This article explores why rapport seems challenging to define in the investigative interviewing literature. To demonstrate this issue is contemporary, I examined the most recent publications on rapport (August 2021 - January 2023; N = 19). Approximately 50% of the articles did not define rapport or posited multiple definitions, making a definitional preference impossible to detect. The 50% that specified a focal or single definition came with some form of suggestion that they were real definitions—the objective definitions of rapport. But all those definitions were different, highlighting the ambiguity of rapport in the literature. I discuss how a pragmatic approach via nominal definition can assist in flagging a single sense to use the word rapport, thereby eliminating ambiguity and limitations in assessing construct validity.

This article explores why rapport seems challenging to define in the investigative interviewing literature. That research domain examines social interactions in which human interviewers solicit information from human sources for security or legal purposes. The consensus is that rapport is crucial; an interviewer must induce rapport to elicit information effectively (Vrij et al., 2017). But rapport’s definition is ambiguous and inconsistent across the literature (Gabbert et al., 2021). That state of affairs invites construct validity limitations. One cannot determine a standard to evaluate operationalizations or the measurement of rapport. Consequently, the mechanisms underlying rapport’s ostensible effects remain a mystery. And any attempt to uncover it would be handicapped at once because rapport denotes different things.

Neequaye and Mac Giolla (2022) highlight the ambiguity and inconsistency in rapport definitions. The authors reviewed the relevant literature (N = 228) published until 2020, examining the scope of variance and commonalities in existing rapport definitions. The findings uncovered 22 unique definitions with considerable variance. All of them suggested that rapport concerned the quality of the interviewer-interviewee interaction but differed in their characterization of that quality. The definitions featured six primary attributes— communication, mutuality, positivity, respect, successful outcomes, and trust (Neequaye & Mac Giolla, 2022). However, those attributes did not feature systematically; they were distributed disparately across definitions. For example, some authors defined rapport by focusing on positivity (e.g., Klein et al., 2015), and others defined it in terms of interpersonal trust (e.g., David et al., 2018)

The review by Neequaye and Mac Giolla (2022) documented the variance in attributes of definitions and the corresponding limitations. The present article builds on Neequaye and Mac Giolla and delves into a conceptual analysis going beyond attribute variance of definitions. This work focuses on why the variance in definitions persists and features in the contemporary literature—even after Neequaye and Mac Giolla’s review. Furthermore, my proposal accommodates the implementation of diverse research methods to arrive at a consensus rapport definition—for example, Neequaye and Mac Giolla (2022) recommend that stakeholders define rapport using a lexical methodology.

Research domains can arrive at consensus definitions that allow objective assessment of construct validity by knowing what they are trying to explain. Recent publications indicate that confusion surrounds what needs to be known about rapport. It is useful to provide some context to unpack the suspected confusion and what I mean by knowing what one is trying to explain. Consider the following excerpts.

“Rapport is notoriously difficult to operationalize […], both because of problems in defining exactly what constitutes rapport within investigative contexts, and problems in measuring it […]. Regardless of the definition used, there is considerable agreement that rapport-building should feature prominently in the modern investigative interview (Richardson & Nash, 2021, p. 2).”

“Despite acknowledging its importance, relatively little is known about the nature and function of rapport itself (Matsumoto & Hwang, 2021, p. 1).”

Suffice it to say that the listed publications examined what they call rapport. But why would rapport be prominent in research if it is elusive, as Richardson and Nash (2021) mention? And how can rapport be critical when its nature is relatively unknown, as Matsumoto and Hwang (2021) suggest?

Rapport seems challenging to grasp because this group of language users continues to posit or search for real definitions—efforts to define rapport as an objective thing rather than what the word means. The pursuit of real definition is responsible for the confusion surrounding what constitutes rapport. Psychological concepts, like rapport, are unamenable to real definition due to their abstract nature. Thus, attempting to define rapport as an objective thing breeds statements like “rapport has proven a difficult concept to define (Alison & Alison, 2017, p. 270)” or “relatively little is known about the nature of rapport (Matsumoto & Hwang, 2021, p. 1)”. The ambiguity and concomitant construct validity limitations can be resolved by nominating a definition of the word rapport. What the investigative interviewing research domain first needs to know about rapport is what stakeholders want the word rapport to refer to—a nominal definition. We must abandon pursuing real definition; nominal definition is the tenable path to mitigating the issues plaguing the literature when it comes to defining rapport.

I will first demonstrate that the issues with defining rapport are contemporary. Then, the arguments about real versus nominal definitions in this context can follow.

Inclusion Criteria and Search Strategy

I conceived this project on August 20, 2021, and planned to include the literature published between August 16, 2021, and January 18, 2022 (see preregistration: https://osf.io/2f5ts). But I expanded the timeline to January 22, 2023, because time constraints prevented me from commencing the review on the intended start date. The expansion was necessary, given the goal of highlighting a contemporary issue.

Like Neequaye and Mac Giolla (2022), the key search term was “Rapport”, which was complemented with auxiliaries to assist in flagging publications within this review’s scope. The formal search strategy was: Rapport AND “Investigative interview*” OR Suspect* OR Eyewitness* OR “Police” OR “Interrogation” OR “Cognitive interview” OR “PEACE model” OR “Intelligence gathering” OR “NICHD”. I complemented the formal search strategy with a Google Scholar alert.

