Factors Influencing Manual Discrimination of Orientations in 5-Month-Old Infants

Influence of visual contextual cues on haptic discrimination of orientations in 5-month-old infants

The present research addressed the question of the influence of visual contextual cues on the manual discrimination of spatial orientations in 5-month-old infants. Different types of visual contextual cues were proposed during the haptic discrimination task: congruent-informative, non congruent-informative or noninformative. A familiarization (with a 60-s fixed-duration)/reaction to novelty procedure was used in three experiments. In Experiment 1, a congruent-informative visual context (a visual context composed of alternate black and white stripes tilted to 20 degrees -left) was present and a haptic discrimination between a 20 degrees -left rod and a 30 degrees -left rod was observed (this discrimination was absent without visual context in Gentaz and Streri's study, 2004). In Experiment 2, the visual context cues (composed of black dots) were noninformative, and infants could not discriminate these two oblique rods. In Experiment 3, the presence of a non congruent visual context (a visual context composed of alternate black and white stripes tilted to 20 degrees -left, as in Experiment 1) disturbed the gravitational vertical perception usually observed: infants could not discriminate the vertical rod from the 10 degrees -left rod. These results showed that only the informative (congruent and non congruent) visual contextual cues influenced the haptic discrimination of spatial orientations in 5-month-old infants. These results are discussed in relation with data observed in adults and with the current models of the multisensorial integration and attentional level.

The haptic perception of spatial orientations

This review examines the isotropy of the perception of spatial orientations in the haptic system. It shows the existence of an oblique effect (i.e., a better perception of vertical and horizontal orientations than oblique orientations) in a spatial plane intrinsic to the haptic system, determined by the gravitational cues and the cognitive resources and defined in a subjective frame of reference. Similar results are observed from infancy to adulthood. In 3D space, the haptic processing of orientations is also anisotropic and seems to use both egocentric and allocentric cues. Taken together, these results revealed that the haptic oblique effect occurs when the sensory motor traces associated with exploratory movement are represented more abstractly at a cognitive level.