Draft of a submission Research Paper Manuscript for MUSICAE SCIENTIAE Inducing involuntary musical imagery: an experimental study Lassi A. Liikkanen1, 2, 3 Running head: 1 Inducing involuntary musical imagery Helsinki Institute for Information Technology HIIT, Aalto University and University of Helsinki 2 University of Helsinki, Department of Behavioral Sciences and 3 Stanford University, Department of Communications Address correspondence to Lassi A. Liikkanen, HIIT, P.O.Box 19215, FI-00076 Aalto University, Finland Email: [email protected] Author version -0- All rights reserved ABSTRACT It is still a mystery why we sometimes experience the repetition of memories in our minds. This phenomenon seems to be particularly prominent in music. We believe that present lack of knowledge relates to the lack of methods available for the study of this topic. To improve the understanding of involuntary musical imagery (INMI), this paper proposes a novel method to induce it in experimental settings. We report three experiments that were conducted to evaluate two research questions related to INMI: Can it be experimentally induced and if so, which factors influence its emergence? Investigation particularly focused on how recent activation of musical memory might predict INMI. The questions were tested in single-trial experiments conducted over the Internet. The experiments utilized a cued-recall method to induce INMI and delayed self-reports. Among a large sample of people, the prevalence of the phenomenon was considerable. When the familiarity with the stimuli was controlled for, inducing INMI experimentally succeeded in over 50% of participants. It was found that music rehearsal in the near past was a more important predictor for INMI than very recent activation of musical memories. This suggests that recent activation is a facilitating but not a necessary condition for INMI. Overall, induction of INMI is possible, and several ways to improve the method are proposed. Author version -1- All rights reserved INTRODUCTION Musical imagery is a human skill that allows us to mentally play back music. Sometimes we lose control over this power and music becomes “stuck in our thoughts”, resulting in so-called “earworms”, or repeated involuntary musical memories. How does this happen? Surprisingly, we do not have a good psychological explanation for this phenomenon (Bailes, 2007; see also; Kvavilashvili & Mandler, 2004). This is unfortunate from a psychological point of view. Instead of charming, but nonsense concepts such as earworms, this phenomenon deserves a description in psychological terms as it seems to be an integral part of music cognition. In this paper, the phenomenon is called involuntary musical imagery (Sacks, 2007) and it is abbreviated as INMI (Liikkanen, 2008). The working definition is that involuntary musical imagery refers to all imagined musical experiences that originate without the subjects’ intention and are not pathological. Recent explorations in experimental and music psychology offer insight about deliberate musical imagery (e.g. Brodsky, Kessler, Rubinstein, Ginsborg, & Henik, 2008; Godøy & Jørgensen, 2001; Halpern, 1984, 1988; Kraemer, Macrae, Green, & Kelley, 2005; Zatorre & Halpern, 2005), but research on involuntary musical imagery is only taking its first steps (Bailes, 2006, 2007; Baruss & Wammes, 2009; Bennett, 2003; Kellaris, 2001; Liikkanen, 2008, in press). For instance, this topic is included but not treated exhaustively in some recent monographs on music psychology (Levitin, 2006; Sacks, 2007). The lack of research is peculiar given that this consciousness phenomenon is more common than, for instance, synesthesia. Synesthesia is a rare condition and involves a private, mental experience akin to involuntary musical imagery, but it has still been studied extensively (see Kadosh & Henik, 2007). Author version -2- All rights reserved Involuntary musical imagery is here distinguished from clinical phenomena such as musical obsessions (Terao & Ikemura, 2000), musical hallucinations (hallucinosis), or pseudo-hallucinations (Hermesh et al., 2004). They have some commonalities, but as involuntary musical imagery seems to be a much more prevalent phenomenon than the clinical conditions, these cases are not considered here. INMI can be connected to main stream psychology through involuntary memory research, which has lately gained momentum (see Mace, 2007). Preliminary studies of involuntary semantic memory highlight INMI as likely the most prevalent form (Kvavilashvili & Mandler, 2004; Liikkanen, 2008). In contrast to involuntary semantic memories, involuntary autobiographical memories have been studied experimentally (Mace, 2005). Mace showed that explicit attempts to recall autobiographical events from elementary school and high-school years increased the number of similar involuntary memories in a subsequent diary study. Similar methods seem promising for exploring involuntary musical imagery as well. In this paper I propose a new empirical method to explore involuntary musical imagery. Specifically, I study how prior activation of musical memory relates to later INMI experiences using an induction paradigm. Employing familiarity-controlled musical stimuli, I test the power of voluntary musical imagery to evoke involuntary experiences later on. The test of this method involves the assessment of two research questions about INMI. The introduction starts by reviewing the present state of INMI research and pointing out the need for experimental research. The research questions and hypotheses relating INMI to well-known properties of cognition are introduced right after. Through three experiments I proceed to evaluate the merit of those hypotheses in predicting the emergence of INMI. Author version -3- All rights reserved Previous INMI research Perhaps the first psychological treatment of what is here called INMI was provided by psychoanalyst Theodor Reik (1953). Through introspection he identified two forms of INMI: mundane, exposure-based INMI and INMI as an indicator of repressed memories. His monograph dealt with the latter form and he hypothesized that this “haunting” music could guide psychoanalysis. For contemporary psychology, the mundane type of INMI seems more attractive and tangible. This line of research recently started as psychologists began asking questions such as how common INMI is, what kind of personality or background characteristics