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Development and validation of a Dog Personality Questionnaire

Dissertation
Author: Amanda Claire Jones
Abstract:
Many groups, such as rescue and service-dog programs, are interested in assessing dogs' personalities. These groups often need to assess large numbers of dogs with limited resources (e.g., in terms of facilities, trained assessors, time, money). To meet these groups' requirements, an assessment tool that measures canine personality rapidly and is demonstrably reliable and valid is needed. The Dog Personality Questionnaire (DPQ) was developed to fill this gap. This dissertation describes a series of six studies designed to develop and evaluate the DPQ. To ensure that the final instrument built on previous research and was based on a comprehensive item pool, 1,200 descriptions were culled from the dog-personality assessment literature, shelter assessments, and dog experts' input (e.g., researchers, trainers, veterinarians). Three expert judges narrowed this list to 360 items. In Study 1, these items were administered to 152 participants who gave feedback on the items' applicability and ease of use. In Study 2, exploratory factor analysis was used to determine the number of factors underlying the 360-item questionnaire, based on 3,737 participants' ratings of their dogs. Convergent criteria favored five factors, labeled as Fearfulness, Aggression towards People, Aggression towards Animals, Activity/Excitability, and Responsiveness to Training. Narrower facets within each factor were also identified. On the basis of item analyses, the questionnaire was shortened to 102 items. In Study 3, the 102-item questionnaire was administered to 2,556 new participants and further exploratory and confirmatory factor analyses were used to examine the robustness of the five-factor solution. Items were then evaluated in terms of factor- and facet-loadings, content validity, internal consistency, and other criteria in order to shorten the questionnaire to a more manageable, 75-item form, and an even briefer 45-item form. In Studies 4-6, the psychometric properties of the 75-item and 45-item DPQ were further evaluated. The DPQ was shown to have acceptable levels of inter-rater reliability (Study 4), test-retest reliability (Study 5), and predictive validity (Study 6). Discussion focuses on evaluating how well the DPQ meets the criteria that guided its development.

viii Table of Contents List of Tables ...................................................................................................................xv List of Figures ................................................................................................................xvii Chapter 1 Introduction.........................................................................................................1 Study 1: Pilot Testing the Initial Item Pool................................................................3 Study 2: Factor Structure Identification .....................................................................3 Study 3: Factor Structure Confirmation .....................................................................4 Study 4: Inter-Rater Reliability ..................................................................................5 Study 5: Test-Retest Reliability .................................................................................5 Study 6: Predictive Validity .......................................................................................6 Chapter 2 Literature Review................................................................................................7 Introduction.................................................................................................................7 Literature Review........................................................................................................8 Literature search procedures..............................................................................9 A General Survey of the Field..................................................................................11 Assessment methods........................................................................................11 Test Batteries.......................................................................................11 Ratings of Individual Dogs..................................................................12 Expert Ratings of Breed Prototypes.....................................................12 Observational Tests..............................................................................13 Breeds assessed................................................................................................14 Purpose of study...............................................................................................16 Age at testing...................................................................................................17 Breeding and rearing environment...................................................................18 Sexual status of subjects..................................................................................19 Summary of general survey.............................................................................19 Review and Evaluation of Empirical Findings.........................................................28 What Traits Have Been Studied in Dogs?.......................................................28

ix Step 1: Extracting behavioral descriptions..........................................29 Step 2: Development of temperament categories................................30 Step 3: Classification of behaviors by a panel of experts....................31 Potential limitations of sorting method............................................................33 Results from the sorting task............................................................................35 Are Assessments of Dog Personality Reliable?........................................................48 Summary of reliability findings.......................................................................56 Are Assessments of Dog Personality Valid?............................................................56 Obtaining and categorizing validity coefficients.............................................56 Convergent validity..............................................................................58 Discriminant validity...........................................................................71 Summary of validity findings..........................................................................72 Summary and Conclusions.......................................................................................73 Chapter 3 Criteria for Selecting an Assessment Method...................................................80 Introduction ..............................................................................................................80 Criteria......................................................................................................................80 Reliability.........................................................................................................81 Validity............................................................................................................81 Sensitivity........................................................................................................82 Minimal order effects.......................................................................................83 Availability of psychometric properties to the public......................................83 Comprehensiveness and detail.........................................................................83 Wide applicability............................................................................................84 Ease of use.......................................................................................................84 Efficiency.........................................................................................................84 Manageability..................................................................................................84 Summary of Criteria for Selecting an Assessment Method .....................................85 Assessment Methods ................................................................................................85 Test Batteries...................................................................................................86 Observational Tests..........................................................................................88

