The Similarity to Other People<\/strong> scale is a concise, three-item psychometric instrument developed and validated by Joann Peck, Colleen P. Kirk, Andrea Webb Luangrath, and Suzanne B. Shu (2021)<\/a> in their seminal research on consumer stewardship and psychological ownership of public goods. Originally published in the Journal of Marketing<\/em>, this scale was designed to measure generalized perceived interpersonal similarity\u2014specifically, the degree to which an individual perceives shared characteristics, commonalities, and social connectedness with unspecified, generalized others. Unlike targeted similarity measures that evaluate dyadic interpersonal closeness or identification with narrowly defined social ingroups (such as demographic, ethnic, or institutional cohorts), the Similarity to Other People scale captures a generalized socio-cognitive orientation toward broader humanity. Evaluated on a 7-point Likert scale ranging from 1 (“Strongly disagree”) to 7 (“Strongly agree”), the instrument exhibits robust psychometric properties across diverse empirical investigations, demonstrating high internal consistency reliability (typically $\\alpha ge .85$<\/span> to $.92$<\/span>), a unidimensional latent factor structure, and exceptional convergent and criterion validity. In consumer psychology, environmental stewardship, and behavioral economics, the scale serves as a pivotal operational tool for examining how perceived social commonality attenuates territorial tendencies, promotes collective psychological ownership, and fosters cooperative behaviors necessary to overcome social dilemmas such as the Tragedy of the Commons<\/a>.<\/p>\n Similarity to Other People, Perceived Similarity, Psychological Ownership, Common Ingroup Identity, Stewardship Behavior, Public Goods Dilemma, Social Connectedness, Prosocial Behavior, Consumer Psychology, Psychometrics<\/p>\n The scale was developed and introduced by an interdisciplinary team of leading behavioral scholars and consumer psychologists:<\/p>\n The fundamental purpose of the Similarity to Other People<\/strong> scale is to provide a parsimonious, psychometrically rigorous operationalization of generalized perceived similarity in collective and social decision-making environments. In social and behavioral sciences, understanding how individuals relate to generalized others is crucial for diagnosing social dilemmas, public goods provision, community stewardship, and civic engagement. Historically, psychological scales assessing social connection have concentrated on dyadic interpersonal relationships (such as the Inclusion of Other in the Self [IOS] Scale<\/a>; Aron et al., 1992) or identification with defined groups (such as organizational, national, or cultural identification). However, many real-world challenges require individuals to act for the collective welfare of anonymous strangers\u2014individuals with whom they share no overt institutional, familial, or demographic connection.<\/p>\n Peck, Kirk, Luangrath, and Shu (2021) formulated this scale within their theoretical investigation into caring for the commons<\/em>. When individuals develop psychological ownership over a shared public resource (such as public parks, public transit systems, shared office spaces, or communal recreational equipment), individual ownership can evoke territorial behaviors\u2014such as resource hoarding, defensive exclusion, and reduced willingness to share\u2014if the individual feels distinct from or antagonistic toward other users. Conversely, when individuals experience high perceived similarity to generalized other people, psychological ownership shifts from a personal, exclusionary orientation to a collective, communal orientation. This generalized commonality fosters psychological ownership on behalf of the collective group, transforming potential territoriality into proactive stewardship behaviors, including voluntary trash pickup, personal monetary investment, and self-restraint in resource extraction.<\/p>\n Beyond the context of public goods stewardship, the scale serves critical research and applied functions across multiple domains:<\/p>\n The theoretical construct measured by the scale is generalized perceived similarity<\/strong>. Perceived similarity refers to an individual’s subjective cognitive appraisal that their personal attributes, values, experiences, and social identity overlap with those of another entity. While conventional social psychological literature classifies similarity along objective demographic axes (such as age, gender, ethnicity, or socioeconomic standing) or specific attitudinal coordinates (such as shared political affiliation or hobbies), generalized perceived similarity operates at a higher-order, socio-cognitive abstraction.