The role of valence in word processing: Evidence from lexical decision and emotional Stroop tasks

It is widely accepted that the valence of a word (neutral, positive, or negative) influences lexical processing, yet data from the commonly used lexical decision and emotional Stroop tasks has yielded inconsistent findings regarding the direction of this influence. One critical obstacle to investigating the independent effects of valence is the matching of emotional and neutral stimuli on the lexical, sublexical, and conceptual characteristics known to influence word recognition. The second obstacle is that the cognitive processes which lead to a lexical decision and a colour naming response are unobservable from the response latency measures typically gathered. The present study compiled a set of neutral, positive, and negative words matched triplet-wise on 26 influential characteristics. The novel "mouse tracking" technique was used to analyse the development of responses to these materials in variants of the lexical decision and emotional Stroop task. A conventional key-press emotional Stroop task is also reported. Results revealed a significant processing advantage for positive words over negative and neutral words in the lexical decision task, whereas valence alone did not produce any significant effects in the emotional Stroop task. The discrepancy between the effects of valence across these different tasks is discussed. We also suggest that previous conflicting findings may be confounded by unmatched emotional and neutral stimuli, thus inflating the potential effects of valence.