x Expert ratings of Breed Prototypes..................................................................91 Ratings of Individual Dogs..............................................................................92 Evaluation and Selection of an Assessment Method ...............................................96 Insight from Human Personality Research...............................................................98 Chapter 4 Study 1: Pilot Testing the Initial Item Pool ....................................................100 Introduction ............................................................................................................100 Part 1: Generating an Item Pool .............................................................................100 Initial groups of items into categories............................................................101 Removal of redundant items..........................................................................102 Review of item pool.......................................................................................103 Part 2: Administration and Feedback-Driven Revision of the DPQ ......................104 Method...........................................................................................................104 Participants.........................................................................................104 Materials and Procedures...............................................................................106 Utilizing web-based methods.............................................................106 Administration of the DPQ................................................................107 Results ............................................................................................................109 Difficult to interpret...........................................................................109 Not applicable....................................................................................109 Free-response suggestions.................................................................109 Sample demographics........................................................................110 Item Re-examination and Revision................................................................115 Difficult to interpret...........................................................................115 Free-response suggestions.................................................................116 Intermediate Questionnaire #1................................................................................117 Summary of Findings..............................................................................................117 Chapter 5 Study 2: Factor Structure Identification..........................................................118 Introduction ............................................................................................................118 Method....................................................................................................................119 Design............................................................................................................119

xi Participants.....................................................................................................120 Materials and Procedures...............................................................................120 Results ....................................................................................................................120 Sample demographics....................................................................................121 Item refinement..............................................................................................125 Analyses .................................................................................................................126 Part 1: Exploratory Factor Analysis...............................................................126 Part 2: Split-sample EFA and CFA with 353 items.......................................139 EFA....................................................................................................140 CFA....................................................................................................143 Results................................................................................................146 Part 3: Determination of trait facets...............................................................147 Part 4: Item reduction.....................................................................................152 Content validity (facets).....................................................................153 Item factor loadings...........................................................................153 Item cross-loadings............................................................................154 Internal consistency...........................................................................154 Resultant item pool............................................................................155 Part 5: Split-sample EFA and CFA with 102 items.......................................156 EFA....................................................................................................157 CFA....................................................................................................162 Results................................................................................................163 Intermediate Questionnaire #2 ...............................................................................164 Summary of Findings..............................................................................................164 Chapter 6 Study 3: Factor Structure Confirmation..........................................................165 Introduction ............................................................................................................165 Method ...................................................................................................................165 Design............................................................................................................165 Participants.....................................................................................................165 Materials and Procedures...............................................................................166

xii Results.....................................................................................................................167 Sample demographics....................................................................................168 Part 1: Confirmatory Factor Analysis.....................................................................172 Part 2: Split-sample EFA and CFA.........................................................................176 EFA................................................................................................................176 CFA................................................................................................................182 Results............................................................................................................183 Part 3: Confirmation of the Five-Factor, 15-Facet Model......................................184 Part 4: Building the DPQ Long and Short Forms...................................................185 Factor and facet loadings...............................................................................185 Content validity..............................................................................................186 Item utility......................................................................................................186 Discriminant and convergent validity............................................................186 Internal consistency.......................................................................................188 The Dog Personality Questionnaire Final Forms....................................................189 Summary of Findings..............................................................................................191 Chapter 7 Study 4: Inter-Rater Reliability ......................................................................193 Introduction ............................................................................................................193 Methods ..................................................................................................................193 Participants.....................................................................................................193 Materials and Procedures...............................................................................194 Results.....................................................................................................................195 Sample demographics....................................................................................195 Analyses.........................................................................................................200 Inter-rater reliability...........................................................................200 Summary of Findings..............................................................................................210 Chapter 8 Study 5: Test-Retest Reliability .....................................................................212 Introduction ............................................................................................................212 Methods ..................................................................................................................212 Participants.....................................................................................................212