make people prone to it, and how pervasive it is in daily life. The survey studies of INMI conducted this far show that characteristics such as young age, gender (being female), ongoing musical activities (Bennett, 2003; Kellaris, 2001; Liikkanen, 2008, in press), and increased levels of trait neuroticism (Kellaris, 2003) or transliminality (Baruss & Wammes, 2009) are all positively related to a high retrospectively reported frequency of INMI. Transliminality is an infrequently used measure of susceptibility to internally generated psychological phenomena developed by Thalbourne and Delin (1994). The method of introspection was lately utilized by Brown (2006) who described his personal INMI experiences in great detail. A slightly different self-reporting method to study INMI was used by Bailes (2006, 2007), who used experience sampling. In her study of eleven musicology undergraduates, INMI episodes were reported frequently and were often preceded by musical activities. Most recently Beaman and Williams (2010) reported two experiments, one using a questionnaire and another involving diaries. Their results revealed considerable Author version -4- All rights reserved individual variation in experiences and a reporting bias as the survey respondents estimated the duration of the INMI episodes longer than the diary keepers. The current study This study addresses two research questions. The first question is: Can INMI be experimentally induced? This concerns whether there are experimental procedures and manipulations that can produce consistent and statistically verifiable results. If we can induce INMI in this way, the second question is: What influences the emergence of INMI? The latter question is here examined using two hypotheses about prior activation of musical memory. An important assumption of the present study is that involuntary imagery is similar to voluntary musical imagery except that it is initiated unintentionally (cf. Bailes, 2006) and tends to recur without effort. The phenomenology of INMI, for instance saliency, vividness, and musical elements of imagery, is excluded from this study (but see, Liikkanen, in press). How to induce INMI? A new method to induce INMI experiences and gather self-reports is described here. The method combines two concepts: cued memory recall and mechanisms of anticipation. Cued recall (e.g. as in Nobel & Shiffrin, 2001) is a general technique for retrieving memories in which hints are used to assist memory access. For music, cues such as lyrics or artist photographs are effective for facilitating recall of memories (Cady, Harris, & Knappenberger, 2008). Anticipation is an important feature of music cognition and refers to predicting music expected to be heard soon based on external stimuli (Huron, 2006; Levitin, 2006). It can even be considered as a form of musical imagery, namely anticipatory imagery. This capacity has been previously used to Author version -5- All rights reserved investigate implicit musical memory access in a music perception task, which revealed increased activation of left auditory cortex during gaps inserted into familiar tunes (Kraemer et al., 2005). Recently, anticipatory imagery for familiar tunes was associated with brain activity in the rostral prefrontal cortex (Leaver, Van Lare, Zielinski, Halpern, & Rauschecker, 2009). Here, the ideas of cued recall and anticipation were combined in a task that required participants to complete the lyrics for several popular songs after presentation of a cue (try completing Obladi oblada… for instance). This is considered as a variant of the musical image scanning task (Halpern, 1988), in which completing a lyrics recall task evokes musical imagery for the melody of the song (see also Cady et al., 2008). Here it was assumed that this memory activation might lead to INMI afterwards. Because this activation is based on imagery, it is devoid of many acoustic and musical features of stimuli, for instance intensity and dynamics, that are not salient in auditory imagery (Hubbard, 2010; Reisberg, 1992), but which would be present in real music and might be relevant for INMI. This procedure also allows assessing and controlling for the familiarity with the songs because open-ended completion questions require elaborate responses. A third component of the method is delayed reporting of recent conscious experiences after a distraction. This delay is crucial because it is assumed that if the participant succeeds in the intentional recall and imagery, then music representations might be maintained active in working memory. A distractor task with a variable attentional demand between the phases of the experiment is hence needed to clear out the working memory. Variable attentional demand is important because we do not know whether attentional load affects INMI and we do not want to fully suppress involuntary Author version -6- All rights reserved imagery of music either. Thus, in the absence of any evidence, we assume that any task requiring attention, not just musical, could achieve the distraction effect by capturing the participant’s attention for a while. To report INMI experiences reliably, participants must be informed about what counts as INMI. In the adapted procedure, the cued-recall task served as an illustration of musical imagery, and the definition of involuntary experience was additionally communicated to the participants when the report was requested. INMI is a currently poorly understood and unpredictable research subject. To minimize experimental artefacts due to learning and expectations, a single-trial design (Baddeley & Scott, 1971) was used. In this case it meant targeting only naive and independent participants and taking care to disguise the experiment’s real intent. A large sample of subjects was considered necessary to achieve adequate statistical power. For these reasons the experiment was implemented in an electronic medium over the Internet to gather a large, cross-sectional sample (regarding the reliability of web-based experiments, see Gosling, Vazire, Srivastava, & John, 2004; Honing & Ladinig, 2008; Skitka & Sargis, 2006). Hypotheses for the study Without any hypotheses specific to INMI to be found in literature, the working hypotheses were derived from related research. Two hypotheses were considered: most recent activation and prolonged activation. These hypotheses make different predictions about the effect of processing music on INMI. They