The search returned 23 publications, and I examined the full text of the search results, not just abstracts or keywords. Three articles were excluded because examining rapport was tangential to their aims, and one article was not on investigative interviewing. Nineteen publications underwent the review, and I extracted four elements for analysis using the procedure outlined below.

Elements-1 and -2: The Importance of Rapport and Challenges Defining it

Element-1 was whether a publication explicitly invoked the assertion that rapport is crucial in investigative interviewing. Under Element-2, I highlighted whether the authors mentioned that rapport was challenging to define.

Elements-3 and -4: Identifying Definitions and their Nature

I extracted definitions (Element-3) using Neequaye and Mac Giolla’s (2022) protocol. Definitions comprised the predicates of sentences or parts of a publication’s text that explicitly told readers what the authors meant by rapport.

Then I examined the nature of those definitions, focusing on the presence or absence of real definitions (Element-4). If the authors described their definition using dissociation, I noted it as a presence of a real definition—if the definition appeared to offer what the authors believed is the correct description of rapport. Dissociation entails positing what a term is—arguing for indispensable characteristics of a presumed thing—rather than what a word means—how stakeholders use a term. Dissociation is enacted by implicitly or explicitly claiming that some definition X—with attribute P(1-n)—is the true or correct instance of a term T. And other definitions Y are deficient in explicating T. A dissociative definition, essentially, argues that the criterion for correctly flagging X is P(1-n). See Schiappa (1993) for an extensive discussion on dissociation.

I ensured that dissociation was identified via a perspective-independent method that avoids recapitulating an attempt to introduce a definition. Thus, the primary verbs in sentence predicates bringing readers to discern authors’ preferred definitions did not count toward flagging dissociation. For example, “we define rapport as”; “rapport is”;”rapport refers to”; “rapport indicates—something”, and something is the definition.

Markers of dissociation comprised auxiliaries further describing the nature of a proposed definition. Such auxiliaries included: (a) adverbs and adjectives within a definitional sentence—for example, rapport is typically described as or broadly defined as something, something being the definition; and (b) discussions aimed at elaborating on a definition.

This results presentation aims at facilitating clarity. A supplemental table provides all the extractions in one snapshot and the excluded publications: https://osf.io/u7a62.

The idea that rapport is pivotal in investigative interviewing was unanimous. Authors expressed that sentiment explicitly or alluded to rapport’s importance by noting its benefits (see supplemental table). Examples include “rapport is a central component of an information-gathering approach (Brimbal et al., 2021)” and “rapport has been […] associated with a range of beneficial outcomes (Gabbert et al., 2021)”.

Despite the univocality of rapport’s significance, most authors said there was trouble defining the term (13/19 publications ~ 70%). That challenge was evident when examining the presence and absence of definitions. Approximately 52% of the publications (10/19) either did not define rapport (2/19) or posited multiple definitions (8/19), making a definitional preference impossible to detect (see Table 1).

Table 1.
Imprecise specifications of rapport definitions
SourceNature of imprecisionFlagged definitions of rapporta
Dando et al. (2022)  Multiple definitions Rapport-building, also referred to as prosocial behaviour or supportive/attentive behaviour, is believed to be important […] (p. 1). […][R]apport is often subjectively described, for example as a bond, a connection to another, and a communicative alliance, and rapport behaviours are variously operationalised, both theoretically and empirically. (p. 2) 
Dianiska et al. (2021)  Multiple definitions Rapport has been variously defined as a working relationship or connection between an interviewer and an interviewee [...] or a smooth, positive interpersonal interaction [...]. […] [Rapport] is generally believed to involve a positive or warm engagement that involves mutual respect and a productive relationship. (p. 341) 
Hagsand et al. (2022)  Two terms with one definition [Rapport and Relationship building] [a]im[s] at finding common ground, showing interest, meeting the suspect’s basic needs, showing mutual respect and empathy. (p. 2) 
Izotovas et al. (2021)  Two terms with one definition […][R]apport and relationship building is where the interviewer and subject come to a mutual understanding of one another’s needs and goals [(Kelly et al., 2013)]. (p. 746) 
Matsumoto & Hwang (2021)  Multiple conceptualizations Discusses conceptualizations of rapport without honing in on a definition. (see pp. 2 - 3, "Previous attempts to explicate rapport components") 
Nahouli et al. (2021)  Multiple definitions Rapport is often variously and abstractly described across domains, such as being a “harmonious, empathetic, or sympathetic relation or connection” […], “a smooth, positive interpersonal interaction” […], or “a relationship marked by conformity” [..]. (p. 2) 
Richardson & Nash (2021)  Multiple definitions […][R]apport has been defined as a ‘harmonious, empathetic, or sympathetic relation or connection’ between people […], other definitions point towards the promotion of equality, openness, and acceptance within interactions […], or to matching of behaviour, displays of empathy, and establishing common ground […]. Broadly, it is argued that rapport is achieved through communicating positivity, friendliness, and mutual attention […]. (p. 2) 
Wilson et al. (2022)  Multiple definitions […][R]apport has been defined in different ways, such as positivity between interactants (Bernieri & Gillis, 2001); togetherness or harmony […]; operational accord […]; an open, interested and warm relationship […]; interviewers’ positive attitudes toward interviewees and conveyance of genuine respect […]; and a positive relationship composed of trust and communication […]. (p. 2) 
Hoogesteyn et al. (2023)  No definition None 
Hwang & Matsumoto (2020)  No definition None 
SourceNature of imprecisionFlagged definitions of rapporta
Dando et al. (2022)  Multiple definitions Rapport-building, also referred to as prosocial behaviour or supportive/attentive behaviour, is believed to be important […] (p. 1). […][R]apport is often subjectively described, for example as a bond, a connection to another, and a communicative alliance, and rapport behaviours are variously operationalised, both theoretically and empirically. (p. 2) 
Dianiska et al. (2021)  Multiple definitions Rapport has been variously defined as a working relationship or connection between an interviewer and an interviewee [...] or a smooth, positive interpersonal interaction [...]. […] [Rapport] is generally believed to involve a positive or warm engagement that involves mutual respect and a productive relationship. (p. 341) 
Hagsand et al. (2022)  Two terms with one definition [Rapport and Relationship building] [a]im[s] at finding common ground, showing interest, meeting the suspect’s basic needs, showing mutual respect and empathy. (p. 2) 
Izotovas et al. (2021)  Two terms with one definition […][R]apport and relationship building is where the interviewer and subject come to a mutual understanding of one another’s needs and goals [(Kelly et al., 2013)]. (p. 746) 
Matsumoto & Hwang (2021)  Multiple conceptualizations Discusses conceptualizations of rapport without honing in on a definition. (see pp. 2 - 3, "Previous attempts to explicate rapport components") 
Nahouli et al. (2021)  Multiple definitions Rapport is often variously and abstractly described across domains, such as being a “harmonious, empathetic, or sympathetic relation or connection” […], “a smooth, positive interpersonal interaction” […], or “a relationship marked by conformity” [..]. (p. 2) 
Richardson & Nash (2021)  Multiple definitions […][R]apport has been defined as a ‘harmonious, empathetic, or sympathetic relation or connection’ between people […], other definitions point towards the promotion of equality, openness, and acceptance within interactions […], or to matching of behaviour, displays of empathy, and establishing common ground […]. Broadly, it is argued that rapport is achieved through communicating positivity, friendliness, and mutual attention […]. (p. 2) 
Wilson et al. (2022)  Multiple definitions […][R]apport has been defined in different ways, such as positivity between interactants (Bernieri & Gillis, 2001); togetherness or harmony […]; operational accord […]; an open, interested and warm relationship […]; interviewers’ positive attitudes toward interviewees and conveyance of genuine respect […]; and a positive relationship composed of trust and communication […]. (p. 2) 
Hoogesteyn et al. (2023)  No definition None 
Hwang & Matsumoto (2020)  No definition None 