xiii Materials and Procedures...............................................................................213 Results.....................................................................................................................213 Sample demographics....................................................................................213 Analyses.........................................................................................................218 Test-retest reliability..........................................................................218 Summary of Findings..............................................................................................226 Chapter 9 Study 6: Predictive Validity ...........................................................................227 Introduction ............................................................................................................227 Method ...................................................................................................................228 Design ...........................................................................................................228 Test Battery with subtests..................................................................228 Test Battery scoring...........................................................................229 Participants.....................................................................................................236 Sample demographics........................................................................236 Materials and Procedures...............................................................................240 DPQ....................................................................................................240 Test Batteries.....................................................................................241 Pilot testing........................................................................................242 Analyses ............................................................................................................242 Inter-rater reliability of DPQ factor and facet ratings....................................243 Inter-rater reliability of Test Battery behavioral scoring...............................245 Predictive validity: Correlation between DPQ and Test Battery ratings.......250 Summary of Findings..............................................................................................274 Chapter 10 General Discussion .......................................................................................276 Study 1: Pilot Testing the Initial Item Pool............................................................276 Study 2: Factor Structure Identification .................................................................277 Study 3: Factor Structure Confirmation .................................................................277 Study 4: Inter-Rater Reliability ..............................................................................278 Study 5: Test-Retest Reliability .............................................................................278 Study 6: Predictive Validity ...................................................................................279

xiv Evaluation against Ten Criteria..............................................................................279 Reliability.......................................................................................................280 Validity..........................................................................................................280 Sensitivity......................................................................................................281 Minimal order effects.....................................................................................282 Availability of psychometric properties to the public....................................282 Comprehensiveness and detail.......................................................................282 Wide applicability..........................................................................................283 Ease of use.....................................................................................................283 Efficiency.......................................................................................................284 Manageability................................................................................................284 General Evaluation of the DPQ..............................................................................284 Strengths and major findings.........................................................................284 Limitations and weaknesses...........................................................................289 Future directions............................................................................................294 Appendix A. 51 broad, content-based categories for sorting items.................................299 Appendix B. Study 2: Loading of 352 personality items on five varimax- rotated factors ............................................................................................................300 Appendix C. Study 2: Item list resulting from item reduction phase..............................313 Appendix D. Study 3: CFA model item loadings on five dog personality factors..........317 Appendix E. Study 3: Convergent validity – Correlations of items that load on the same factors and facets..............................................................................................321 Appendix F. Study 3: Discriminant validity – Correlations of items that load on different factors and facets..........................................................................................326 Appendix G. Study 3: Items retained and removed in creating the final DPQ forms.....342 Appendix H. DPQ Long (75-item) form and scoring sheet.............................................347 Appendix I. DPQ Short (45-item) form and scoring sheet..............................................350 Appendix J. Study 6: Test Battery subtest descriptions form..........................................353 Appendix K. Study 6. Dog behavioral assessment scoring sheet....................................356 References ............................................................................................................364 Vita ............................................................................................................375

