| Abstract |
Research on infant inter-modal perception (Meltzoff & Borton, 1979, Spelke
& Owsley, 1979) has proved the function of mechanisms such as inter-sensory
coordination of visual and auditory, as well as visual and haptic or kinaesthetic
stimuli. Nowadays, the infant is considered as an organized entity, a person showing
off intentional behaviors and being endowed with inter-modal perceptual abilities,
present even at birth (Kugiumutzakis, 1985, Meltzoff & Moore, 1977).
In the present cross-sectional experimental study 78 infants, aged 5, 7 and 9
months old, boys and girls, attended to 28 pairs of two-dimensional colour pictures of
familiar objects and two persons, one of the mother and another of a stranger woman.
The stimuli in each trial differed in numerosity. In each trial, one, two or three sounds
accompanied the visual stimuli, projected in numerical combinations of 1 - 2, 1 - 3 or
2 - 3 items. In one experimental condition the stimuli were images of identical objects,
while in another experimental condition the stimuli were different objects. In both
conditions, piano sounds were heard. In two other conditions, either objects and the
image of mother’s face or objects and the image of a stranger woman’s face were
projected, respectively accompanied by either musical sounds and the mother’s voice
or by musical sounds and the stranger’s voice.
The assessment of infant’s ability to perceive the numerical correspondences
across visual and auditory stimuli was achieved by measuring the duration of attention
toward the corresponding visual stimulus just after the sound was played. Detection of
visual-auditory numerical correspondences (when for example, the infant, after the 2
sounds, attends to the visual stimulus with the 2 objects) was found to be functioning
at the early age of 5 months, since infants’ micro-analyzed preferential looking proved
the existence of intermodal perception of numercal equivalence. The success in the
particular task varied according to age, gender, and condition, as well as according to
qualitative and quantitative properties of the visual and auditory stimuli. More
specifically, in the present study, the factors that influenced infant’ s performance are:
a) numerical combination of the projected visual stimuli (1-2 / 1-3 / 2-3), b) numerosity of auditory stimuli (1, 2, 3 sounds), c) quality of auditory stimuli (piano
sound, voice of the mother, or voice of a stranger woman) and d) quality of visualauditory
stimuli differentiating across the experimental conditions (e.g. identical
projected visual stimuli - music sounds or different objects - mother’s face and music
sound or mother’s voice).
More specifically, concerning the percentages of intermodal success in the
total of the microanalyzed infant behaviors (3= 1206), success appears at 58%. At the
age of 5 months, infants are able to detect the numerical correspondence between
visual and auditory stimuli, and at the age of 7 and 9 months, one can observe a
relative increase of the appearance of the particular ability. Girls present more
successes than boys do. When images of different objects are projected, and when
musical sounds are heard, in the present intermodal coordination task, it appears that
detection of numerical constancy across the visual-auditory stimuli is hindered.
Moreover, a slight increase of successes is observed in the conditions where the face
and voice are part of the visual and auditory stimuli respectively. It appears, that girls
succeed more often at the conditions with the face and voice, whereas, boys succeed
more often in the condition with identical objects and musical sounds.
As far as the mean time of tendency of intermodal success is concerned, it
appears that in the particular experimental task, duration of infant attention towards
the numerically corresponding to the sound visual stimulus, is affected by the infant
age and gender, as well as by the quality and quantity of visual-auditory stimuli. The
tendency of failure is more intense at the age of 5 months. Boys develop the ability of
intermodal numerical matching at a later stage (7-9 months), than girls do (5 months).
Projection of different visual stimuli hinders the performance of detection of intersensory
numerical matching. Nevertheless, infants seem to be able to discriminate
between “many” and “few” stimuli, by coordinating inter-sensory information. The
face, as more attractive stimulus, appears to abstract infant attention from the
detection of numerical correspondence. It seems that quantitative and qualitative
factors varying across the visual-auditory stimuli, interact, consequently affecting the
infant performance at the particular numerical correspondence coordination task.
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Πειραματική μελέτη της ανάπτυξης του οπτικο-ακουστικού συντονισμού κατά τη βρεφική ηλικία