Note. aBold text flags markers of imprecision.

The remaining publications, 48% (9/19), provided a single focal definition, allowing an analysis of their nature. All but one of those publications that specified definitions (8/9) came with some form of dissociation. Thus, most of those publications attempted to posit a real definition of rapport in investigative interviewing. The dominant dissociation style (Dissociation-1 in Figure 1) was implemented five times, whereby authors suggested that their definitional preference characterized the essential component(s) of rapport. Crough et al. (2022) noted that their definition precisely explicated the nature of rapport in investigative interviewing. Others mentioned that their definition is synonymous with rapport (Marin & Gabbert, 2022); is considered to be rapport (Foster et al., 2022); and the typical (Nahouli et al., 2022) or a complete (Nahouli et al., 2022) description of rapport.

Figure 1.
Flow chart outlining how recent publications describe rapport in investigative interviewing
Figure 1.
Flow chart outlining how recent publications describe rapport in investigative interviewing
Close modal

The other dissociation styles (Dissociation-2 and -3 in Figure 1) appeared twice, respectively. All the invocations of Dissociation-2 comprised authors pitching a broad definition, suggesting it encapsulates any conceivable status quo of rapport’s meaning (Brimbal et al., 2021; Hoekstra & Verhoeven, 2021).

The other form of dissociation authors used was proposing new definitions to improve existing ones (Dissociation-3). Gabbert et al. (2021) proposed “professional rapport” to distinguish rapport in investigative interviewing from rapport in other social contexts. The authors indicated that intentionality (when facilitating a positive interaction) was the distinctive component. Crough et al. (2022) posited “interrogative rapport”, arguing that it improves on professional rapport (viz., Gabbert et al., 2021). Crough et al. (2022) noted that interrogative rapport accounts for the adversarial function of rapport in suspect interviewing.

In all, the findings indicate that the ambiguity surrounding the definition of rapport persists (see also Neequaye & Mac Giolla, 2022). Half of the most recent publications did not specify a focal definition. And publications that specified a definition appeared to posit a real definition (see Figure 1). I examined the consistency between those definitions by inspecting the attributes that characterized them. Neequaye and Mac Giolla (2022) flagged the attributes authors typically use when defining rapport: positivity, mutuality, communication, successful outcomes, trust, and respect. Those attributes guided my inspection strategy.1

All but one of the nine definitions indicated that positivity characterizes rapport—positivity being an interaction that participants might find pleasant. But the definitions came with different attributes than positivity (see Table 2). For example, Brimbal et al.’s (2021) definition included the attributes positivity, respect, and trust—while Hoekstra and Verhoeven (2021) defined rapport with positivity and mutuality (of communication).

