based model of brain lateralization where attention-getting when stimuli are of high interest or novel, may stimulate RH processing, supporting the idea that attention is at the core of perceptual lateralization.