are based on two assumptions. First, processing music by listening to it or imagining it predisposes individuals to INMI afterwards (cf. Kvavilashvili & Mandler, 2004). Second, we assume that INMI can be described as a competition of musical representations for auditory attention. This Author version -7- All rights reserved auditory attention model is derived from the competition model of visual attention (Desimone & Duncan, 1995) which claims that only the most strongly activated memory can capture attention and lead to a conscious experience. Different music memory representations have their own activation levels that determine their potency. These levels change over time due to decay and reinforcement, and they largely determine how easy these memories are to retrieve voluntarily or involuntarily. Note that this assumption remains neutral about the detailed structure of musical memory (e.g. Peretz & Coltheart, 2003). The most recent activation hypothesis is motivated by observations that people often report that INMI has been preceded by recent music listening or imagining (Bailes, 2007; also Reik, 1953). This suggests that INMI might be akin to the recency effect, a robust phenomenon established for short- and long-term memory tasks, e.g. free recall of lists (see Baddeley & Hitch, 1993; Glenberg, Bradley, Kraus, & Renzaglia, 1983; Howard & Kahana, 1999). In short-term memory tasks it describes the high accessibility of the most recently processed information, but this effect persists for learned list representations in long-term memory (Glenberg et al., 1983). The prediction here is that if several songs are processed in a short period of time, the last song is the most likely to be later experienced as INMI. This means that a rapid, transient increase in the activation level of a memory would be a more significant predictor of future INMI than baseline activity (prestimulus activation level for the memory representation; see Desimone & Duncan, 1995), assuming decay happens quite quickly afterwards. The prolonged activation hypothesis claims that consecutive memory activations for a piece of music build a high activation level that decays relatively slowly. Thus the recent activations in the past are an important precondition for INMI. Author version -8- All rights reserved This hypothesis is derived from research on involuntary memory (Kvavilashvili & Mandler, 2004), which asserts that the activation of involuntary semantic memories might be best understood through the concept of spreading and decaying activation in memory networks over an extended period of time (see also Anderson, 1983). This hypothesis predicts that among a set of songs recently activated, the song that has built up most activation over a longer time will most likely trigger an INMI experience. If this assumption holds, we should be most prone to experience familiar, recently activated music. Testing the hypotheses involved designing two experiments. The most recent activation hypothesis was evaluated by changing the presentation order of musical cues, which were supposed to trigger voluntary musical memories. A recency effect would be revealed by inspecting the serial position curve of later reports about involuntary experiences. The prolonged activation hypothesis was tested by comparing two sets of cued music, contemporary (Experiment 1) and classic hit songs (Experiment 2). The prolonged activation hypothesis predicts that contemporary music, which has more likely been more recently processed (reinforced), should evoke INMI experiences more often, regardless of the most recent processing order. If the prolonged activation was unimportant, then there might be a considerable recency effect. To differentiate between the two, we needed to control for the familiarity of the songs which would likely correlate with the amount of baseline activation. Author version -9- All rights reserved EXPERIMENTS 1 & 2 Method This section describes the procedure, analysis and general characteristics of participants for two consecutive and very similar experiments. Experiments differ only by stimuli. Both experiments 1 and 2 were organized over the Internet. They were preceded by an online pilot study (N=1553), which tested potential items and scales and urged people to describe their most recent INMI experiences to generate a database of “catchy” songs. This input was used to develop the instrument and materials for the two actual experiments that followed immediately after the pilot. Participants I recruited 9967 Finnish Internet users as subjects for Experiments 1 & 2. The recruitment process started among students in several Finnish universities. They were contacted by email and urged to participate in the “Music in Mind 2007” study accessible at the University of Helsinki web server. After the participants had completed the experiment, they were given the opportunity to invite their personal contacts via email. This option was used several thousand times and expanded the sample beyond university boundaries, only 29% of all subjects were university staff or students. For the reference, 75% of the population in Finland were using the Internet at least weekly in 2007 (Harala, 2007). The participants were assigned to experiments and experimental groups pseudo-randomly based on the entry date. The qualified respondents (see analysis subsection) were predominantly female and right-handed. The mean age was 28 years, ranging from 8 to 75 years. The majority had some musical training, the median being 1-3 years (see Table 1 for details). A Author version -10- All rights reserved minority of subjects (8%) were suffering from hearing loss, neurological disorder, or were currently under medication affecting the central nervous system. Because these characteristics did not influence the main dependent variables, these participants were also included in the study. INSERT TABLE 1 Stimuli Anecdotal evidence implies that there are differences between musical pieces in the capacity to induce INMI. However, there is currently no scientific method to assess the INMI potential or “catchiness” of a song analytically, hence a statistical approach was adopted for the selection of stimuli. Songs repeatedly reported to evoke INMI in the pilot study were chosen as the stimuli for Experiment 1 in an attempt to guarantee catchiness. In addition, a well-known classic tango that was not repeatedly nominated in the pilot was selected