Table 2.
Specified rapport definitions with their nature and attributes
SourceDefinition of rapportaAttributes of definitionaDissociation strategy of definitionb
Brimbal et al. (2021)  Here we adopt a broad definition that characterizes the relationship between the interviewer and subject with a generally positive exchange1; attentiveness toward one another’s concerns1; and the importance of developing respect6 and trust5. (p. 56) Positivity1, Respect6, Trust5 D2: […] a broad definition that characterizes the relationship between the interviewer and subject. (p. 56) 
Crough et al. (2022)  [Interrogative Rapport:] [A] temporary working relationship1 created strategically by the interviewer to increase the likelihood that the suspect will disclose crime relevant information4 that could be used against him or her in subsequent investigative and judicial processes. (p. 7) Positivity1, Successful Outcomes4 D1: The purpose of this contemporary comment is to build on this research by explicating more precisely the nature of rapport in interviews with criminal suspects […] (p. 1). [...] [I]nterrogative rapport—while similar in structure and process—differs in a fundamental way from rapport in other professional contexts (p. 6). D3: Gabbert et al. (2020) have coined the term ‘professional rapport’ to highlight the unique aspects of professional contexts in which rapport is built for temporary strategic purposes (e.g., investigative interviewing, therapeutic interventions). While an important distinction, we believe that a further step is necessary to account for the inherently adversarial function of rapport building within suspect interviews [...]. We therefore propose an alternative label, interrogative rapport [...]. (p. 7) 
Foster et al. (2022)  In the current study, the term “rapport” will be used and will be specifically examined and is considered to be the subjective experience between the interviewer and the interviewee [...]. (p. 2) No defining attributes. An interview necessarily invokes a subjective experience between an interviewer and interviewee. D1: [...]“[R]apport” [...] is considered to be the subjective experience between the interviewer and the interviewee [...]. (p. 2) 
Gabbert et al. (2021)  [...] [W]e propose [...] the term “professional rapport-building” [...]. Professional rapport-building can be understood as an intentional use of rapport behaviors to facilitate a positive interaction1 that may, or may not, lead to establishing genuine mutual2 rapport. (p. 2) Positivity1, Mutuality2 D3: Definitions of rapport are often vague and imprecise, thus leaving room for ambiguity in the ways in which they might be interpreted. For example, rapport has been defined as “The bond or connection between an investigative interviewer and interviewee” […]. “A state of communicative alliance” […], and a “Harmonious, empathetic, or sympathetic relation or connection to another self” […]. […] “A positive mood between interviewer and interviewee” […] and the establishment of a relationship, “which does not necessarily mean a friendly relationship” […]. Given the differences in the development of rapport in professional versus social contexts, we propose the idea that the term “professional rapport-building” is useful to describe the process of building rapport within a task-oriented professional interaction. (pp. 1 - 2) 
Hoekstra & Verhoeven (2021)  Rapport building during suspect interviewing is broadly defined as building a working relationship1 based on mutual2 understanding3, goals2, and needs2 [...]. (p. 4) Positivity1, Mutuality2, Communication3 D2: […] broadly defined as building a working relationship [...]. (p. 4) 
Marin & Gabbert (2022)  In investigative settings, rapport is synonymous with ‘operational accord’ which means that the interviewer creates a productive relationship1 based on cooperation4 and respect and in which the interviewee’s anxiety is minimised1 […]. (p. 3) Positivity1, Respect6, Successful Outcomes4 D1: In investigative settings, rapport is synonymous with ‘operational accord’ [...]. (p. 3) 
Nahouli et al. (2022)  Rapport is typically described as a ‘harmonious1, empathetic1, or sympathetic relation1 ‘or connection1 to another self’ […]. (p. 2) Positivity1 D1: Rapport is typically described [...]. (p. 2) 
Novotny et al. (2021)  Rapport is defined as a dyadic-level construct comprised of mutual attention2, positivity1, and coordination of behaviors during an interaction3 (Tickle-Degnen & Rosenthal, 1987, 1990). […] (p. 1) Positivity1, Mutuality2, Communication3 D1: [U]nder this definition [Tickle-Degnen & Rosenthal, 1987, 1990], only the complete combination of mutual attentiveness, positivity, and coordination constitutes an interaction in which rapport has been successfully developed. (p. 3) 
Tamm et al. (2021)  Rapport can be defined as the establishment of interpersonal trust5 between the interviewer and the interviewee, while communicating respect6, understanding3, and acceptance1 [...]. (p. 2) Positivity1, Communication3, Respect6, Trust5 None 
SourceDefinition of rapportaAttributes of definitionaDissociation strategy of definitionb
Brimbal et al. (2021)  Here we adopt a broad definition that characterizes the relationship between the interviewer and subject with a generally positive exchange1; attentiveness toward one another’s concerns1; and the importance of developing respect6 and trust5. (p. 56) Positivity1, Respect6, Trust5 D2: […] a broad definition that characterizes the relationship between the interviewer and subject. (p. 56) 
Crough et al. (2022)  [Interrogative Rapport:] [A] temporary working relationship1 created strategically by the interviewer to increase the likelihood that the suspect will disclose crime relevant information4 that could be used against him or her in subsequent investigative and judicial processes. (p. 7) Positivity1, Successful Outcomes4 D1: The purpose of this contemporary comment is to build on this research by explicating more precisely the nature of rapport in interviews with criminal suspects […] (p. 1). [...] [I]nterrogative rapport—while similar in structure and process—differs in a fundamental way from rapport in other professional contexts (p. 6). D3: Gabbert et al. (2020) have coined the term ‘professional rapport’ to highlight the unique aspects of professional contexts in which rapport is built for temporary strategic purposes (e.g., investigative interviewing, therapeutic interventions). While an important distinction, we believe that a further step is necessary to account for the inherently adversarial function of rapport building within suspect interviews [...]. We therefore propose an alternative label, interrogative rapport [...]. (p. 7) 
Foster et al. (2022)  In the current study, the term “rapport” will be used and will be specifically examined and is considered to be the subjective experience between the interviewer and the interviewee [...]. (p. 2) No defining attributes. An interview necessarily invokes a subjective experience between an interviewer and interviewee. D1: [...]“[R]apport” [...] is considered to be the subjective experience between the interviewer and the interviewee [...]. (p. 2) 
Gabbert et al. (2021)  [...] [W]e propose [...] the term “professional rapport-building” [...]. Professional rapport-building can be understood as an intentional use of rapport behaviors to facilitate a positive interaction1 that may, or may not, lead to establishing genuine mutual2 rapport. (p. 2) Positivity1, Mutuality2 D3: Definitions of rapport are often vague and imprecise, thus leaving room for ambiguity in the ways in which they might be interpreted. For example, rapport has been defined as “The bond or connection between an investigative interviewer and interviewee” […]. “A state of communicative alliance” […], and a “Harmonious, empathetic, or sympathetic relation or connection to another self” […]. […] “A positive mood between interviewer and interviewee” […] and the establishment of a relationship, “which does not necessarily mean a friendly relationship” […]. Given the differences in the development of rapport in professional versus social contexts, we propose the idea that the term “professional rapport-building” is useful to describe the process of building rapport within a task-oriented professional interaction. (pp. 1 - 2) 
Hoekstra & Verhoeven (2021)  Rapport building during suspect interviewing is broadly defined as building a working relationship1 based on mutual2 understanding3, goals2, and needs2 [...]. (p. 4) Positivity1, Mutuality2, Communication3 D2: […] broadly defined as building a working relationship [...]. (p. 4) 
Marin & Gabbert (2022)  In investigative settings, rapport is synonymous with ‘operational accord’ which means that the interviewer creates a productive relationship1 based on cooperation4 and respect and in which the interviewee’s anxiety is minimised1 […]. (p. 3) Positivity1, Respect6, Successful Outcomes4 D1: In investigative settings, rapport is synonymous with ‘operational accord’ [...]. (p. 3) 
Nahouli et al. (2022)  Rapport is typically described as a ‘harmonious1, empathetic1, or sympathetic relation1 ‘or connection1 to another self’ […]. (p. 2) Positivity1 D1: Rapport is typically described [...]. (p. 2) 
Novotny et al. (2021)  Rapport is defined as a dyadic-level construct comprised of mutual attention2, positivity1, and coordination of behaviors during an interaction3 (Tickle-Degnen & Rosenthal, 1987, 1990). […] (p. 1) Positivity1, Mutuality2, Communication3 D1: [U]nder this definition [Tickle-Degnen & Rosenthal, 1987, 1990], only the complete combination of mutual attentiveness, positivity, and coordination constitutes an interaction in which rapport has been successfully developed. (p. 3) 
Tamm et al. (2021)  Rapport can be defined as the establishment of interpersonal trust5 between the interviewer and the interviewee, while communicating respect6, understanding3, and acceptance1 [...]. (p. 2) Positivity1, Communication3, Respect6, Trust5 None 

