I’ve always had a deep interest in syntactic topics like clause structure and A-bar movement. My masters thesis was an analysis of clause structure in Chukchansi Yokuts, the result of fieldwork with the last surviving native speakers. My first ever ERP project looked at working memory resources reflected in sustained anterior negativity (SAN) in long distance dependencies. Below are some ERP projects related to sentence processing I have collaborated on.
Computing the Timecourse of Negation
People generally find it quite easy to construct and understand a negated sentence such as This car is not a Ford. We utter sentences like this many times a day. Yet exactly how negation is processed is a matter of debate. When we hear a sentence like This car is not a Ford, do we compute the meaning of the structure one word at a time in the exact order the words appear? Or do we compute the meaning of the inner proposition first – This car is a Ford – and then, as a second step, negate this proposition?
Previous studies have found that negated sentences are generally processed in two steps – unless the negation appears in a pragmatically licensed context. Think With proper equipment, scuba diving is not… The continuation of the sentence is very predictable, given the negation. This contrasts with studies that find two-step processing, where the brain seems to ignore the negation entirely when predicting sentence continuations!
Working with Bilge Palaz at the University of Delaware, we used ERPs to detect whether participants computed negation incrementally (whether negation would influence predictions about sentence continuation) or in a two-step process. We were interested in whether another kind of pragmatic licensing was relevant for this computation – informativity. In the real world, we expect utterances to be informative, which might explain why sentences like A hammer is not a bird elicit surprise responses. They’re not sentences that any of us are likely to ever hear!
We replicated the design of previous ERP studies on negation, with the addition of pseudowords presented in a fast-mapping rapid word learning context. Participants guessed the meanings of the pseudowords from a context sentence, then read a target sentence containing negation. These target sentences (ex: A crilge is not a plant) are informative, because participants can’t be completely certain of the meanings of these novel words.
Despite the addition of informativeness, we find the exact same negation-blind pattern of ERPs as previous studies. This indicates that negation in these sentences is computed in a two-step process. While negation can affect lexical expectations in the presence of pragmatic licensing, it seems that this is not true of informative contexts!
This study was published in Psychophysiology in September 2020: https://doi.org/10.1111/psyp.13676
Island Constraint and Reanalysis in Mandarin Topic Structure
There is some debate in the literature about whether Mandarin topic constructions are movement-derived or base-generated. Behavioral studies have found conflicting evidence for and against the observation of island constraints in Mandarin. Working with Renee Dong at the University of Delaware, we used ERPs to investigate the parser’s sensitivity to island constraints in Mandarin and weigh in on this debate.
We use the filler-gap paradigm of Traxler & Pickering (1996) to elicit ERPs in Mandarin filler-gap topic constructions. We manipulate the plausibility of the filler and the presence or absence of syntactic islands. We predicted an N400 at the critical verb in the non-island conditions, as well as an ELAN/P600 complex at the actual object.
Although we find no N400, we do see anterior negativity at the verb and a P600 at the object in non-island relative to island conditions. We interpret the P600 as a ‘semantic P600’ in response to the plausibility manipulation, which involves an animacy violation.
The presence of the P600 in the non-island conditions indicates active gap-filling and reanalysis in these constructions. The absence of P600 in the island conditions indicates an observance of island constraints – evidence for the movement account of Mandarin topic structure!