as a control item (see Appendix A for details). The recency effect was investigated with a variable presentation order between experimental groups. Experiment 1 involved two groups and the order of the songs was simply reversed between them. Data were collected until at least 1000 responses per group had been acquired. Procedure To induce INMI, we used a musical-image scanning task facilitated with cuedrecall. In the task the participants were instructed to complete the next three words of Author version -11- All rights reserved lyrics for five Finnish songs, presented in a serial order. Each song was cued using four or five distinctive words either from the beginning of the song or from the chorus. The cues were presented next to a text book for inputting the answer. It was emphasized that the lyrics should be filled in as (or if) remembered and verbatim recollection was nonessential. This was done to discourage the participants from consulting external data sources. The experiments had a six-phase sequence illustrated in Figure 1 and no time quota. At the start, the participants were briefed regarding the general purpose of the study (not mentioning musical imagery), the ethics of data usage, and were asked to provide consent for participation. In the second phase the subjects provided information about their past and present musical activities. This was followed by the cued-recall task (third phase). FIGURE 1 In the fourth phase of the experiment, subjects spent approximately four minutes completing a filler (distractor) task. This was an important part of the procedure as it was meant to guarantee that the participants’ attention was taken away from the recalled music and occupied by something else. The questions probed several unrelated factors including personality and non-musical involuntary memories. The distractor was followed by an experience sampling phase. This started with an explanation of what INMI was, and the respondents were asked if they had experienced INMI (distinct from cued recall) during the filler phase of the experiment (for similar procedures, see e.g. Author version -12- All rights reserved Baddeley & Andrade, 2000; Teasdale et al., 1995). If this had occurred, they were asked to identify the song among the cued songs or to name some other tune. In the final phase, background information including retrospective INMI commonality was gathered and the subjects were debriefed. Analysis The data consisting of 9967 records for both experiments were inspected and refined by applying several rejection criteria. These included an unrealistically short or long duration of the experiment (less than 2 minutes or more than 30 minutes), repeated entries from the same individual (duplicate email or IP address), semantic signs of mischief (foul language) and the lack of intra-individual variation between items. This excluded 523 subjects, and 135 cases were additionally excluded for missing data. The next part of the analysis screened the remaining 9267 participants for familiarity with the stimuli. Only those who had correctly completed lyrics for at least four of the five songs presented were included, discarding 1794 subjects (1009 for Experiment 1 and 785 for Experiment 2). The steps leading to the final sample (N=7515) are presented in Table 2. INSERT TABLE 2 The dependent variables included a familiarity index and a hit percentage for each song, both calculated over all subjects. The familiarity index represented the percentage of correctly completed songs (scaled range 0-100%) based on assessment of each response. As verbatim recall was not requested, the responses were evaluated Author version -13- All rights reserved against the gist of the song. The author thoroughly familiarized himself with the correct lyrics. First, literally correct answers were accepted and then borderline cases were judged based depending on whether it seemed likely that the person had recalled and imagined the right song. The count of reported INMI experiences during the previous phases of the experiment was transformed into a relative hit percentage probability describing how often a particular song among all stimuli induced an INMI experience (scaled 0-1). Each participant could nominate only one song. Statistics were computed in SPSS 15 and in Microsoft Excel. Only results relevant to the two research questions are reported here. Other aspects of the data are reported separately (e.g., findings for distractor tasks, extended background profiles, retrospective INMI reports; Liikkanen, 2008 and in press) due to space limitations. Results: Experiment 1 Almost all participants (99.5%) had a history of INMI experiences on at least a monthly basis. The average familiarity with the stimuli was 65.0%. The threshold of four correctly recognized songs reduced the number of eligible subjects to 991. Among them, the INMI induction generally succeeded as over two thirds (68.2%) reported experiencing one of the cued songs during the experiment (see Fig. 2). INSERT FIGURE 2 Author version -14- All rights reserved There were considerable differences in the hit percentages between the songs (Table 3). However, there was no significant effect of reversed presentation order (χ2 = 2.90, df = 4, p > .05 for Table 4), although songs A and E both had higher hit percentages in the final serial position. Thus the induction procedure did not seem to evoke a recency effect. Based on the assumption that the new stimuli might have strong prolonged activation levels and thus interfere with the serial position effects, the stimulus set was changed for the next experiment to include older songs. INSERT TABLE 3 INSERT TABLE 4 Author version -15- All rights reserved Experiment 2 Participants The participants for the second experiment were drawn from the same subject pool as in the first experiment but at a different time. There were small, but significant differences in the background variables (see Table 1). On average, subjects in Experiment 2 were older (by four years), more often male, did not listen to music so much, were less likely to be associated with a university, and had a lower retrospectively reported INMI frequency. The significance of the differences will be assessed later on. Stimuli and procedure The procedure and analyses for Experiment 2 were identical to previous experiment, but as stimuli four out of five contemporary songs were replaced by more classic ones, including older