Note. aSuperscripts track the attributes featured in a definition. bBold text flags markers of dissociation.

Table 2 makes it evident that the definitions are not identical: they ascribe rapport with different attributes. Which of those supposedly real definitions should be the standard reference when assessing construct validity? There is currently no basis to give any definition the standard reference status. That is why the sentiment “rapport is difficult to define” remains a refrain in the literature. The expression—rapport—is ingrained in investigative interviewing research. A suggestion to discontinue its use would go unheeded. But the literature needs a univocal definition to maintain objectivity for construct validity’s sake.

Next, I expand on the pitfalls of pursuing a real definition of rapport and why a nominal definition offers a pragmatic solution, given the literature’s state.

It is incontrovertible that the notion of rapport is ambiguous by default. Other research domains, not just investigative interviewing, use rapport in different senses. For example, analysts in the field of communication research have long since lamented that rapport encompasses a wide variety of relational formulations (e.g., Jorgenson, 1992). The tendency for the word to elicit different interpretations disguises the challenge that troubles us as one real definition can solve—because real definition presents a false hope of bringing objectivity. In what follows, I will explain why nominal definition is a more objective approach and can better address the challenge of restoring clarity better than real definition can.

Nothing can provide a literal point of comparison to ascertain the veracity of any given definition. As Abelson (1967) notes, if we cannot observe an abstract notion, we cannot establish that a definition necessarily captures that idea. Analysts cannot implement a perspective-independent method to verify whether any corresponding real definition of rapport, in fact, resembles something in the ether called rapport. That mirage leads well-intentioned research projects to continue stipulating real definitions, hoping that they might capture what rapport truly is. Such pursuits of real definition have riddled the literature with numerous definitions, rendering the word rapport meaningless in the investigative interviewing literature. According to the review by Neequaye and Mac Giolla (2022), at least 22 unique definitions exist.

