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@@Developmental Research into Infant Back-Haptic Source Localization

  @@@@@@@@@@ Fumio Kayo( Kyoto University of Education)

                  

Abstract: This research investigates tactile contact to the area of infantsf backs, and its purpose is to elucidate the stage at which the baby will react and turn towards the source when approached from behind, without it's knowing, and touched (back haptic source localization ; BHSL) . Subjects were 48 Japanese infants (6 months -27months). Results showed no signs of BHSL in infants under 1 year old, and it seems reasonable to say that signs of response begin to show between the ages of 1 and 2 years. It seems to express a surprisingly nonchalant nature in human infants.


Main text:
@There has been accumulated research concerning the development of sound source localization, and presently it is a widely accepted view that it becomes, little by little, more sophisticated for new-born infants in their first four months (Muir, et al.,1989; Burnham & Mattok, 2010). How, then, about tactile sense source localization? When does localization occur for touched body areas?

This research investigates tactile contact to the area of infantsf backs, and its purpose is to elucidate the stage at which the baby will react and turn towards the source when approached from behind, without it's knowing, and touched (back haptic source localization; herein : BHSL).

 
Method :

Participants

Participants were 48 infants in nursery school in Kyoto City,  Japan : younger group of 7 males and 4 females, 6 to 12 months of age (average of 9.2 months); middle group of 14 males and 6 females, 14 to 18 months of age (average of 15.6 months); and older group of 10 males and 7 females, 19 to 27 months of age (average of 22.9 months). All infants were developing normally, had no history of serious ill.

Procedure

There were infants who were shy of strangers and in order to maintain a calm atmosphere in the nursery school room, experiment was conducted by the supervising nursery teacher. The teacher was instructed to conduct the test 3 times after confirming the following 4 points:

i.      make sure no-one is to be in front of the child distracting or encouraging him/her

ii.     approach the child from behind, without a word, without his/her noticing

iii.    without causing the child to lean or topple over, slide the palm of the hand up and down  twice on the childfs back

iv.   wait at least one hour between each of the 3 tests

To minimize feelings of excessive pressure for the teacher, instructions concerning the situation and the touching were not overly rigid.  The tests took place indoors through October and November with the children wearing T-shirts .

The childrenfs responses were categorized as below and the teacher was instructed to record each testfs result on a provided coding sheet:

A     turns around immediately

B     turns around after a short pause (2-3 seconds)

C     does not turn around

D     unable to categorize

A space was provided for the teacher to note freely any comments.

Results and Discussion

The fourth category D applied only to one 26 month olds in the first round of tests. Based on the categories A and C, if all of the 3 tests per child resulted in category A, the child was categorized as BHSL-type, and if all of the 3 tests per child resulted in category C, the child was categorized as non-BHSL-type. Mixed, plural results in which a clear type could not be discerned were regarded as a transitional, intermediate stage. Table 1 shows the results.

  @@@@@@@@@Table 1. No. of Children According to Group

Groupiagej

Non-BHSL

Transitional

BHSL

young  (6 to 12 months)

11

0

0

middle (14 to 18 months)

10

7

3

older (19 to 27 months)

0

9

8

 

In the comments provided by the teacher conducting the tests, there were comments for category C such as gdid not turn around, but furrowed his browh, gdid not turn around, but straighten her spineh, or gno reactionh.  For category A, comments such as gsmiledh, gexpression as if to ask, eWhat is that?fh, gscowledh, or gSaid, eDonft!fg.

Overall, results showed no signs of BHSL in infants under 1 year old, and it seems reasonable to say that signs of response begin to show between the ages of 1 and 2 years. It seems to express a surprisingly nonchalant nature in human infants.


References

D.W. Muir, R. K. Clifton, M. G. Clarkson(1989) The development of a human auditory localization response: AU-shaped function. Can. J. Psychol. 43(2), 199-216.

D. Burnham,  K. Mattok(2010) In The Wiley-Blackwell Handbook of Infant Development, G. Bremner,  T.D.   Wachs, Eds. (2nd ed., Wiley-Blackwell), 81-119  

 Acknowledgements:

   The data reported in this paper were presented at The 23rd Annual Meeting of Japan Society of Developmental Psychology, Nagoya, Japan (2012, March).