pop songs, tangos, and the Finnish national anthem (see Appendix B). An 8-year-old pop song from Experiment 1 remained as a reference item. The classic songs were expected to be more familiar, but to have lower baseline activation levels than the contemporary ones. The stimulus sets were created by a listwise permutation of these songs, so that every song appeared once in each serial position, relative positions fixed (first set: ABCDE, second: BCDEA, etc.). This produced five distinct experimental groups, and it was assumed that there would be no interaction effects in the order. Per group, 1400 responses at minimum were acquired. Author version -16- All rights reserved Results: Experiment 2 The stimuli of the second experiment were better recognized than those in the first experiment (average familiarity 88.9%). Among the 6524 qualified participants, an INMI experience was evoked less often than in the first experiment (binomial test p < .001) and 49.7% of subjects reported a primed song (see Fig. 2). There were again substantial differences between the songs in hit percentages (see Table 5A), but now there was also a difference related to different stimulus positions (χ2 = 91.59, df = 16, p < .001; for Table 5B). INSERT TABLE 5 To visualize the difference between different serial positions, the hit percentages were plotted according to the serial positions. This revealed the curve displayed in Figure 3, in which the final song position has non-overlapping 95% confidence intervals with other positions (final position 95% CI 25.6-31.6, CI range for other positions 15.5-24.0%). INSERT FIGURE 3 Results: Comparing Experiments 1 and 2 The INMI induction worked clearly better in the first experiment. Is this evidence in favour of the prolonged activation hypothesis? Do the different background Author version -17- All rights reserved profiles explain the difference between the experiments in the success of INMI induction? To examine this possibility with logistic regression, the background variables mentioned earlier were first analyzed with a log-linear model to test for possible interaction effects in predicting INMI reports. No second order or higher interactions were found for the variables. Next, the dependent variable that expressed whether the participant had reported a cued song was subjected to a binary logistic regression analysis without interaction terms. This analysis showed that gender, retrospectively reported frequency of INMI (see Table 1), age, and the experimental stimulus set were all independently associated with cueing effectiveness (Table 6). Hence the difference between the stimulus sets in the capability of inducing INMI was not only an artefact of a difference in background variables. INSERT TABLE 6 A final notable result comes from those subjects who indicated that they had experienced INMI during the experiment, but the song was none of the cued ones (see Fig. 2). This indicates that these participants comprehended the INMI reporting question. They were also asked to report how much time had passed since this song had been listened to, sung, played, or imagined. It was found that approximately one third of these songs had been activated on the same day, another third on the same week, and the rest a longer time ago (see Table 7). The fact that in two thirds of the cases songs had not been heard the same day supports the notion that baseline activation rather than immediate activation is an important precondition for INMI. Author version -18- All rights reserved INSERT TABLE 7 Discussion: Experiments 1 and 2 The results of the two experiments show that in a large and heterogeneous sample of people, involuntary musical imagery is a recognized and even a quite common feature of consciousness. Based on the collected self-reports, the adopted induction procedure worked in most cases, but was dependent upon the stimuli. The question of how prior activation influences INMI was assessed through a test of most recent and prolonged activation hypotheses. The newer songs in the first experiment evoked INMI more often than the older ones of the second experiment. This supports the prolonged activation hypothesis, indicating that presumably higher baseline activation facilitates the emergence of INMI for the newer songs. Experiment 2 provided some support for the recent activation hypothesis by revealing the existence of a recency effect for INMI. The magnitude of the effect was subtle, in comparison to differences between the songs. However, the odds for reporting a cued song over any other song were more than 2.7 fold. This suggests that cueing remarkably increased the odds for an INMI experience later on, although music outside the stimulus song set was also reported. The high number of outside songs in Experiment 2 is puzzling. Many of these songs seemed to be idiosyncratic but some current hit songs were nominated repeatedly. However, because no control condition without cueing was included, it is unknown whether or how the cueing task influenced Author version -19- All rights reserved INMI for non-cued songs through various musical and non-musical associations (Cady et al., 2008). The present data are open to alternative explanations and hypotheses. For instance, one could argue that the different songs have inherent properties, such as ‘catchiness’ (a musical structure) which operates regardless of the baseline activation and interacts with transient enforcement. This kind of musical characteristics hypothesis cannot be ruled out. However, if the musical characteristics were a very strong factor and not individually idiosyncratic, one could predict that a single song should be dominant over the other songs (assuming comparable familiarity and baseline activations). The results of Experiment 1 do not support this prediction, but the second experiment had a dominating song (D). However, it happened that this particular song was included in both experiments with statistically constant familiarity level, but had a high hit percentage only in the second. Even though this song was aged at the time of the experiment, less time had passed since its radio power play times than for the rest of the songs. The high hit percentage is more likely explained by a comparatively high prolonged activation level due to the relative freshness of the song rather than by its musical characteristics. Finally, the experiment could be criticized for lack of experimental