xv List of Tables Table 2.1. Summary of empirical research on dog temperament: Study design, breed, sex, age, and assessment purpose............................................................................21 Table 2.2. Which traits have been studied in dogs? A review of past research ................37 Table 2.3. How reliable are personality measures of dogs?: Inter-observer agreement and test-retest reliability ..................................................................................52 Table 2.4. How reliable are personality measures of dogs?: Internal consistency............55 Table 2.5. Convergent validity: How well do dog personality tests predict future behavior or scores on other assessments? ..............................................................60 Table 3.1. Dog personality assessment methods' fulfillment of 10 criteria in principle and in practice.................................................................................................94 Table 4.1. Demographic information about participants in Study 1 ...............................112 Table 4.2. Demographic information about target dogs in Study 1.................................114 Table 5.1. Demographic information about participants in Study 2 ...............................122 Table 5.2. Demographic information about target dogs in Study 2.................................124 Table 5.3. Items removed from the 360-item pool due to narrow applicability..............126 Table 5.4. Convergent and discriminant correlations for the 4- and the 5- factor solutions.................................................................................................................132 Table 5.5. Confirmatory factor analysis of second half of Study 2 data (353 items)......147 Table 5.6. Confirmatory factor analysis of second half of Study 2 data (102 items)......163 Table 6.1. Demographic information about participants in Study 3 ...............................169 Table 6.2. Demographic information about target dogs in Study 3.................................171 Table 6.3. Confirmatory factor analyses: Comparative model fits for Study 3 full sample .....................................................................................................................175 Table 6.4. Confirmatory factor analysis of second half of Study 3 data.........................183 Table 6.5. Confirmatory factor analyses of full hierarchical model (factors and facets) .....................................................................................................................184 Table 6.6. Scale reliabilities.............................................................................................189 Table 6.7. 75-item DPQ confirmatory factor analyses....................................................190 Table 6.8. 45-item DPQ confirmatory factor analyses....................................................191

xvi Table 7.1. Demographic information about participants in Study 4 ...............................197 Table 7.2. Demographic information about target dogs in Study 4.................................199 Table 7.3. Item-level inter-rater reliability......................................................................204 Table 7.4. Facet- and factor-level inter-rater reliability...................................................209 Table 8.1. Demographic information about participants in Study 5................................215 Table 8.2. Demographic information about target dogs in Study 5.................................217 Table 8.3. Item-level inter-rater and test-retest reliability...............................................219 Table 8.4. Facet- and factor-level inter-rater and test-retest reliability...........................225 Table 9.1. Predicted relationships between behavioral descriptions and DPQ factors and facets..............................................................................................................233 Table 9.2. Demographic information about participants in Study 6................................237 Table 9.3. Demographic information about target dogs in Study 6.................................239 Table 9.4. Facet- and factor-level inter-rater reliability...................................................245 Table 9.5. Test Battery inter-rater reliability...................................................................246 Table 9.6. Fearfulness convergent and discriminant validity correlations......................251 Table 9.7. Aggression towards people convergent and discriminant validity correlations ......................................................................................................................256 Table 9.8. Activity/Excitability convergent and discriminant validity correlations .....................................................................................................................260 Table 9.9. Responsiveness to Training convergent and discriminant validity correlations.......................................................................................................................264 Table 9.10. Aggression towards animals convergent and discriminant validity correlations.......................................................................................................................268 Table 9.11. Mean factor- and facet-level predictive validity correlations.......................273

xvii List of Figures Figure 5.1. Scree plot of eigenvalues for 353 items (N = 3,737).....................................130 Figure 5.2 Hierarchical structure of factor score correlations in 353-item Study 2 data set................................................................................................................135 Figure 5.3. Scree plot of eigenvalues for 353 items in half of Study 2 sample...............141 Figure 5.4. Hierarchical structure of factor score correlations in 353-item Study 2 data set ...............................................................................................................142 Figure 5.5. Scree plot of eigenvalues for 102 items in Study 2.......................................159 Figure 5.6. Hierarchical structure of factor score correlations in 102- item Study 2 data set ...............................................................................................................160 Figure 6.1. Scree plot of eigenvalues for 102 items in Study 3.......................................178 Figure 6.2. Hierarchical structure of factor score correlations in 102-item Study 3 data set................................................................................................................179

