Ž . Cognitive Brain Research 7 1998 159–163 Research report Modulation of human auditory information processing by emotional visual stimuli Veikko Surakka a, ) , Mirja Tenhunen-Eskelinen b , Jari K. Hietanen a , Mikko Sams a,c a UniÕersity of Tampere, Department of Psychology, P.O. Box 607, FIN-33101 Tampere, Finland b Tampere UniÕersity Hospital, Department of Neurophysiology, P.O. Box 2000, FIN-33521 Tampere, Finland c Laboratory of Computational Engineering, HUT, PO Box 9400, FIN-02015 Hut, Finland Accepted 12 May 1998 Abstract Ž . Auditory event-related potentials mismatch negativity MMN and N100 were recorded from seven subjects while they read text and watched emotionally negative, neutral, and positive pictures varying in valence and arousal. The MMN reflects automatic detection of change in auditory stimulus stream. Functionally different N100 is triggered by onset of various auditory stimuli. The N100 was stabile during all visual conditions. The MMN was very similar during text reading, and neutral and negative slide viewing, but was significantly attenuated during viewing of positively valenced slides. We suggest that visual emotional information of high positive valence and low arousal is a signal of nonthreatening and nonappetitive environment. This kind of environment probably reduces the need for auditory change detection. q 1998 Elsevier Science B.V. All rights reserved. Keywords: Emotion; Mismatch negativity; Arousal; Attention; Amygdala; Evoked potentials 1. Introduction Emotional responses have evolved because they are w x vital for survival and adaptation in environment 9,13 . It has been suggested that the processing of emotionally significant information and reacting to it can be automatic w x and precede conscious perception 20 . LeDoux has sug- gested that there are two basic modes of information w x processing: cognitive and affective 12 . There is also evidence that automatic generation of an affect precedes w x and molds cognitive processing 16,25 . Ž . Event-related potentials ERPs offer one way to study the effects of emotions on early sensory processing in humans. Previous studies have dealt with P3, P4, and late w x slow waves 8,23 . There are two well established mea- sures of relatively early auditory processing. N100 deflec- tion peaks at about 100 ms from the stimulus onset. The neurons underlying N100 are suggested to be capable of detecting the stimulus on-roffset and act as an internal w x attention trigger 17 . On the other hand, functionally Ž . different mismatch negativity MMN , peaking at 100–300 ms from the stimulus onset reflects a deviance in any ) Corresponding author. Fax: q358-3-215-7710; E-mail: psvesu@uta.fi w x constant feature of repetitive auditory stimuli 14,17–19 . The MMN is automatic in a sense that it is elicited by w x changes in unattended stimuli 17,19 . The present aim was to study if visual emotional infor- mation affects basic auditory information processing as measured with the N100 and the MMN. ERPs to standard and deviant tones were recorded while the subjects read a text and watched visual stimuli differing in valence and arousal. We hypothesized that if emotional stimuli affect early auditory processing, it should be reflected in the amplitudes of the N100 andror the MMN. 2. Subjects, materials, and methods Eleven volunteer psychology students participated in the study. The data from four subjects had to be discarded because of excessive artifacts or lack of the MMN in the Ž reading phase. Therefore, data from seven subjects three . males and four females were used in the final analyses. The auditory stimulus sequence consisted of frequent Ž . Ž . standard 1000 Hz and infrequent deviant 1050 Hz tones Ž . presented to the left ear via eartube at the probabilities of 0.85 and 0.15, respectively. At least 2 standard sounds 0926-6410r98r$ - see front matter q 1998 Elsevier Science B.V. All rights reserved. Ž . PII: S0926-6410 98 00021-4