No Effect of Action on the Tritone Paradox 315 MUSIC NOTATION , BUT NOT ACTION ON A KEYBOARD , INFLUENCES PIANISTS’ JUDGMENTS OF AMBIGUOUS MELODIES BRUNO H. REPP Hommel, Müsseler, Aschersleben, & Prinz, 2001; Proffitt, Haskins Laboratories 2006; Schütz-Bosbach & Prinz, 2007; Wilson & Knoblich, 2005). Almost all of these studies have been concerned ROBERT M. GOEHR K E with visual perception. However, Repp and Knoblich Yale University (2007, 2009) recently claimed to have found effects of action on auditory perception. PITCH INCREASES FROM LEFT TO RIGHT ON PIANO Their research was based on the fact that on a piano key- keyboards. When pianists press keys on a keyboard to board, the pitch of produced tones increases from left to hear two successive octave-ambiguous tones spanning a right. Pianists are continuously exposed to this relationship, tritone (half-octave interval), they tend to report hear- whereas other musicians and some nonmusicians merely ing the tritone go in the direction consistent with their know it but do not have sensorimotor experience with it. key presses (Repp & Knoblich, 2009). This finding has On each trial of their experiment, Repp and Knoblich been interpreted as an effect of action on perceptual (2009) showed participants a pair of two-digit numbers judgment. Using a modified design, the present study that corresponded to two keys on a labeled piano keyboard separated the effect of the action itself from that of the (a silent MIDI controller). The keys always spanned the visual stimuli that prompt the action. Twelve expert pia- musical interval of a tritone (half an octave), with the sec- nists reported their perception of octave-ambiguous ond key being either higher (i.e., to the right of) or lower three-note melodies ending with tritones in two condi- than (to the left of) the first key. When participants pressed tions: In the active condition, they saw a notated melody the keys in succession according to the numerical action and played it on a keyboard to hear it, while in the pas- prompts, they heard two octave-ambiguous tones (Shep- sive condition they viewed the notation while the mel- ard, 1964) spanning a tritone (Deutsch, 1986, 1987) and ody was played to them. Participants tended to report had to report whether the interval was rising or falling. hearing the tritone as it appeared in the notation, but They perceived the tritone as matching the direction of action had no additional effect. We discuss whether the their action more often than not. This “action direction “action direction effect” described by Repp and Knoblich effect” (ADE) was much stronger for pianists than for may have been caused by the visual action prompts, not non-pianists, and pianists also showed it even when they by the action itself. sat still and observed someone else pressing the keys. One interpretation of the ADE is that performed or Received April 16, 2010, accepted August 9, 2010. observed keyboard actions automatically evoke strong Key words: tritone, tritone paradox, action, auditory associations in pianists, and that these images perception, ambiguous melodies interact with the perception of ambiguous auditory stim- uli. Indeed, there is evidence from behavioral and neuro- science studies that auditory imagery occurs when pianists press silent piano keys (Bangert, Jürgens, Häusler, RAPIDLY INCREASING VOLUME OF RESEARCH & Altenmüller, 2006) and that, conversely, perception of documents tight relationships between percep- piano tones can lead to activation of the motor system in A tion and action. While the dependence of action pianists (Drost, Rieger, Brass, Gunter, & Prinz, 2005a, on perception has long been recognized, many recent 2005b; Drost, Rieger, & Prinz, 2007; Haueisen & Knösche, studies demonstrate previously unsuspected effects of 2001; Lahav, Saltzman, & Schlaug, 2007). Other interpre- action on perception (e.g., Hamilton, Wolpert, & Frith, tations of the ADE are possible, however, as Repp and 2004; Miall et al., 2006; Schubö, Aschersleben, & Prinz, Knoblich (2009) acknowledge. The effect of action may 2001; Wohlschläger, 2000; Wühr & Müsseler, 2001; have been post-perceptual, affecting just the response Zwickel, Grosjean, & Prinz, 2007, 2010; for reviews, see decision about an ambiguous auditory stimulus, rather Music Perception VOLUME 28, ISSUE 3, PP . 