control. Maybe the results regarding INMI and the recency effect are an experimental artefact. What if the participants did not report their involuntary imagery in the reporting phase but just recalled or recognized the stimuli from the cued-recall phase? There are some arguments to support our interpretations. First, the instructions did their best to illustrate the definition of INMI to participants, and the single-trial structure utilized in the experiment ensured that the data entries are independent. This suggests that the results Author version -20- All rights reserved are valid within the constraints of self-reporting. Second, in the sampling phase, the participants repeatedly reported experiencing songs that were outside the stimulus set, i.e. had not been cued. This result would have been impossible if the subjects had just willingly recalled earlier songs. Third, if the subjects had randomly recognized one of the songs and falsely reported this as an INMI experience, one would expect the results to show stronger serial position trends (if it were just recall of list items) and less variation between the songs overall because they were all equally well recalled (familiarity was controlled). None of these effects was observed in the experiments. Author version -21- All rights reserved EXPERIMENT 3 In Experiments 1 and 2, the song cues were presented in a serial order, but no precautions were taken to ensure that the participants did not return later on to revise missing or faulty answers. This could have been detrimental for testing the recent activation hypothesis. Experiment 1 found no recency effect and this was believed to be linked to the contemporary, less thoroughly known stimuli. A possibility is that problems in recalling the cued songs may have changed the strategy in completing the task. For instance, the participants may have initially skipped items and afterwards returned to revise them. Therefore, in a control experiment (Experiment 3), we investigated what kinds of strategies are commonly used to complete these tasks. Method Participants Thirty-four undergraduate students engaged in an introductory lesson in cognitive science were asked to volunteer in a musical memory study. None of them had participated in the previous experiments. Material and Procedure This investigation was carried out using printed materials, identical to the electronic ones used in earlier experiments including instructions. The experiment was arranged in a lecture hall and the participants were asked to proceed at their own pace and focus on their own task. The linear completion of the task was implied, but the participants were free to complete it in any order. They completed two cued-recall lyrics tasks involving the songs from Experiments 1 and 2. Immediately after completing each task, they were asked several questions regarding how they completed the task. These Author version -22- All rights reserved probed for tip-of-tongue experiences, adequacy of time, confidence of correct recall, use of imagery, and perceived proactive interference. Subjects were also asked to rank the lyrics according to the order of completion. The rank order data were used to infer a completion strategy. The strategies were classified as linear or non-linear. For instance, given songs {A,B,C} the rank order {A, B,C} would be a linear strategy, but {B, A, C} and other permutations would count as non-linear strategies. Results Responses showed that nearly all subjects were consciously aware of the involvement of musical imagery in completing the task (91.9% in agreement), as expected (Cady et al., 2008; Halpern, 1988). The material in Experiment 2 was wellknown and applying the original qualification criterion (4 of 5 songs correct), 91.9% of participants qualified. Nearly all of them (86.5%) followed a linear, item-by-item completion strategy. The songs in Experiment 1 were less well-known. Only a third of participants qualified, and their usage of a linear strategy dropped to 69.4%. This within-subjects effect indicated that the completion strategy was influenced by the familiarity with the songs. This finding called for an investigation regarding whether the non-linear patterns implied the systematic use of an alternative completion strategy. The analysis of non-linear patterns showed that the subjects were still astoundingly orderly in their work. The majority of non-linear patterns (10 of 11) contained a type of intrusion in which one of the previously skipped songs appeared later on in a “wrong” position. For example, the song B in a pattern {A,C,D,E,B}. Among the stimuli of Experiment 2, this intrusion was apparently random, but in Experiment 1 it was most often the generally best known song C, indicative of a tip-oftongue recall effect. A reversed linear strategy was never used. Author version -23- All rights reserved Discussion Experiment 3 investigated how a cued musical memory task such as used in Experiments 1 and 2, is commonly performed. The results demonstrate that the participants relied on musical imagery and predominantly on a linear, item-by-item completion strategy. However, if the material was more unfamiliar, participants sometimes chose a non-linear strategy. The significance of this finding for the recency hypothesis is that the differences in completion strategies create an additional source of variance for data. This variance might partially explain the lack of a recency effect in Experiment 1, which utilized stimuli that the subjects were less acquainted with, and consequently the use of non-linear completion strategies was more probable. However, the effect was likely attenuated because the familiarity was controlled for and subjects most unfamiliar with the stimuli were left out. For Experiment 2, the non-linearity was unlikely to be a problem, because for these stimuli the use of linear response strategies dominated, and the few non-linear cases were randomly distributed among the songs. Author version -24- All rights reserved GENERAL DISCUSSION Involuntary musical imagery has remained unexplored for a surprisingly long time. Inspired by the recent advances in studies of involuntary memory, the goal of the present study was to introduce an experimental research method for assessing INMI. Results from the three experiments show that the participants could be induced to experience INMI by first activating their musical memory. We believe that the induction method