Presentations

Abstract

Infant-directed songs are rhythmic with exaggerated intonation. These properties promote word segmentation from speech (Jusczyk et al 1999, Johnson & Jusczyk 2001, Mannel & Friederici 2013). Does that mean that infants are particularly good in segmenting words from songs? We measured EEG while we exposed forty 10-month-old Dutch infants to songs and stories, in each of which a word was repeated across phrases. Segmentation of the repeated word was inferred from the ERP familiarity effect (Kooijman et al 2005, Junge et al 2014), comparing the last two presentations to the first two presentations of the repeated word. Contrary to earlier work investigating speech only (Junge et al 2014), in our data there was no significant ERP familiarity effect within the speech condition, suggesting our infants did not segment the words from speech. However, in the song condition we identified a positive shift in the ERP, 300-900 ms after onset of the repeated word, over left frontal electrodes (p<.05 corrected for multiple comparisons). This suggests that the infants are able to segment words from song. Our failure to identify segmentation from speech might be due to the fact that our speech material was less child-directed than in the study of Junge and colleagues (see Floccia et al 2016). Our results suggest that the brain of 10-month-old infants uses the rhythmic and melodic properties of song to detect salient events and to segment words from the continuous auditory input.

Abstract

IIn spoken utterances important or new information is
often linguistically marked, for instance by prosody
or syntax. Such highlighting prevents listeners from
skipping over relevant information. Linguistic cues like
pitch accents lead to a more elaborate processing of
important information (Wang et al., 2011). In a recent
fMRI study, Kristensen et al. (2013) have shown that the
neurobiological signature of pitch accents is linked to the
domain-general attention network. This network includes
the superior and inferior parietal cortex. It is an open
question whether non-prosodic markers of focus (i.e. the
important/new information) function similarly on the
neurobiological level, that is by recruiting the domaingeneral
attention network. This study tried to address
this question by testing a syntactic marker of focus. The
present fMRI study investigates the processing of it-clefts,
which highlight important information syntactically,
and compares it to the processing of pitch accents, which
highlight information prosodically. We further test if
both linguistic focusing devices recruit domain-general
attention mechanisms. In the language task, participants
listened to short stories like “In the beginning of February
the final exam period was approaching. The student did
not read the lecture notes”. In the last sentence of each
story, the new information was focused either by a pitch
accent as in “He borrowed the BOOK from the library”
or by an it-cleft like “It was the book that he borrowed
from the library”. Pitch accents were pronounced without
exaggerated acoustic emphasis. Two control conditions
were included: (i) sentences with fronted focus like “The
book he borrowed from the library”, to account for word
order differences between sentences with clefts and
accents, and (ii) sentences without prosodic emphasis
like ”He borrowed the book from the library”. In the
attentional localizer task (adopted from Kristensen et al., 2013), participants listened to tones in a dichotic
listening paradigm. A cue tone was presented in one ear
and participants responded to a target tone presented
either in the same or the other ear. In line with Kristensen
et al. (2013), we found that in the localizer task cue
tones activated the right inferior parietal cortex and the
precuneus, and we found additional activations in the
right superior temporal gyrus. In the language task,
sentences with it- clefts elicited larger activations in the
left and right superior temporal gyrus as compared to
control sentences with fronted focus. For the contrast
between sentences with pitch accent vs. without pitch
accent we observed activation in the inferior parietal
lobe, this activation did however not survive multiple
comparisons correction. In sum, our findings show that
syntactic focusing constructions like it-clefts recruit
the superior temporal gyri, similarly to cue tones in
the localizer task. Highlighting focus by pitch accent
activated the parietal cortex in areas overlapping with
those reported by Kristensen et al. and with those we
found for cue tones in the localizer task. Our study
provides novel evidence that prosodic and syntactic
focusing devices likely have a distinct neurobiological
signature in spoken language comprehension.