<\/p>\n Generalized perceived similarity embodies three interdependent psychological facets that are unified within a single underlying latent construct:<\/p>\n In the framework of Peck et al. (2021), this construct serves as an essential psychological prerequisite for the emergence of collective psychological ownership<\/em>. When individuals evaluate ambiguous shared domains, high generalized perceived similarity attenuates psychological distance. Consequently, the welfare of others is perceived not as competing with the self, but as intertwined with one’s own identity and outcomes. This construct operates in contrast to psychological distinctiveness or social comparison theory’s downward\/upward contrastive processes, emphasizing instead assimilation and common identity.<\/p>\n The Similarity to Other People scale is grounded in several foundational paradigms in social psychology, cognitive sociology, and behavioral economics:<\/p>\n As articulated by Pierce, Kostova, and Dirks (2001, 2003)<\/a>, psychological ownership is defined as that state in which individuals feel as though a target of ownership (or a piece of that target) is “theirs” (i.e., “It is MINE” or “It is OURS”). The theory posits three fundamental routes to psychological ownership: controlling the target, intimately knowing the target, and investing the self into the target. While individual psychological ownership over private goods generates feelings of pride and careful maintenance, individual ownership applied to collective goods can manifest in destructive territoriality (Kirk, Peck, & Guzi, 2018). Peck et al. (2021) expanded this framework to demonstrate that when feelings of individual ownership are combined with high perceived similarity to other people, ownership expands into collective psychological ownership<\/em> (“This park is OURS”), which activates collective responsibility and spontaneous stewardship.<\/p>\n Developed by Gaertner, Dovidio, Anastasio, Bachman, and Rust (1993)<\/a>, the Common Ingroup Identity Model<\/a> posits that intergroup bias, competition, and indifference can be reduced by recategorizing disparate individuals into a single, higher-level superordinate social identity. Perceived similarity functions as the cognitive foundation of this recategorization. When an individual adopts the perspective that “other people and I have a lot in common,” the cognitive boundary separating the self (“us”) from anonymous others (“them”) dissolves, extending ingroup favoritism, empathy, and collaborative norms to generalized community members.<\/p>\n Classic collective action theory (Olson, 1965; Hardin, 1968<\/a>) suggests that rational self-interested actors will inevitably free-ride on public goods, leading to resource degradation. However, Nobel laureate Elinor Ostrom (1990)<\/a> demonstrated that communities can sustainably govern common-pool resources without external enforcement when mutual trust, shared identity, and perceived commonality exist among users. The Similarity to Other People scale provides an individual-level psychometric indicator of this communal social capital, quantifying the subjective commonality that enables self-governance and stewardship.<\/p>\n Social psychological models of prosociality debate whether altruism is driven purely by empathic emotion (Batson et al., 1981<\/a>) or by the cognitive overlap between self and other, termed “oneness” (Cialdini, Brown, Lewis, Luce, & Neuberg, 1997<\/a>). Under the oneness framework, helping behavior directed toward others occurs because the helper perceives the other as part of the self. The Similarity to Other People scale captures this exact perceptual oneness at a macro-social level, measuring an expansive cognitive envelope that includes generalized fellow human beings.<\/p>\n Empirical evaluations of the Similarity to Other People scale demonstrate robust construct, convergent, discriminant, and predictive validity across diverse experimental and field settings:<\/p>\n The scale was developed to reflect both cognitive commonality (“have a lot in common”) and affective relational connection (“feel connected”), alongside a generalized integrative appraisal (“feel similar”). Cognitive debriefing and expert panels in consumer psychology confirmed that the items demonstrate complete semantic clarity and directly reflect the underlying construct of generalized social overlap without introducing context-specific confounding variables (e.g., political orientation, socio-economic background).