The brain, verbs, and the past: Neurolinguistic studies on time reference

The sentence ‘de man biked’ is more difficult than ‘the man is biking’ for people with agrammatic aphasia. Agrammatic aphasia is a grammatical disorder caused by brain damage such as stroke. In Dutch/English, one can paradoxically refer to the past by means of a verb form in present (perfect) tense, for example ‘has biked’. Laura Bos shows that it is not the past tense per se that is difficult, but reference to the past irrespective of the verb form employed: For Dutch people with aphasia, it was more difficult to complete sentences with the simple past or present perfect than with the simple present. According to Bastiaanse and colleagues (2011), this is because for reference to the past, one refers to an event before the moment of speech. This event should be recalled from discourse, which requires additional brain capacity. This discourse-explanation is supported by another study of this PhD research: Russian people with aphasia had a simultaneous impairment in comprehension of discourse-processes, including time reference. Also healthy people made this discourse-related distinction in time reference, as shown in a third study involving brain activity measurements using electroencephalography. In a fourth study, Laura Bos has analysed eye movements. These showed that German agrammatic aphasic participants were equally fast as healthy participants in processing verb forms referring to the future, but slower in processing verb forms referring to the past. These results together form another small piece in the big puzzle of language processing.