ASSESSMENT OF TRANSIENT NEGATIVE AFFECT IN SYNESTHESIA A DISSERTATION IN Psychology Presented to the Faculty of the University of Missouri-Kansas City in partial fulfillment of the requirements of the degree DOCTOR OF PHILOSOPHY by KATHERINE DAWN GIMMESTAD B.S., University of Michigan, 1998 M.A., University of Missouri-Kansas City, 2010 Kansas City, Missouri 2011 ASSESSMENT OF TRANSIENT NEGATIVE AFFECT IN SYNESTHESIA Katherine Dawn Gimmestad, Candidate for the Doctorate of Philosophy University of Missouri, Kansas City, 2011 ABSTRACT The purpose of this dissertation was to investigate how synesthesia may influence affect and sensorimotor gating in synesthetes. Synesthesia is the phenomenon in which a sensory experience triggers a conscious perception that is in addition to perceptions most people would experience in response to the stimulus. The type of synesthetic experience involving colors for letters and/or numbers is indicative of grapheme to color synesthesia; the most frequently reported type of synesthesia. For example, a synesthete may report seeing the color green in response to hearing or seeing a particular number or letter. Anecdotal reports by synesthetes describe negative affect when viewing a number or letter in a color that does not match (i.e., is incongruent) the synesthete’s automatic perceptions. In addition, many reports by synesthetes indicate a greater propensity for experiencing ―sensory overload‖ than non-synesthetes. It was predicted that briefly viewing an incongruent grapheme would produce a transient negative affective state, temporarily increasing the magnitude of startle reflex as measured by eyeblinks among grapheme color synesthetes. Results did not support an interaction effect involving Presence of Synesthesia and Picture Condition, F(2 , 23) = 1.35, iii p > .05. Although magnitude of startle was greater for grapheme → synesthetes than when viewing an incongruent grapheme compared to viewing a congruent grapheme or in the baseline (no picture) condition, these results were not statistically significant. It was also predicted that, when examining sensorimotor gating in synesthetes and non-synesthetes with prepulse inhibition (PPI) as the index, synesthetes would show less PPI, indicating increased sensory overload susceptibility. This hypothesis was not supported. Although synesthetes did not display reduced PPI, significantly more synesthetes than non- synesthetes reported experiencing sensory overload, and significantly higher levels of sensory sensitivity and sensation avoiding. iv The undersigned, appointed by the Dean of the College of Arts and Sciences, have examined a dissertation titled ―Assessment of Transient Negative Affect in Synesthesia,‖ presented by Katherine D. Gimmestad, candidate for the Doctorate of Philosophy degree, and hereby certify that in their opinion it is worthy of acceptance. Supervisory Committee Christopher T. Lovelace, Ph.D., Committee Chair Department of Psychology Diane Filion, Ph.D. Department of Psychology Delwyn Catley, Ph.D. Department of Psychology Melisa Rempfer, Ph.D. Department of Psychology Heather Noble, Ph.D. Counseling, Testing and Health Center v CONTENTS ABSTRACT ..................................................................................................................... iii LIST OF ILLUSTRATIONS ............................................................................................. ix LIST OF TABLES ............................................................................................................. x ACKNOWLEDGEMENTS ............................................................................................... xi Chapter 1. INTRODUCTION ...................................................................................................... 1 2. -REVIEW OF LITERATURE ..................................................................................... 9 Characteristics and Properties of Synesthesia .............................................. 9 Genuineness of Synesthesia ........................................................... 10 Consistency ........................................................................ 10 Automaticity ...................................................................... 11 Idiosyncrasy ....................................................................... 14 Direction and Etiology ....................................................... 15 Forms of Synesthesia ................................................................................ 15 Prevalence of Synesthesia ......................................................................... 17 Potential Benefits of Synesthesia ............................................................... 17 Potential Difficulties of Synesthesia .......................................................... 19 Startle Eyeblink Modification (SEM) as a Measure of Affect ......... 20 SEM as a Measure of Affect in Synesthetes ................................... 21 Sensory Overload .......................................................................... 21 Sensorimotor Gating ...................................................................... 23 vi Prepulse Inhibition (PPI) as an Index of Sensorimotor Gating ................................................................................ 24 Variance among Populations in PPI/Sensorimotor Gating Ability ............................................................................... 24 Prepulse Inhibition as a Measure of Sensorimotor Gating in Synesthetes .................................................................... 25 Summary of Literature and Proposed Study .............................................. 26 3. _METHODOLOGY ............................................................................................... 28 Participants ............................................................................................... 28 Self-Report Measures ................................................................................ 29 Presence or Absence of Synesthesia ............................................... 29 Sensory Sensitivity ........................................................................ 31 Eysenck Personality Questionnaire-Revised .................................. 33 Startle Measures ........................................................................................ 33 Stimuli ...................................................................................................... 34 Procedure .................................................................................................. 35 Data Analysis ............................................................................................ 37 4. RESULTS ............................................................................................................. 38 Main Analyses .......................................................................................... 38 Hypothesis 1: Incongruent Graphemes and Transient Negative Affect ............................................................................. 38 Hypothesis 2: Sensory Overload and Prepulse Inhibition .............. 39 Exploratory Analyses ................................................................................ 43 5. DISCUSSION ....................................................................................................... 50 vii Appendix A. SCNL DEMOGRAPHICS FORM ........................................................................ 59 B. NIMH-NAROPA SYNESTHESIA SCREEN INTERVIEW (RESEARCH VERSION) ........................................................................................................... 60 C. SCNL SENSORY OVERLOAD QUESTIONNAIRE ............................................ 70 REFERENCE LIST ......................................................................................................... 72 VITA ............................................................................................................................... 81 viii ILLUSTRATIONS Figure Page 1. Mean Startle Response (+ SE) for non-synesthetes and synesthetes in the No Picture, Incongruent, and Congruent conditions........................................39 ix TABLES Table Page 1. Intercorrelations between Subscales of SCNL Sensory Overload Questionnaire and Adult Sensory Profile ........................................................... 42 2. Mean SCNL Sensory Overload Questionnaire Subscale Scores by Synesthetes and Non-synesthetes .................................................................. 43 3. SCNL Sensory Overload Questionnaire Scores Participants with External Synesthesia and Internal Synesthesia ................................................... 44 4. Mean Scores on Sensory Sensitivity and Sensation Avoiding Subscales by Participants with External Synesthesia, Internal Synesthesia, and Participants without Synesthesia ........................................................................ 45 5. EPQ-R Total Scores for Synesthetes and Non-synesthetes ................................. 46 6. Intercorrelations Between Subscales for Adult Sensory Profile, SCNL Sensory Sensitivity Questionnaire and EPQ-R ........................................ 47 x ACKNOWLEDGEMENTS I would first like to express my gratitude, appreciation, and thanks to the members of my dissertation committee: Drs. Christopher T. Lovelace, Diane Filion, Melisa Rempfer, Delwyn Catley, and Heather Noble. Apart from their roles as committee members, these individuals