Emotion is characterised by two-dimensions: emotional valence
describes the extent to which an emotion is positive or negative, and
arousal represents its intensity. Emotional content of verbal material
affects cognitive processing, although research on word recognition has
only recently taken emotion into account, primarily focusing on valence,
while neglecting arousal.
The present work aimed to disentangle the effects of valence and
arousal during a lexical decision task, using reaction times (RTs), event-related
potentials (ERPs) and BOLD responses in an event-related fMRI
design. These methods were chosen to determine when affective
features have an effect, and which neural systems are involved.
The material for three experiments was based on a word corpus
created by collecting ratings for emotional and lexico-semantic
features. A first and novel finding was that arousal interacted with
valence. Specifically, lexical decision times were slower for high-arousal
positive stimuli (PH) and low-arousal negative ones (NL) compared to
low-arousal positive (PL) and high arousal negative (NH) stimuli.
ERPs also showed an interaction between 200-300 ms on the early
posterior negativity (EPN), a component which is sensitive to emotional
stimuli. At this processing stage people access their mental lexicon. Its
amplitude was greater for PH and NL words, suggesting a higher
processing load for conflicting stimuli. Positive valence and low arousal
elicit an approach schema, whereas negative valence and high arousal
elicit an avoidance schema (Robinson, Storbeck, Meier & Kirkeby, 2004).
BOLD responses showed a similar interaction in the insula
bilaterally, with increased activation for PH and NL words. This region is
associated with integration of information on visceral states with
higher-order cognitive and emotional processing, suggesting higher
difficulty in integrating conflicting stimuli.
Taken together, these studies indicate that emotion affects word
processing during lexical access, and models of word recognition need
to take into account both valence and arousal