Nominal definition will rectify the limitations of inconsistency with which real definition has plagued the literature. Stakeholders must determine what the word rapport is to mean as far as investigative interviewing is concerned. And the nominated definition must outline the values and properties stakeholders consider crucial and why. Examples of values include—Should rapport concern the human rights of interviewees? Should the word refer to congeniality? Or should it cover a range of set values? And the matter of property arises when considering directionality.2 Should rapport concern attributes that naturally emerge between interactants (e.g., “the subjective experience between the interviewer and the interviewee”: Foster et al., 2022)? Or should rapport focus on attributes of the interviewer’s approach to conducting an interview (e.g., “[A] temporary working relationship created strategically by the interviewer: Crough et al., 2022”)? Let us abandon the fiction that we can arrive at a rapport definition without acknowledging that definitions legislate what stakeholders consider acceptable in a given context. Whenever authors posit a definition, they prescribe ideals they believe should characterize the interaction between an interviewer and interviewee. Consider the following definitions.

“Rapport can be defined as the establishment of interpersonal trust between the interviewer and the interviewee, while communicating respect, understanding, and acceptance (Tamm et al., 2021).”

“Rapport is typically described as a ’harmonious, empathetic, or sympathetic relation ’or connection to another self (Nahouli et al., 2022).”

According to Tamm et al.’s (2021) definition, interpersonal trust, respect, understanding, and acceptance are the critical ideals that should characterize rapport. And Nahouli et al. (2022) subscribe to harmony, empathy, and connection. We do the literature a disservice when we present such recommendations as though they are facts, like the date of a historical event. Definitions are choices—temporary agreements about how language users understand terms (Robinson, 1963; Schiappa, 1993). And a rapport definition should be approached accordingly—a temporary agreement on what investigative interviewing researchers and practitioners want rapport to mean.

By temporary agreement, I do not mean to suggest that we should entertain multiple nominal rapport definitions at once. Multiple nominal definitions would likely perpetuate ambiguity. An essential advantage of nominal definition is that the approach is pragmatic and stands a better chance of leading to consensus about what stakeholders want rapport to mean. I use the phrase temporary agreement to emphasize that stakeholders can continue to debate any nominal definition that achieves consensus status, subjecting it to scrutiny and necessary adjustment to improve. That ethos of nominal definition offers the advantage real definition lacks when defining abstract concepts. Real definition assumes to have flagged an objective thing, stifling further debate. But nominal definition is a temporary agreement that leaves room for refinement if necessary. That flexibility of nominal definition makes it more amenable to facilitating consensus.

The recommendation to nominate a rapport definition likely to embody consensus ideals might invite objections. I will flag and address some of those counterarguments that can arise. Note that the following discussion concerns the investigative interviewing literature.

A critic might say: “the call to simply nominate a single sense to use the word rapport is arbitrary”. The objective way to arrive at a definition is by some form of scientific analysis or synthesis with rigor.” For example, Duke (2013) reviewed the literature to identify attributes representing rapport.3 That counterargument supposes stakeholders must conduct experiments, survey experts, or review the relevant literature to define rapport.

The objection just described fails to distinguish a method of formulating a definition from the purpose of designating that definition. Stakeholders might be unsure of consensus ideals or want to ascertain those ideals. Experiments or literature reviews could assist in arriving at ideals stakeholders would agree with—to form an acceptable definition. But let us not lose sight of the fact that analysis or synthesis are methods to achieve the objective of uncovering ideals. Whatever method one chooses to flag ideals will necessarily produce a choice—a nominal definition. When we fail to recognize the distinction between method and purpose, we allow the illusion that certain methods generate real definitions when, in truth, methods are tools that assist in nominating definitions.

One could ask this question to disagree with a pragmatic approach to a rapport definition. “How can we prove we have captured rapport if we nominate a definition?” As discussed, stakeholders can use scientific methods to assist with a nomination. The idea that one needs to prove a definition captures some abstract notion is yet another illusion vitalized by the folly of real definition (Robinson, 1963). Let us not forget that there is no literal point of comparison to ascertain that one definition is more rapport-like than any other. Of course, different people might find some definitions more reasonable than others. Such disagreements come down to preference, not objective reality.

The charge to prove a rapport definition implicitly suggests that the word naturally denotes a single sense. But it is evident that rapport elicits different interpretations from various authors. The objective to demonstrate that any definition is the best copy of something called rapport cannot succeed when no literal point of comparison exists. The issue to prove is whether a choice of nominal definition can or has achieved consensus status among a community of language users. Real definitions of rapport pitch themselves as descriptions of objective reality—but such definitions cannot be tested to ascertain their verisimilitude, given rapport’s abstractness. Conversely, nominal definitions would indicate the current preference of language users—whether stakeholders hold such preference can be verified.

Preempting Definitions that Invite Circular and Unfalsifiable Hypotheses

The primary goals of investigative interviewing comprise the need for interviewers to conduct themselves ethically and elicit information relevant to an investigation (e.g., Brandon, 2014; Vrij et al., 2017). It is essential not to mistake those objectives as definitions of rapport or include those goals in a definition. Such oversight invites circular and unfalsifiable hypotheses, and definitions with that feature already exist in the literature. For example: “a working relationship between operator [an interviewer] and source [an interviewee] based on a mutually shared understanding of each other’s goals and needs—that can lead to successful actionable intelligence or information [emphasis added] (Kelly et al., 2013)”.