1 CHAPTER 1 Introduction It is now widely accepted that non-human animals can be characterized in terms of personality (Gosling & Vazire, 2002). One species in which personality has been examined extensively is the domestic dog (Canis familiaris). It is easy to understand why dogs and their personalities have garnered extensive research attention. Not only are they the most common pet in the United States (Humane Society of the United States, 2007), ubiquitous wherever humans live, but they are also used to realize a number of essential applied goals, such as guiding visually impaired people and searching for explosives. As a result, many groups of people are interested in assessing the dogs’ personalities efficiently, reliably, and accurately. These groups include: (a) potential pet owners wanting to find a dog suitable for their particular circumstances (e.g., family dog vs. guard dog), (b) shelters seeking to identify suitable homes for dogs, (c) service-dog programs (e.g., guide dogs, hearing dogs), and (d) working-dog programs (e.g., patrol dogs, detection dogs). Many of these groups must evaluate dogs using very limited resources. They may have little time with each dog, few trained evaluators, minimal facilities, and other limitations. However, a well-validated, reliable, effective instrument for measuring dog personality that is easy and quick to use and widely applicable has yet to be developed. The goal of the research described here is to develop such an instrument and evaluate its psychometric properties, including aspects of reliability and validity. Before a tool for assessing the broad construct of dog personality could be developed, the construct to be studied had to be explicitly defined (e.g., DeVellis, 2003). For the term “personality” to be used to characterize non-human animals, and dogs specifically, “personality” must be defined and how (or whether) it differs from “temperament” must be determined. “Personality” is often reserved for discussing adult humans, and “temperament” for discussing human infants and non-human animals. However, these uses are not consistently maintained, and the terms tend to be used interchangeably (McCrae et al., 2000). I use the term “personality” because the

2 distinction between the two terms is not maintained sufficiently, nor is a distinction between them generally useful for the current purposes. Finding a definition of personality to suit all applications of the term is challenging. The phenomena studied by personality psychologists include temperament and character traits, dispositions, goals, personal projects, abilities, attitudes, physical and bodily states, moods, and life stories (John & Gosling, 2000). Only a very broad (and thus somewhat vague) definition could satisfy many personality psychologists simultaneously. For example, personality can be defined as those characteristics of individuals that describe and account for consistent patterns of feeling, thinking, and behaving (Pervin & John, 1997), a definition broad enough to capture most phenomena studied by personality psychologists. I adopt this broad definition, and my use of the term personality includes personality in all non-human animals as well as humans. The dog personality assessment tool developed in this dissertation will assess personality in terms of traits (also called factors or dimensions). I adopt Gosling’s (1998) definition of traits as “aggregate summary trends in behavior”. An individual’s traits are also consistent and reflected in the individual’s feeling, thinking, and behaving across time and situations. In order to ground the current studies in the existing literature, in Chapter 2 I summarize the dog personality literature published prior to the onset of the current study and providing the basis for the current study. Chapter 2 includes a summary of my published review (Jones & Gosling, 2005) of the literature, supplemented with four studies published between the review’s completion and the onset of this study (April, 2004-June, 2005). In Chapter 3, I define and discuss the criteria that guided my selection of an assessment method, and which I attempt to satisfy with the design of a new tool for assessing personality in dogs. In the next six chapters, I describe Studies 1 through 6, detailing the development of a questionnaire for assessing personality in individual dogs, from initial item generation to validation of the tool. Studies 1, 2, and 3 lay the groundwork for the latter three. Each study is outlined in greater detail below.

3 S TUDY 1: PILOT TESTING THE INITIAL ITEM POOL In Chapter 4, I describe Study 1, in which my goal was the development of an initial questionnaire for assessing dog personality; this study had two parts. First, I generated a pool of potential items for use in the questionnaire. The pool of items generated was intended to be as comprehensive as possible, representing as many aspects of dog behavior and personality as possible. In order to compile a very comprehensive list of descriptors, I drew together descriptors from multiple sources, including the dog personality and temperament research literature and tools used in applied settings (e.g., shelters); these sources were supplemented with items generated by dog experts. This process resulted in an initial list of 1,284 descriptors. These 1,284 descriptors served as the starting point for the process of sorting potential items based on content, eliminating items that did not fit my criteria (e.g., were applicable to very narrow contexts or only certain types of dogs, like guide dogs), and creating a list of 360 questionnaire items. In the second part of the study, I administered the items to a small sample of participants in order to attain feedback that would then help me to identify and revise questionnaire items that were difficult for participants to understand or that described situations participants’ dogs did not encounter. In this part of Study 1, the 360 items were piloted online with a sample of 152 dog owners who volunteered to fill out the questionnaire, and the questionnaire items were modified based on their feedback. S TUDY 2: FACTOR STRUCTURE IDENTIFICATION Study 2 (described in Chapter 5) had two goals: to determine the number of factors underlying the behaviors and descriptors in the 360-item questionnaire, and to begin developing a more concise and coherent scale. I administered the questionnaire online to dog owners who volunteered to participate, then I used exploratory factor analysis (EFA; principle components analysis [PCA] with varimax rotation) of the responses from 3,737 participants to the lengthy questionnaire. Convergent criteria indicate that both the four- and five-factor solutions were robust. For reasons of interpretability, the five-factor solution was selected.

