The name is absent

FRANCK RAMUS

Minutes

Control group —⅛— Experimental group

Figure 2. Exp. 2: Dutch-Japanese discrimination - Saltanaj
speech, first shift. Minutes are numbered from the shift, indicated
by the vertical line. Error bars represent ±1 standard error of the
mean. Adapted with permission from Ramus et al. (2000). Copy-
right 2000 American Association for the Advancement of Science.

Nevertheless, a discrimination index I was computed ac-
cording to the following formula (Hesketh et al., 1997):

I = post22eχpe - pre2eχpe) - (post2_amt - pre2_amt)

where post2 and pre2 refer to the average number of sucks
during the 2 post-shift (respectively pre-shift) minutes, and
where the cont and expe indices refer to the type of shift
(control or experimental). Thus, a baby increasing her sucks
more to the language shift than to a speaker shift will have a
strictly positive I. Figure 3 gives the values of I for the 11
babies. Table 1 shows the dishabituation scores depending
on type and order of the shifts.

Table 1

Dishabituation scores (post2— pre2) according to order and
type of the shift. The number of observations per case is
indicated in parentheses.

There is a very slight trend in the predicted direction: ba-
bies increase their sucking more during experimental shifts
than during the corresponding control ones. However, this
is true of 6 babies out of 11 only, and the average discrim-
ination index is 1.9 ± 14, not significantly different from 0
[t( 10) < 1].

Note that during the first shift, these 11 babies are behav-
ing consistently with the others during the first shift: they
increased their sucking more (+6.6) to the language change
than to the speaker change (+0). Thus, whereas the first shift
reveals meaningful information concerning the reactions of
infants, the second shift merely shows a perseveration of the

Figure 3. Exp. 2: Values of index I for 11 babies passing the two
shifts.

behavior produced during the first shift, which is little mod-
ulated by the nature of the second shift. In summary, this
attempt suggests that there is little to learn from a second
shift with newborns. However, this outcome does not dimin-
ish the results obtained on the first one, which are clear and
interpretable.

Discussion

The data obtained on the 32 newborns who successfully
passed the first shift show that (a) they are able to discrimi-
nate between Dutch and Japanese, (b) they can do so when
sentences are resynthesized in the saltanaj manner, i.e. when
lexical, syntactic, phonetic and most phonotactic information
is removed..

Although the interaction with Exp. 1 is not quite signifi-
cant [F(1,59) = 2.6, p = 0.11]⁹, this is also consistent with
the hypothesis that newborns have difficulties coping with
talker variability (Jusczyk et al., 1992), which would be the
reason why they failed to discriminate the same sentences
when they were not resynthesized.

The saltanaj resynthesis achieves a comparable level of
stimulus degradation as low-pass filtering: Since all the du-
rations and the fundamental frequency are faithfully repro-
duced, prosody, in a broad sense, is still preserved. It is

⁹ Note that interaction are seldom significant in experiments on
newborns anyway, due to their low statistical power. For instance,
in directly comparable studies, no significant interaction were ever
reported (Mehler et al., 1988; Nazzi et al., 1998).

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