Two blind spots accompany definitions with the limitation just described. (1) They prevent analysts from designing the appropriate studies to examine rapport’s correlates. That limitation makes it impossible to refute rapport’s presumed effects. Suppose a manipulation fails to generate the outcomes contained in a definition, like actionable intelligence, as included in Kelly et al.’s (2013) definition. Then, one could claim the operationalization insufficiently instantiated rapport. That loophole consistently shifts the goalpost. Analysts can never question the definition’s ability to produce the correlates of interest. (2) Definitions containing circular claims make an idea necessary before analysts can examine whether that importance is warranted. Definitions claiming that rapport makes interviewing ethical or elicits relevant information well-nigh conclude research on rapport: there is nothing left to examine.

This article draws attention to the ambiguity of rapport in the investigative interviewing literature via a conceptual analysis explaining the limitations of pursuing real definitions. The question “what is rapport?” continues to baffle researchers and practitioners due to the proliferation of and search for real definitions. And because there is no literal point of comparison, different authors use the word in different senses, assuming (implicitly or explicitly) they have captured the real thing. We can escape that quagmire using a practical approach via a nominal definition, which embodies ideals or values the majority of stakeholders will accept. Such a definition can be achieved while maintaining scientific rigor. Stakeholders must nominate a single sense in which to use the word rapport.

A critic might take issue with this review’s methodology with this objection: some publications are missing due to the focus on the most recent articles. To the best of my knowledge, this review includes all articles published on rapport in investigative interviewing within security settings (August 2021 – January 2023). Besides, Neequaye and Mac Giolla’s (2022) review highlights similar ambiguities in the remainder of the literature. Even if one grants the unwarranted concession that this review misses critical publications, the limitation this review flags would still be concerning. Multiple and different definitions continue to drive most of the latest research, perpetuating conceptual ambiguity. Relatedly, one could argue that this review should have analyzed methods authors use in measuring rapport. But such an analysis would be a fruit of a poisonous tree. I focused on definitions because definitional limitations call measurement into question by default (e.g., Flake & Fried, 2020). It is challenging, if not impossible, to offer an objective or fair analysis of suited methods and construct validity if confusion surrounds the term stakeholders want to measure.

The question “what is rapport?” will cease being a headache if stakeholders make a concerted effort to arrive at a consensus definition. Such consensus will provide a standard to assess operationalizations claiming to examine rapport and its correlates. A nominal definition stands the best chance of bringing the clarity the investigative interviewing literature needs on rapport.

There are no conflicts of interest to declare.

All data supporting the findings in this research are publicly available publications, and the present manuscript contains the pertinent aspects.

1.

Interested readers can consult Neequaye and Mac Giolla (2022) for a complete discussion of the attributes.

2.

Many thanks to Fiona Gabbert for drawing my attention to this issue.

3.

Note that this work did not mention that the endeavor was to define rapport. I flag it for the purpose of illustration.

