Neuroscience Letters 494 (2011) 250–254 Contents lists available at ScienceDirect Neuroscience Letters journal homepage: www.elsevier.com/locate/neulet Word frequency modulates the processing of emotional words: Convergent behavioral and electrophysiological data Constantino Méndez-Bértolo ∗ , Miguel A. Pozo, José A. Hinojosa Instituto Pluridisciplinar, Universidad Complutense de Madrid, 28040 Madrid, Spain article info Article history: Received 24 September 2010 Received in revised form 7 March 2011 Accepted 7 March 2011 Keywords: Word frequency Emotion Event-related potentials (ERPs) P450 abstract The processing of high frequency (HF) words is speeded as compared to the processing of low frequency (LF) words, which is known as the word frequency effect. This effect has been suggested to occur at either a lexical access or in a decision processing stage. Previous work has shown that word frequency influenced the processing of emotional content at both neural and behavioral levels. However, the results of these studies lead to discrepant findings because some of the variables that have shown to impact the processing of affective information were not always controlled. In order to make a better characterization of frequency effects on emotional word processing, event related potentials (ERPs) and reaction times to HF and LF negative and neutral nouns were measured as participants performed a lexical decision task. Temporal and spatial component analyses were used to detect and quantify, in a reliable way, those components associated with the interaction between word frequency and emotion. LF negative nouns were recognized faster and more accurately than LF neutral nouns whereas no differences were found in the HF word comparison. Also, LF neutral words elicited reduced amplitudes in a late positive component (P450) as compared to LF negative words. These findings might be reflecting a different involvement of attentional mechanisms during the evaluation of lexical information that benefits the processing of LF negative nouns. © 2011 Elsevier Ireland Ltd. All rights reserved. Research on affective neuroscience has shown that the emotional content of words modulates behavioral and electrophysiological measures in lexical decision tasks (LDTs). Participants discriminate words from nonwords faster when they have emotional content [13,17]. The processing of emotional words is associated with enhanced amplitudes of two event-related potential (ERP) compo- nents: an early posterior negativity (EPN), which index effortless initial phases of visual attention [12,27] and a late posterior positivity (LPP) that reflects the functional mobilization of atten- tional resources [5,27]. However, the use of different experimental manipulations, as well as the heterogeneous way of controlling linguistic variables such as word frequency, word length or word category, limits the generalization of these findings. One lexical variable that especially affects word processing is their frequency of occurrence. Psycholinguistic research has estab- lished that high-frequency (HF) words are identified faster than low-frequency (LF) words [20]. Two hypotheses about the locus of the word frequency effects have been proposed [26]. According to the “encoding hypothesis”, word frequency effects are thought to reflect the preattentive access to the lexical representation of words [28,30]. In support of this view, greater amplitudes for LF as ∗ Corresponding author. Tel.: +34 91 394 32 61; fax: +34 91 394 32 64. E-mail address: cmendezbertolo@gmail.com (C. Méndez-Bértolo). compared to HF words have been found in early latency ERP com- ponents such as the N1 or the P1, which are associated with early lexical processing [11,30]. In contrast, the “decision hypothesis”, localizes word frequency effects in decision operations that require limited capacity resources. In particular, LF words require more processing capacity for their evaluation than HF words [2,3,26]. The finding of a differential amplitude modulation by LF and HF words in late latency components, such as the N400 and/or the P300/LPP [11,26], is in agreement with this proposal. These components have been linked to controlled post-lexical and attentional processing, respectively [19,24; but see 15]. The following question arises: do word frequency effects differ- entially modulate the processing of emotional and neutral words? Three previous studies investigated this question. In an fMRI study, Nakic et al. [21] presented high negative, low negative and neu- tral words that were either HF or LF words in a LDT. Pseudowords were created by modifying one letter from the target words. No interaction between emotion and word frequency was observed in reaction times (RTs). However, they found that the processing of HF negative as compared to HF neutral words was associated with decreased activity in the inferior frontal gyrus. Kuchinke et al. [18] measured pupillary and behavioral responses to HF and LF negative, positive and neutral words in a LDT. Interactive effects were only evident in RTs. Both positive and negative LF words were discrim- inated faster than LF neutral words. Also, participants recognized 0304-3940/$ – see front matter © 2011 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.neulet.2011.03.026