Unconscious detection of verbal and non-verbal ambiguous stimuli
Ambiguity plays an important role in our everyday cognitive
experience. Since the 1980s, the neural bases for the perception of
ambiguous information have been investigated but remains poorly
understood. In our previous research, an increase of the N400 ERP
component was found to be a common response for the perception
of two different types of ambiguous stimuli: “canned” verbal jokes
and ambiguous figures (Shcherbakova, Filippova, 2016; Filippova,
Shcherbakova, Shtyrov, 2018). The current experiment aimed to
understand the relationship between the error related negativity
(ERN) component arising from jokes and ambiguous figures mistaken
for non-humoristic texts and non-ambiguous figures.
Fourteen participants (9 females) went through two similar
experimental procedures with 36 ambiguous and 36 non-ambiguous
figures; 14 verbal jokes and 14 similar but non-humoristic
short stories. Firstly, participants were presented with figures of
both types and asked to identify whether each figure was
ambiguous or non-ambiguous. We recorded ERPs that were timelocked
to each answer about ambiguity/non-ambiguity of the
figure presented. Secondly, participants were presented with the
verbal stories and asked to identify whether each story was a joke
or not. In this case, ERPs were time-locked to each answer about
the key phrase of a joke/non-joke presented word-by-word on the
computer screen after the whole text.
But we found an increase of the ERPs’ negativity in ambiguous
figures that were mistaken for non-ambiguous ones in the ERN
time window (Fz (F(3,622) = 12,6; p b 0.00) and Cz (F(3,625) =
6,96; p b 0.00)). Also, the results revealed no increase of the ERPs’
negativity in verbal jokes that were mistaken for non-jokes in the
ERN time window. The results show that participants appeared to
be sensitive (without awareness) to ambiguous figures that were
identified as non-ambiguous ones. The level of this unconscious
sensitivity is therefore reflected by the increases in negativity.
When a participant cannot correctly identify ambiguous stimulus
at a conscious level, increases in negativity may be indexing greater
violations of incongruence within an internal representation of meaning. These violations may precede semantic reversion of ambiguous figures and the understanding of a joke’s meaning.
Supported by RFBR (Dpt of Humanities and Social Sciences) grant #17-06-01014 А and RFBR grant #18-013-01086.