Abelson, R. (1967). Definition. In P. Edwards (Ed.), The Encyclopedia of Philosophy (Vol. 2, pp. 314–324). Macmillan.
Alison, L., & Alison, E. (2017). Revenge versus rapport: Interrogation, terrorism, and torture. American Psychologist, 72(3), 266–277. https://doi.org/10.1037/amp0000064
Brandon, S. E. (2014). Towards a Science of Interrogation. Applied Cognitive Psychology, 28(6), 945–946. https://doi.org/10.1002/acp.3090
Brimbal, L., Meissner, C. A., Kleinman, S. M., Phillips, E. L., Atkinson, D. J., Dianiska, R. E., Rothweiler, J. N., Oleszkiewicz, S., & Jones, M. S. (2021). Evaluating the benefits of a rapport-based approach to investigative interviews: A training study with law enforcement investigators. Law and Human Behavior, 45(1), 55–67. https://doi.org/10.1037/lhb0000437
Crough, Q., Dion Larivière, C., Snow, M. D., & Eastwood, J. (2022). Reflections on the nature of rapport within suspect interviews. Current Issues in Criminal Justice, 34(2), 219–228. https://doi.org/10.1080/10345329.2021.2018814
Dando, C., Taylor, D. A., Caso, A., Nahouli, Z., Adam, C. (2022). Interviewing in virtual environments: Towards understanding the impact of rapport-building behaviours and retrieval context on eyewitness memory. Memory Cognition, 51(2), 404–421. https://doi.org/10.3758/s13421-022-01362-7
David, G. C., Rawls, A. W., Trainum, J. (2018). Playing the Interrogation Game: Rapport, Coercion, and Confessions in Police Interrogations. Symbolic Interaction, 41(1), 3–24. https://doi.org/10.1002/symb.317
Dianiska, R. E., Swanner, J. K., Brimbal, L., Meissner, C. A. (2021). Using disclosure, common ground, and verification to build rapport and elicit information. Psychology, Public Policy, and Law, 27(3), 341–353. https://doi.org/10.1037/law0000313
Duke, M. C. (2013). The Development of the Rapport Scales for Investigative Interviews and Interrogations [Ph.D., The University of Texas at El Paso]. ProQuest Dissertations and Theses. http://www.proquest.com/docview/1418015989/abstract/8C36CB36043047DEPQ/1
Flake, J. K., Fried, E. I. (2020). Measurement Schmeasurement: Questionable Measurement Practices and How to Avoid Them. Advances in Methods and Practices in Psychological Science, 3(4), 456–465. https://doi.org/10.1177/2515245920952393
Foster, I., Talwar, V., Crossman, A. (2022). The role of rapport in eliciting children’s truthful reports. Applied Developmental Science, 27(3), 221–237. https://doi.org/10.1080/10888691.2022.2058507
Gabbert, F., Hope, L., Luther, K., Wright, G., Ng, M., Oxburgh, G. (2021). Exploring the use of rapport in professional information-gathering contexts by systematically mapping the evidence base. Applied Cognitive Psychology, 35(2), 329–341. https://doi.org/10.1002/acp.3762
Hagsand, A. V., Kelly, C. E., Mindthoff, A., Evans, J. R., Compo, N. S., Karhu, J., Huntley, R. (2022). The interrogator-suspect dynamic in custodial interrogations for high-stakes crimes in Sweden: An application of the interrogation taxonomy framework. Scandinavian Journal of Psychology, 64(3), 352–367. https://doi.org/10.1111/sjop.12889
Hoekstra, M. R., Verhoeven, W.-J. (2021). Investigative interviewing of high-status fraud suspects. Journal of Investigative Psychology and Offender Profiling, 18(3), 185–200. https://doi.org/10.1002/jip.1579
Hoogesteyn, K., Verigin, B. L., Finnick, D., Meijer, E. H. (2023). Rapport-building: Chat versus in-person witness interviews. Journal of Investigative Psychology and Offender Profiling, 20(2), 162–178. https://doi.org/10.1002/jip.1609
Hwang, H. C., Matsumoto, D. (2020). The effects of liking on informational elements in investigative interviews. Journal of Investigative Psychology and Offender Profiling, 17(3), 280–295. https://doi.org/10.1002/jip.1556
Izotovas, A., Kelly, C., Walsh, D. (2021). The Domains of PEACE: Examining Interviews with Suspected Sex Offenders. Journal of Police and Criminal Psychology, 36(4), 743–757. https://doi.org/10.1007/s11896-021-09465-8
Jorgenson, J. (1992). Communication, Rapport, and the Interview: A Social Perspective. Communication Theory, 2(2), 148–156. https://doi.org/10.1111/j.1468-2885.1992.tb00034.x
Kelly, C. E., Miller, J. C., Redlich, A. D., Kleinman, S. M. (2013). A taxonomy of interrogation methods. Psychology, Public Policy, and Law, 19(2), 165–178. https://doi.org/10.1037/a0030310
Klein, G., Klein, H. A., Lande, B., Borders, J., Whitacre, J. C. (2015). Police and Military as Good Strangers. Journal of Occupational and Organizational Psychology, 88(2), 231–250. https://doi.org/10.1111/joop.12110
Marin, A., Gabbert, F. (2022). The use of self-disclosure to build rapport with mock covert human intelligence sources (CHIS). Journal of Policing, Intelligence and Counter Terrorism, 18(2), 158–173. https://doi.org/10.1080/18335330.2022.2108331
Matsumoto, D., Hwang, H. C. (2021). An initial investigation into the nature and function of rapport in investigative interviews. Applied Cognitive Psychology, 35(4), 988–998. https://doi.org/10.1002/acp.3825
Nahouli, Z., Dando, C. J., Mackenzie, J.-M., Aresti, A. (2021). Rapport building and witness memory: Actions may ‘speak’ louder than words. PLOS ONE, 16(8), e0256084. https://doi.org/10.1371/journal.pone.0256084
Nahouli, Z., Mackenzie, J.-M., Aresti, A., Dando, C. (2022). Rapport building with offenders in probation supervision: The views of English probation practitioners. Probation Journal, 70(2), 104–123. https://doi.org/10.1177/02645505221137448
Neequaye, D. A., Mac Giolla, E. (2022). The Use of the Term Rapport in the Investigative Interviewing Literature: A Critical Examination of Definitions. Meta-Psychology, 6. https://doi.org/10.15626/mp.2021.2808
Novotny, E., Frank, M. G., Grizzard, M. (2021). A Laboratory Study Comparing the Effectiveness of Verbal and Nonverbal Rapport-Building Techniques in Interviews. Communication Studies, 72(5), 819–833. https://doi.org/10.1080/10510974.2021.1975141
Richardson, B. H., Nash, R. A. (2021). ‘Rapport myopia’ in investigative interviews: Evidence from linguistic and subjective indicators of rapport. Legal and Criminological Psychology, 27(1), 32–47. https://doi.org/10.1111/lcrp.12193
Robinson, R. (1963). Definition. Oxford University Press. https://doi.org/10.1093/acprof:oso/9780198241607.001.0001
Schiappa, E. (1993). Arguing about definitions. Argumentation, 7(4), 403–417. https://doi.org/10.1007/bf00711058
Tamm, A., Otzipka, J., Volbert, R. (2021). Assessing the Individual Interviewer Rapport-Building and Supportive Techniques of the R-NICHD Protocol. Frontiers in Psychology, 12, 659438. https://doi.org/10.3389/fpsyg.2021.659438
Vrij, A., Meissner, C. A., Fisher, R. P., Kassin, S. M., Morgan, C. A., III, Kleinman, S. M. (2017). Psychological Perspectives on Interrogation. Perspectives on Psychological Science, 12(6), 927–955. https://doi.org/10.1177/1745691617706515
Wilson, M., Matsumoto, D., Avendano Vasquez, A. N., Garcia Garcla, J. M., Helmy, M. (2022). Social Judgments of Rapport in Investigative Interviews Across Cultures. Cross-Cultural Research, 56(5), 496–526. https://doi.org/10.1177/10693971221119944
This is an open access article distributed under the terms of the Creative Commons Attribution License (4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Supplementary data