4 Once the five factors (or traits) had been confirmed, items loading on each trait were analyzed using EFA (PCA, oblique [promax] rotation) in order to determine the number of facets within each trait. Fifteen facets were identified. In addition to other criteria (e.g., item univocality), the results of the trait and facet analyses provide guidance for creating a new, briefer and more manageable 102-item form of the questionnaire to be administered in Study 3. To assess the fit of the five-factor solution to the revised list of 102 items, I divided the participant set into two randomly selected halves, then repeated the EFA procedure on one half of the data (N = 1,868). Again, the five-factor solution was found to be robust and interpretable. I then confirmed, using structural equation modeling (SEM) to perform confirmatory factor analysis (CFA), that the five-factor model adequately fit the second half of the data (N = 1,869). S TUDY 3: FACTOR STRUCTURE CONFIRMATION In Chapter 6, I describe Study 3, in which my primary goal is to determine how well the five-factor structure model found in Study 2 replicates in the new, shorter questionnaire and a new sample of participants. Replication of the factor solution in a new sample is key to establishing the solution’s generalizability; if the solution does not generalize to the new sample and questionnaire, then it may be idiosyncratic to Study 2. I administered the 102-item questionnaire online to a new online sample of volunteer participants, who each rated a single dog (N = 2,556). I then used SEM to perform confirmatory factor analyses (CFA) to test the fit of the hypothesized five-factor model (derived in Study 2) to the newly collected data. Next, I examined the replicability of the five-factor model in the data from Study 3. I used the same procedure as in Study 2. First, I divided the participant set into two randomly selected halves. Then I repeated the EFA procedure on one half of the data (N = 1,278). Again, the five-factor solution was found to be the most robust and interpretable. Finally, I verified, using SEM to perform CFA, that the five-factor model adequately fit the second half of the data (N = 1,278).

5 I also examined psychometric properties of the questionnaire. In addition to the CFA results, examination of the psychometric properties (e.g., content validity, construct validity, including discriminant and convergent validity; internal consistency) guided the creation of two final forms of the Dog Personality Questionnaire (DPQ). The questionnaire from Study 2 was shortened to a “long form” of five items per facet (or 75 items) and a “short form” with three items per facet (or 45 items). S TUDY 4: INTER-RATER RELIABILITY The goal of Study 4, described in Chapter 7, was to address another type of reliability: inter-rater reliability. If a tool has high inter-rater reliability, then the ratings different observers ascribe to a target when using the tool are highly correlated. To assess how well the ratings of dogs’ personalities made using the DPQ generalize across observers, 99 participant pairs in which both people were familiar with the same dog completed the online questionnaire rating that dog. I then examined how highly the pairs of participants’ ratings correlate on each item, facet, and factor of both the long form and the short form of the questionnaire. The DPQ was found to have inter-rater reliability rates generally comparable to those found in human personality rating studies. S TUDY 5: TEST-RETEST RELIABILITY The goal of Study 5, described in Chapter 8, was to address a third type of reliability: test-retest reliability. For a questionnaire, test-retest reliability, or reliability across time, addresses the consistency of a single observer’s reports taken at different points in time. (This differs from a behavioral test, e.g., a Test Battery or Observational Test, in which test-retest reliability refers to the consistency of the dog’s behavior at two or more different assessment times.) If a tool has high test-retest reliability, then the scores that are obtained when the test is administered at time 1 agree, or are highly correlated, with the scores obtained when the test is administered again (i.e., at time 2, time 3, and so on). To assess the DPQ’s test-retest reliability, I administered the online questionnaire twice, with approximately four to six weeks between administrations, to 100 participants. I then examined how well the pairs of ratings correlate on each item,