will be a useful starting point for future experiments, with some room for improvements. For instance, controlling the presentation time, sequence, stimulus familiarity, and selecting cues strategically could enhance the quality of data by reducing variation. Generally, the study of the topic would be greatly served if one could get around the necessity of self-reporting, which afflicts all present research efforts. This is a prospect for future studies using physiological measures of the brain and body. Having collected empirical data about INMI, I tried to relate these data to psychological theories. After introducing a competition model of auditory attention (cf. Desimone & Duncan, 1995), our question was: If there are several distinct musical memories activated in a short time window, what determines which musical representation might gain a competitive edge and be later experienced as INMI? We presented evidence in favour of two memory-related hypotheses. A recency effect supporting the most recent activation hypothesis was discovered, but it was too small to predict the emergence of INMI in the majority of cases. Instead, the evidence is more compatible with the prolonged activation hypothesis and the notion of long-term accumulating, or spreading, activation in memory. In other words, INMI is grounded in the activation levels of permanent memory which are transformed over a longer period Author version -25- All rights reserved of time by repeated exposure to music. This indicates that INMI might be a memory feature distinct from the momentary effect of semantic priming (Lucas, 2000), or recency (Baddeley & Hitch, 1993; Glenberg et al., 1983), and not predictable from mere familiarity with music. This means that familiarity with the processed music is not adequate but (can be) a necessary condition for INMI. Additionally it was found that processing the same song as a part of two different stimulus sets changed the resulting hit percentage remarkably, which could be generally interpreted as compatible with the competence model of auditory attention. However, as this experiment relied on well-memorized musical material, it must be noted that musical properties may influence which music can be memorized and how easily. This would have indirect impact on INMI as well and cannot be ruled out here. Having argued about the role of permanent memory in INMI, what can we say more generally about its relation to mind and brain? There are some hints that INMI is a by-product of human learning mechanisms (Liikkanen, in press), and the biological foundations of INMI could be linked to consolidation and long-term potentiation (Malenka & Nicoll, 1999). The tentative evidence for this claim is that just like the characteristics of general learning capacity and memory performance (Addis, Wong, & Schacter, 2008; Burke & MacKay, 1997), the disposition to INMI has been shown to decrease with aging (Bennett, 2003; Liikkanen, 2008; see also Schlagman, Kvavilashvili, & Schulz, 2007). However, addressing this question thoroughly will require longitudinal studies. Even if this mnemonic proposition turns out to be true, it is uncertain whether INMI is functional or epiphenomenal with regard to musical memory (cf. Pylyshyn, 2002), i.e. is the experience of INMI necessary for normal memory function or not. Author version -26- All rights reserved One could criticize the aims of this experiment and ask whether it is not against the very nature of INMI that it should be controlled, i.e. experimentally induced? Is INMI induction not a conceptual paradox? The way I see it, it is appropriate to try to induce INMI because it is defined as an involuntary phenomenon. There is a difference between an involuntary memory recall and automatic (internal regulation), controlled (voluntary regulation), or spontaneous (no regulation) memory recall. This could be compared to administration of a skin paste that contains a possibly irritating agent and is expected to cause rash later on. The appearance of rash is neither automatic, nor controlled, nor spontaneous, but if rash can be observed and reported reliably then we have a method for inducing it, even if we do not understand the causal mechanisms in detail. Following the same logic, INMI induction is a valid approach if we can rely on the measurement of outcome. In conclusion, the present study confirmed that experimental research can investigate INMI and test related hypotheses. The present findings are still preliminary and follow-up studies with musical stimuli and controlled long-term exposure are needed. The validity of induction methods should be established and the phenomenology of “induced” vs. “spontaneous” INMI experiences should be studied. Future theories should elaborate the relation of INMI to the conceptions of attention, memory, and consciousness (Brown, 2006). The present results suggest that high baseline activation combined with transient enforcement is an important precondition for INMI and neither of the components alone is enough. In other words, it is not simply the latest song that we have on our minds, the songs of Yesterday count as well. AcknowledgementsI thank all people who helped me in developing this paper, including Markus Mattsson, Sinikka Hiltunen, Irma-Leena Notkola, Antti Oulasvirta, Author version -27- All rights reserved Sirke Nieminen, Jari Lipsanen, Heikki Summala, and Tuukka Sandström. Otto Lappi helped to organize Experiment 3. The contribution of volunteer participants was immeasurable and the final form of the paper owes much to the comments of anonymous reviewers and Bruno Repp. The publication process was supported by Academy of Finland research project Musiquitous. The results discussed in this paper were initially presented at the 7th Triennial Conference of European Society for the Cognitive Sciences of Music (ESCOM 2009). Author version -28- All rights reserved TABLE CAPTIONS TABLE 1 Background characteristics of the qualified participants in Experiment 1 and 2. TABLE 2 Analysis of discarded data, showing the steps leading to the final sample size TABLE 3 The songs of Experiments 1 and 2 and their average familiarity indexes calculated over all subjects and overall hit percentages among qualified subjects reporting a cued song. Note. The song D1 was the same in both experiments. TABLE 4 Hit percetanges for the different stimuli songs utilized in Experiment 1 for two experimental groups, which had