In conversation, negative responses to invitations,
requests, offers and the like more often occur with
a delay – conversation analysts talk of them as
dispreferred. Here we examine the contrastive
cognitive load ‘yes’ and ‘no’ responses make,
either when given relatively fast (300 ms) or
delayed (1000 ms). Participants heard minidialogues,
with turns extracted from a spoken
corpus, while having their EEG recorded. We find
that a fast ‘no’ evokes an N400-effect relative to a
fast ‘yes’, however this contrast is not present for
delayed responses. This shows that an immediate
response is expected to be positive – but this
expectation disappears as the response time
lengthens because now in ordinary conversation
the probability of a ‘no’ has increased.
Additionally, however, 'No' responses elicit a late
frontal positivity both when they are fast and when
they are delayed. Thus, regardless of the latency of
response, a ‘no’ response is associated with a late
positivity, since a negative response is always
dispreferred and may require an account. Together
these results show that negative responses to social
actions exact a higher cognitive load, but especially
when least expected, as an immediate response.