6 facet, and factor of both forms of the questionnaire. The DPQ was found to have test- retest reliability rates generally comparable to those found in human personality rating studies. S TUDY 6: PREDICTIVE VALIDITY The aspects of reliability assessed in Studies 3-5 are crucial prerequisites for predictive validity. Predictive validity is the extent to which scores on a given measure are related to some external, independent measure. In Chapter 9, I describe Study 6, the goal of which was to address how well participants’ ratings of their dogs on the DPQ predict the dogs’ behavior on independent measures. For purpose of this study, I devised a new Test Battery to assess behavioral traits thought to be related to items on the long form of the DPQ (the five dog personality factors and their facets). One hundred participant-dog pairs were recruited to take part in the study. Owners and kennel staff completed the long form of the DPQ on paper, and the dogs were assessed using the new Test Battery. Specific behavioral descriptions assessed on the Test Battery were predicted to be related to and unrelated to specific factors and facets measured on the DPQ; these relationships were assessed using convergent and discriminant correlations, respectively. The DPQ was found to have relatively high convergent validity, as compared with other dog personality assessments; discriminant validity results were mixed.

7 CHAPTER 2 Literature Review I NTRODUCTION Early in the twentieth century, Nobel laureate Ivan Pavlov began a research program designed to identify the basic types of canine personality (e.g., Pavlov, 1906). Despite this auspicious start, the study of temperament and personality in animals did not evolve into a major area of research except, of course, in humans. Yet pet owners and practitioners working with dogs have long recognized that canine personality is important. It influences dogs’ behavior and responses to their environments. Studies of dog personality have striven to fulfill many goals, from identifying a puppy test that will predict adult guide-dog behavior (e.g., Goddard & Beilharz, 1984a, 1984b, 1986), to examining the heritability of personality traits (e.g., Reuterwall & Ryman, 1973; Wilsson & Sundgren, 1998). These studies are unified by a common interest in dog personality, but the researchers conducting these studies come from a wide variety of backgrounds, bringing with them assorted perspectives and publishing in a broad range of journals. As a consequence of their distinct disciplinary affiliations and research goals, these efforts at understanding personality in dogs have followed largely independent paths. The result is that it is hard to keep track of the various findings—the studies are scattered across journals in anthrozoology, psychology, biology, animal behavior, and veterinary medicine, among others. Each of these discipline-bound studies is interesting and valuable in its own right, but it provides only a relatively narrow glimpse of dog personality. Taken together, the studies provide broader insight not only into dog personality, but also into the strengths and weaknesses of the methods used to assess dog personality. The goal of the current chapter is to describe and discuss the various methods used to assess dog personality, to summarize the major findings from the dog personality literature, to pinpoint major gaps in science’s understanding of dog personality, and to use those gaps to inform

8 suggestions about the research challenges that lay ahead. Specifically, this chapter starts by examining general trends in research on dog personality. What methods have been used, what breeds have been assessed, and what other trends can be identified? The next issue addressed is the specific domains, or traits, of personality that have been identified in dogs. Specifically, which traits have received the most cross-study support? Next, meta-analyses of past work on the reliability and validity of personality tests are used to evaluate the effectiveness of personality measures. Finally, the findings are drawn together to offer 18 broad conclusions about the field and identify the major questions that remain to be addressed. The research reviewed in this chapter should be of interest both to practitioners and to researchers. Relevant practitioners include those interested in the practical task of identifying dogs whose personalities are well-suited to working as guide dogs, hearing dogs, or police dogs, and for various other jobs in which dogs assist people in their daily lives. The findings will also be relevant to dog shelters and rescue centers, which often rely on personality tests as a guide for placing dogs in suitable homes, and for individual pet owners interested in finding a pet suitable for their lifestyle (e.g., Coren, 1995, 1998; Hart & Hart, 1985, 1995; Tortora, 1983). With the recent moves in the United States to pass breed-specific legislation, intended to limit and control the ownership of specific breeds, this work will also be of interest to workers in animal welfare and social policy. Finally, the review will be useful to the growing body of research scientists interested in using animal models to examine basic issues in human psychology (Gosling, 2001) and animal behavior (Dugatkin, 2004). L ITERATURE REVIEW To be certain that I included as many potentially relevant studies as possible, I searched the PsycINFO, Biosis, and Web of Science databases for articles in which either personality or temperament in dogs were examined. I included only those studies in the published empirical research literature. As such, my review did not include the methods that are frequently used and well-regarded in applied settings (e.g., Sue Sternberg’s

