In order to test the solidity of the links between the sensory modalities during the second semester of life, the most frequently manipulated variable is that of the familiarization duration. Thus, touch-vision (T-V) intermodal transfers concerning object substance reveal an improvement in the speed of the treatment of haptic information between the ages of 1 and 12 months. WalkerAndrews and Gibson (1986) showed that the six-month-old baby does not recognize the substance (hardness) of an object manipulated after twenty seconds of familiarization, whereas at 12 months s/he does. The development of the intermodal transfer of object shape during the second semester confirms the complexity of the results obtained in very young babies and insists on the highly cognitive character of this form of relation between the two modalities. For example, Ruff and Kohler (1978) obtained a touch-vision transfer (T-V) in six-month-olds after a thirty-second manual familiarization period with simple objects like a sphere and a cube. On the other hand, at the same age, Rose et al. (1981a) tested three T-V transfer tasks with more complex objects explored either orally (1 test) or manually (2 tests). The tactile familiarization duration phase was also 30 seconds. The six-month-old babies failed to visually recognize the sucked or palpated objects. This failure, attributable to the short duration of haptic familiarization, is also linked to the complexity of the objects. If the babies explore the objects for sixty seconds visual recognition is observed after manual exploration, but not after oral exploration. The three transfer tasks are successfully completed only at about the age of twelve months (Gottfried, Rose, & Bridger 1977). At the same age, however, the reverse transfer - from vision to touch (V-T) - is not obtained after 30 seconds of familiarization but is obtained after sixty seconds in a two-minute tactile test (Rose, Gottfried, & Bridger 1981b). This research once again brings up the question as to the non-reversibility of transfers. The question was re-examined by Rose and Orlian (1991), who compared intramodal visual (V-V) and tactile (T-T) performances with intermodal V-T and T-V tasks in twelve-month-olds. The familiarization phases lasted fifteen, thirty or sixty seconds according to groups. The results revealed that the V-V condition is the easiest, whatever the duration of familiarization. The T-T and T-V conditions are intermediate since recognition is obtained after thirty and sixty seconds, but not after fifteen seconds of familiarization. However, the babies fail to tactually recognize objects already looked at, whatever the duration of the familiarization period. These results recall those found with two-month-old babies, but Rose and Orlian (1991) offer another interpretation and explain the V-T transfer failure as attributable to a difference in the information gathered on the characteristics of the objects by the two modalities (cf. Rose 1994). However, after 45 seconds of familiarization 12-month-old babies can visually recognize in a photo or a sketch an object they have previously held (Rose, Gottfried, & Bridger 1983). The transfer between the two modalities is thus based on the abstraction of the contour of the objects, which is invariant.
With different paradigms Bushnell and Weinberg (1987) showed that eleven-month-old babies are sensitive to the difference between a smooth egg and a furry cube on the one hand, and a smooth cross and a furry cube on the other hand. However, the babies do not react to the presentation of the cube and the smooth cross whereas they make the difference between the cube and the smooth egg. Intermodal matching is thus easier when the objects differ in more than one dimension (shape + texture). The fact that babies fail to discriminate between the cube and the cross suggests that they are not yet very sensitive to linear breaks in shape, thus confirming the oldest Bryant, Jones, Claxton and Perkins (1972) intermodal transfer study. Conflict situations are an interesting way of testing the degree of integration of the two systems. Bushnell (1982) put 8,9 V and 11-month-old babies in a situation in which they saw an object different from the one they manipulated. An integration of visual and tactile space is obtained only from the age of nine months, thus confirming the weakness of transfers before this age.
This weakness also appears in studies examining the risks linked to populations of children presenting mental handicaps, neuronal damage or learning difficulties (cf. Freides 1974). Rose, Gottfried and Bridger (1978) studied the influence of social and biological factors on intermodal transfer in twelve-month-old babies born prematurely (at birth the gestational age was 32.6 weeks, the weight was 1650g) and full term twelve-month-olds, from a low socio-economic class. The authors re-used the three transfer tasks already mentioned, for a 30-second period of haptic familiarization. No intermodal transfer was obtained, contrary to experiments carried out on babies of the same age but from a middle socio-economic class. These experiments were repeated on baby monkeys (macaca nemestrina) by Gunderson, Rose and Grant-Webster (1990). The baby monkeys were aged 13.5 weeks on average at the time of the experiment (biological maturation was thus comparable to that of twelve-month-old human babies). Twelve were regarded as capable of normal development from a cognitive point of view, whereas 15 were classed as "high-risk" due to their light birth weight, difficult development, a traumatic birth, or pre-natal exposition to ethanol. The babies were orally and manually familiarized with objects for thirty seconds, then the visual recognition task lasted twenty seconds. The monkeys which presented deficits failed the visual recognition test, whereas those born normally succeeded. This similarity in performance with human babies suggests that processes underlying intermodal transfers are shared by different species (cf. Lewkowicz 2000; Lewkow-icz & Lickliter 1994). But the fact that intermodal transfer is sensible to clinical factors or depends on the speed of treatment of information casts a doubt on its stability in older children.
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Once your pregnancy is over and done with, your baby is happily in your arms, and youre headed back home from the hospital, youll begin to realize that things have only just begun. Over the next few days, weeks, and months, youre going to increasingly notice that your entire life has changed in more ways than you could ever imagine.