315–320, ISSN 0730-7829, ELECTRONIC ISSN 1533-8312 © 2011 BY THE REGENTS OF THE UNIVERSITY OF CALIFORNIA. ALL RIGHTS RESERVED . PLEASE DIRECT ALL REQUESTS FOR PERMISSION TO PHOTOCOPY OR REPRODUCE ARTICLE CONTENT THROUGH THE UNIVERSITY OF CALIFORNIA PRESS ’S RIGHTS AND PERMISSIONS WEBSITE , HTTP ://WWW .UCPRESSJOURNALS .COM /REPRINTINFO .ASP . DOI:10.1525/MP .2011.28.3.315 MP2803_07.indd 315 1/6/11 4:33:16 PM 316 Bruno H. Repp & Robert M. Goehrke than pushing the percept in one or another direction. It at six semitones, whereas it would be nine semitones oth- is also possible that the ADE was not due to the action erwise. Replication of this context effect was also of inter- itself but to the visual stimuli that prompted the action. est, as the earlier data were rather limited. Although Repp and Knoblich varied the direction of the Furthermore, we used two sets of octave-ambiguous number labels on the keyboard and found no effect of tones with different spectral envelopes, which, according ascending versus descending numbers, the numbers that to some previous findings (e.g., Deutsch, 1987) should served as action prompts had to be translated into an yield similar results, but according to others might show action plan by the participants. The realization that a left- different response patterns (Repp, 1994, 1997) or differ- right or right-left movement was to be carried out may ences in degree of ambiguity (Repp & Thompson, 2010). have been sufficient to bias responses to the auditory Finally, we also varied the playing hand (left or right) in stimuli, with the action itself being redundant. the active condition, though we did not expect it to make The purpose of the present experiment was to address a difference. this last possibility by dissociating the action from the visual prompt that gave rise to it. This aim could be real- Method ized more effectively by using music notation instead of numbers, because notation retains its action relevance ParticiPants in the absence of a keyboard. (There is no reason to Twelve pianists were paid to participate. They included expect a pair of numbers to affect auditory perception three graduate students from the Yale School of Music and unless it is associated with an action plan.) In the experi- nine undergraduate students from Yale University. They ment, pianists either played a notated melody on a key- all played advanced repertoire, had 10-23 years of training, board and reported how the resulting sequence of and currently took lessons with Yale faculty pianists. octave-ambiguous tones sounded to them, or they just Materials viewed the notation while listening passively to the tones Octave-ambiguous tones were created using a program and then reported their impression. Whether the nota- written in MAX/MSP (version 4.0.9). Each tone con- tion would influence their judgments was an interesting sisted of six octave-spaced partials whose relative ampli- question in itself. The primary question, however, was tudes were governed by a fixed convex spectral envelope whether carrying out the action would have an effect on function centered on either 262 Hz (C4) or 370 Hz (F#4) perceptual judgment above and beyond any effect that (see Deutsch, Kuyper, & Fisher, 1987; Repp & Thompson, the notation (the action prompt) might have. If it did, 2010: Figure 1). For each envelope there were 12 tones there should be a larger effect on tritone perception in representing the 12 musical pitch classes (A, A#,…, G#). the active condition (prompt + action) than in the pas- From each set of 12 tones, 12 pairs were formed whose sive condition (prompt alone). members were separated by the interval of a tritone Our experiment also aimed to make the experimental (A-D#, A#-E, …, G#-D). Then each of those pairs was paradigm less transparent. In the Repp and Knoblich preceded with a third tone that was three semitones away (2009) study, it must have been rather obvious to the from the initial tone, either higher or lower (e.g., C-A-D# participants what the research was about, and they may and F#-A-D#). This resulted in 24 three-tone melodies have either given in to or resisted a bias induced by action for each envelope set. and/or action prompts. Indeed, there were large indi- Two notations were created for each of these melodies, vidual differences in the size of the ADE, which are dif- one in which the tritone was ascending and another in ficult to explain on the basis of sensorimotor experience which it was descending. As an example, the alternative alone, as all pianists were highly trained. In the present notations for the two melodies ending with the B-F tri- study we preceded each tritone pair with a third tone, tone are shown in Figure 1. Enharmonic equivalents (flats thus forming a three-tone melody, which was intended and sharps) were used such that the first and second notes to divert participants’ attention from the tritone intervals were always a minor third apart (e.g., Ab-Cb instead of as such. It is known from previous research that a preced- Ab-B, which would be considered an augmented second ing context tone influences tritone perception according in music theory; note that B = Cb on the piano). to a principle of pitch proximity that minimizes the range of the pitches perceived in successive octave-ambiguous tones (Repp, 1997; Shepard, 1983). Thus, for example, if Design anD ProceDure the tritone C-F# is preceded by D#, it tends to be heard The experiment was divided into 8 blocks, each containing as rising, whereas when it is preceded by A, it tends to be 48 randomly ordered trials resulting from the combination heard as falling.