9 Assess-a-Pet and Emily Weiss’s the SAFER and SAFER-II tests) but for which data are not yet published. Included in this chapter are only those dog personality or temperament studies published prior to the beginning of the development of the dog personality assessment tool that is the focus of the current research. That is, all articles examined in this review were published prior to June, 2005; articles published since are excluded. Literature search procedures The literature search used two basic procedures: Generating a large pool of potentially relevant articles, and selecting a smaller subset of articles for inclusion in the final review. These two procedures were used iteratively, such that one cycle generated a pool of potential articles and selected a subset of them for review, and this subset of articles provided the starting point for a subsequent cycle. In the initial search cycle searched PsycINFO, Biosis, and Web of Science databases for all articles containing the keywords “dog” and “temperament,” or “dog” and “personality.” Searches for descriptors such as “aggressive” or “fearful” were not included because almost all behavior can be described as related to some domain; including these articles would have meant capturing a vast number of articles that did not focused personality constructs but merely included behaviors related to a personality domain. For example, the study of dogs’ preference for humans by Topál et al. (1998) examined attachment behavior, including nervousness-related behaviors, but had no interest in individual differences in temperament per se. If an article did not even mention personality or temperament in the title, list of keywords, or abstract (i.e., the fields scanned in a keyword search), it was concluded that it was highly unlikely the research would be relevant to this review. After eliminating duplicates, I examined the abstracts of the remaining reports to eliminate irrelevant articles. Articles varied in their relevance to research on dog temperament; some focused directly on temperament assessment but others clearly fell beyond the domain of this review. For example, one article examined the personalities of

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Abstract: Many groups, such as rescue and service-dog programs, are interested in assessing dogs' personalities. These groups often need to assess large numbers of dogs with limited resources (e.g., in terms of facilities, trained assessors, time, money). To meet these groups' requirements, an assessment tool that measures canine personality rapidly and is demonstrably reliable and valid is needed. The Dog Personality Questionnaire (DPQ) was developed to fill this gap. This dissertation describes a series of six studies designed to develop and evaluate the DPQ. To ensure that the final instrument built on previous research and was based on a comprehensive item pool, 1,200 descriptions were culled from the dog-personality assessment literature, shelter assessments, and dog experts' input (e.g., researchers, trainers, veterinarians). Three expert judges narrowed this list to 360 items. In Study 1, these items were administered to 152 participants who gave feedback on the items' applicability and ease of use. In Study 2, exploratory factor analysis was used to determine the number of factors underlying the 360-item questionnaire, based on 3,737 participants' ratings of their dogs. Convergent criteria favored five factors, labeled as Fearfulness, Aggression towards People, Aggression towards Animals, Activity/Excitability, and Responsiveness to Training. Narrower facets within each factor were also identified. On the basis of item analyses, the questionnaire was shortened to 102 items. In Study 3, the 102-item questionnaire was administered to 2,556 new participants and further exploratory and confirmatory factor analyses were used to examine the robustness of the five-factor solution. Items were then evaluated in terms of factor- and facet-loadings, content validity, internal consistency, and other criteria in order to shorten the questionnaire to a more manageable, 75-item form, and an even briefer 45-item form. In Studies 4-6, the psychometric properties of the 75-item and 45-item DPQ were further evaluated. The DPQ was shown to have acceptable levels of inter-rater reliability (Study 4), test-retest reliability (Study 5), and predictive validity (Study 6). Discussion focuses on evaluating how well the DPQ meets the criteria that guided its development.