a reversed presentation order. Data are arranged by stimulus position, cue identities in parentheses. TABLE 5 Hit percentages for the stimuli utilized in Experiment 2. The table is organized by different serial positions, cue identities in parentheses. Author version -29- All rights reserved TABLE 6 Results of a binary logistic regression analysis. Factors that explain the difference in reporting a cued song as INMI as a function of gender, previous INMI experiences, age, and different set of stimuli (Experiment 1 or 2). Statistics include square and standard error for the beta coefficient (B^2 and S.E. respectively). TABLE 7 The frequencies of reports to how long ago did the participant say they had heard, imagined, or performed music that they reported as the most recent INMI experienced in cases where this song was none of the cued ones. Author version -30- All rights reserved TABLE 1 Exp. 1 (N=991) Exp. 2 (N=6542) Overall (N=7515) Exp. 1 Singing, playing or composing 77.5 % 70.5 % 71.4 % Not at all 36.8 % 22.5 % 29.5 % 28.6 % Monthly or seldom 12.9 % Weekly 26.1 % 23.7 28.2 27.7 Daily, < 2h 17.5 % Mean age Daily, > 2h 6.7 % Handedness Music listening activity Right 89.4 % 89.6 % 89.6 % Daily, > 2h 68.9 % Left 7.5 % 6.9 % 7.0 % Daily, < 2h 22.8 % Ambidext. 3.1 % 3.5 % 3.4 % Weekly 8.2 % Monthly or never 0.2 % Retrospective evaluation of INMI frequency in daily life Music studies in the past Several times a day 33.7 % 26.3 % 27.3 % None 35.7 % Every day 37.3 % 33.7 % 34.2 % < 1 years 16.8 % Weekly 24.7 % 32.6 % 31.6 % 1-3 y. 22.9 % Monthly 3.8 % 5.5 % 5.2 % 4-10 y. 8.8 % More seldom or 0.5 % 1.9 % 1.7 % 10-15 y. 2.6 % never >15 y. 13.3 % Sex Women Men Author version -31- Exp. 2 Overall 35.4 % 13.8 % 27.6 % 16.9 % 6.3 % 35.6 % 13.7 % 27.4 % 17.0 % 6.4 % 53.7 % 29.8 % 14.6 % 1.9 % 55.7 % 28.9 % 13.8 % 1.6 % 29.6 % 18.4 % 25.2 % 10.7 % 4.9 % 11.1 % 30.4 % 18.2 % 24.9 % 10.5 % 4.6 % 11.4 % All rights reserved TABLE 2 All entries -Rejected:duration, duplicates, mischief Eligible candidates -Rejected: less than 4 songs recognized -Rejected: missing response to INMI song identity Valid participants familiar with stimuli Author version -32- Percent of All Entries All 9967 523 9444 94.8 % 1794 135 7515 75.4 % Exp. 1 2172 161 2011 1009 11 991 Exp. 2 7795 362 7433 785 124 6524 All rights reserved TABLE 3 Song A1 B1 C1 D1 E1 Author version Experiment 1 Contemporary Familiarity Hit rate (N=2172) (N=675) 0.573 11.3 % 0.497 21.0 % 0.871 20.4 % 0.781 8.7 % 0.526 38.5 % Song A2 B2 C2 D1 E2 -33- Experiment 2 Classics Familiarity Hit rate (N=7795) (N=3231) 0.972 2.8 % 0.942 13.6 % 0.787 27.8 % 0.768 50.5 % 0.975 5.4 % All rights reserved TABLE 4 Position 1 2 3 4 5 Author version Group 1 (A1) 9.6 % (B1) 22.2 % (C1) 21.0 % (D1) 7.8 % (E1) 39.3 % Group 2 (E1) 37.7 % (D1) 9.6 % (C1) 19.9 % (B1) 19.9 % (A1) 12.9 % -34- Mean 23.2 % 15.5 % 20.0 % 13.6 % 25.4 % All rights reserved TABLE 5 Order First Second Third Fourth Last Group 1 (A2) 2.8 % (B2) 13.1 % (C2) 27.6 % (D1) 48.4 % (E2) 8.0 % Author version Group 2 (E2) 5.7 % (A2) 1.4 % (B2) 10.3 % (C2) 22.1 % (D1) 60.6 % Group 3 (D1) 46.6 % (E2) 5.7 % (A2) 2.2 % (B2) 11.0 % (C2) 34.6 % -35- Group 4 (C2) 30.2 % (D1) 44.4 % (E2) 3.9 % (A2) 3.0 % (B2) 18.5 % Average Group 5 (B2) 15.1 % 20.9 % (C2) 25.4 % 18.4 % (D1) 51.2 % 19.5 % (E2) 3.7 % 19.4 % (A2) 4.5 % 28.6 % All rights reserved TABLE 6 95% CI for B^2 Independent variable Sex Retrospective INMI frequency Stimulus set Age Author version B 0.5392 B^2 1.7146 S.E. B 0.0522 p < .001 Wald 106.55 Lower 1.5478 0.2903 -0.7533 0.0127 1.3368 0.4708 1.0127 0.0251 0.0741 0.0030 < .001 < .001 < .001 133.80 103.47 17.61 1.2727 0.4072 1.0068 -36- Upper df 1.8995 1 1.4042 0.5443 1.0187 1 1 1 All rights reserved TABLE 7 Less than twenty minutes A few of hours Today This week Longer time ago Cannot tell N Author version Exp. 1 8.1 % 10.2 % 20.4 % 34.3 % 18.7 % 8.1 % 626 -37- Exp. 2 6.2 % 6.3 % 14.9 % 30.0 % 29.9 % 12.6 % 2997 Total 6.5 % 7.0 % 15.9 % 30.7 % 28.0 % 11.9 % 3623 All rights reserved FIGURE CAPTIONS Figure 1. Flowchart of the six phase procedure used in Experiments 1 and 2. Minutes indicate estimated average completion times for each phase among qualified participants. Figure 2. Success of induction procedure in the two experiments. Vertical bars display percentages of people reporting a cued song, some other song or no song in the experience sampling phase. The error bars denote 95% confidence intervals for the hit percentages. Figure 3. Results of the INMI induction Experiment 2. The figure illustrates the average hit percentages over all songs relative to the serial positions (N=3242). Error bars denote 95% confidence intervals for the hit percentage. f Author version -38- All rights reserved 1. Briefing & Consent ~1 min. 2. Musical background ~2 min. 3. Induction procedure (cued-recall) a) Somewhere over the… b) Obla-di, obla-da, life… c) Rudolf the Rednosed… etc. (examples not real) ~1 min. 4. Filler task ~4 min. 5. Experience sampling for INMI ~1 min. 6. General background & Debriefing ~1 min. Figure 1. Author version -39- All rights reserved Percentages of participants reporting INMI 80% Cued song 68.2% 70% 60% Other song 49.7% 50% None 40% 32.0% 30% 18.6% 20% 18.3% 13.2% 10% 0% Exp. 1 Contemporary (N=991) Exp. 2 Classics (N=6524) Figure 2. Author version -40- All rights reserved 35% Average hit rate 30% Hit percentage 25% 20% 15% 10% 5% 1 2 3 Serial position 4 5 Figure 3. Author version -41- All rights reserved Appendix Table A. Songs and presentation orders in Experiment 1. Composer Title A Linna K. Kultainen Nuoruus B Sjöroos J. Joku Raja C Vuorinen M. & Leave Me Alone Huttunen M. D Kolehmainen M. Lopeta E Virtanen T. Pokka Presentation order Group 1 A, B, C, D, E Group 2 E, D, C, B, A Genre Tango Contemporary rock Contemporary pop First release 1949 2007 2007 Contemporary pop Contemporary rock 1999 2007 Table B. Songs and presentation orders in Experiment 2. Composer A Pacius, F. B Nieminen P. C Markkula R. D Kolehmainen M. E Mononen U. Stimulus sets Set 1 Set 2 Set 3 Set 4 Set 5 Author version Title Maamme (National Anthem of Finland) Autiotalo Sä Kuulut Päivään Jokaiseen Lopeta Satumaa Genre Classic First release 1848 80’s rock Tango 1984 1972 Contemporary pop Tango 1999 1955 A, B, C, D, E E, A, B, C, D D, E, A, B, C C, D, E, A, B B, C, D, E, A -42- All rights reserved REFERENCES Addis, D.R., Wong, A.T., & Schacter, D.L. (2008). 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