Active Research Projects
We conduct experiments examining the neural underpinnings of aspects of language and cognitive processing, in typically developing children and adults as well as those exhibiting atypical or pathological development utilizing combinations of behavioral and electrophysiological techniques.
This page provides short summaries of our current and recent research projects. All our work is collaborative; names given here are only the lead lab personnel on each project.
If you would like to participate in any of these studies, please fill in and submit the volunteer form.
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Effects of diglossic codeswitching and semantic coherence in speakers of Modern Arabic (Reem Khamis-Dakwar)
Using EEG, this study is investigating lexical and syntactic processing in codeswitching between two language varieties which exist in a diglossic situation (Modern Standard Arabic (MSA) and Colloquial Palestinian Arabic (PCA)). We present sentences in PCA and MSA: grammatical sentences in the targeted variety, sentences with semantically anomalous final words, sentences with codeswitched final words, and sentences where the final word was both semantically anomalous and code-switched. We ask participants to judge whether the final word is in the same language as the rest of each sentence. Event-related potentials in response to the four conditions in each language variety, and between the two language varieties, showed that differences in N400 amplitude correlated with semantic anomaly in both languages, whereas the codeswitching manipulation resulted in a variety of changes both earlier (ELAN: 100-300 milliseconds post-onset) and later (P600: 500-700 milliseconds post-onset) in the processing stream. We need native speakers of Palestinian Arabic to participate in this study - if you're interested, please fill in the volunteer form (including information about your native language).
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Speech perception in late Spanish-Enlgish bilinguals - an EEG study of vowel recognition (Paula Garcia)
This study examines the perception of the English vowel contrast /i/ vs. /I/ by native Spanish speakers. Speech perception studies have revealed that perception of foreign vowels is influenced by the phoneme categories in the native language. Some native Spanish speakers find it difficult to discriminate /i/ and /I/, and they often report identifying both vowels as a single Spanish vowel. In two auditory oddball paradigms, participants were asked (a) to ignore and (b) to attend to binaurally presented English vowel sounds. Event-related potential analyses revealed a more anterior N100 response to the native than the non-native vowels in the non-attentional condition, though there was no significant amplitude difference between the two (hence, no mismatch negativity effect). This pattern of responses may be consistent with previous research showing that activation of the auditory what stream is involved in analysis of phonological features of the speech stream. In the attentional condition, the P300 showed increased amplitudes in response to the non-native vowels when compared to the native vowels; this amplitude difference was not seen in native English-speaking controls, and may provide an index of allocation of additional attentional resources to a less familiar sound. Our results suggest that there is a process of assimilation at play in L2 perception, by which non-native phonemic contrasts are assimilated to L1 contrasts. This could have implications for pedagogical approaches to second language learning, since phonemic contrasts which cannot be perceived are concomitantly more difficult to acquire.
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An Electroencephalogram Investigation of Two Modes of Reasoning (Chaille Maddox)
The purpose of the proposed study is to investigate the neurophysiology of mental model (MM) and mental rule (MR) reasoning using high-density electroencephalography (EEG), with the goal of providing a characterization of the time course and a general estimate of the spatial dimensions of the brain activations correlated with these specific instances of two classic views of reasoning. The research is motivated by two questions: 1) Will violations of expectancy established by the devised MM and MR reasoning strategies evoke the N400 and P600 ERPs, respectively, and 2) Will topographical scalp distributions associated with each reasoning strategy suggest distinct psychological representations and processes