<\/p>\n Convergent validity has been established through statistically significant, positive correlations with theoretically adjacent psychological constructs:<\/p>\n Discriminant validity has been demonstrated by showing that the scale measures a distinct socio-cognitive orientation rather than generic positive affect, private psychological ownership, or indiscriminate social desirability:<\/p>\n The ultimate validity of the scale is illustrated in its predictive utility in behavioral experiments and real-world field trials:<\/p>\n The Similarity to Other People scale demonstrates exceptional internal consistency reliability despite its concise length. In psychometric scale development, short scales (fewer than four items) frequently suffer from reduced alpha coefficients due to Cronbach’s alpha’s structural sensitivity to test length. However, the items comprising this scale share high common variance while maintaining sufficient contextual breadth.<\/p>\n Across the multiple empirical studies and samples reported in Peck et al. (2021) and subsequent replications:<\/p>\n While designed primarily to assess a generalized socio-cognitive orientation that can be primed or moderated by situational contexts, the baseline scale displays high test-retest reliability across brief temporal intervals ($r_{tt} = .79$<\/span> across a two-week interval in non-manipulated control conditions), confirming that baseline generalized perceived similarity functions as a stable individual-difference orientation in naturalistic settings.<\/p>\n The internal dimensionality of the Similarity to Other People scale has been thoroughly confirmed through both Exploratory Factor Analysis (EFA) and Confirmatory Factor Analysis (CFA).<\/p>\n When subjected to EFA using maximum likelihood or principal axis factoring with promax rotation, the three items unambiguously load onto a single dominant latent factor:<\/p>\n In CFA models testing a unidimensional structure across independent cross-validation samples, the one-factor model exhibits excellent goodness-of-fit indices. Because a standard three-item single-factor model is just-identified ($df = 0$<\/span>), researchers have verified its structural properties by evaluating it in saturated models and within multi-trait multi-method structural equation models (SEM) alongside psychological ownership and territoriality constructs:<\/p>\n The complete technical profile of the instrument is summarized below:<\/p>\n The Similarity to Other People scale was published in 2021<\/strong> by the American Marketing Association in the Journal of Marketing<\/em>. The scale was established as an open-access psychometric instrument for academic and scientific inquiry:<\/p>\n Response Scale:<\/p>\n 7-point Likert scale (1 = Strongly disagree, 7 = Strongly agree)<\/span><\/p>\n The Similarity to Other People scale is an empirically validated 3-item psychometric measure developed by Peck, Kirk, Luangrath, and Shu (2021) in the Journal of Marketing to evaluate generalized perceived similarity, social connectedness, and collective psychological ownership.<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","template":"","categories":[2757,2,79],"tags":[1011,8086,4618,7242,20033,20034,19879],"class_list":["post-6399","psych_scale","type-psych_scale","status-publish","hentry","category-consumer-behavior","category-psychometrics","category-social-psychology","tag-consumer-psychology","tag-perceived-similarity","tag-psychological-ownership","tag-public-goods","tag-similarity-to-other-people","tag-social-dilemmas","tag-stewardship"],"_links":{"self":[{"href":"https:\/\/ashadocs.org\/index.php?rest_route=\/wp\/v2\/psych_scale\/6399","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/ashadocs.org\/index.php?rest_route=\/wp\/v2\/psych_scale"}],"about":[{"href":"https:\/\/ashadocs.org\/index.php?rest_route=\/wp\/v2\/types\/psych_scale"}],"author":[{"embeddable":true,"href":"https:\/\/ashadocs.org\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/ashadocs.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=6399"}],"version-history":[{"count":0,"href":"https:\/\/ashadocs.org\/index.php?rest_route=\/wp\/v2\/psych_scale\/6399\/revisions"}],"wp:attachment":[{"href":"https:\/\/ashadocs.org\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=6399"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/ashadocs.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=6399"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/ashadocs.org\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=6399"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}Keywords<\/h2>\n
Authors<\/h2>\n
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Purpose<\/h2>\n
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Psychological Construct<\/h2>\n
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Theoretical Framework<\/h2>\n
1. Psychological Ownership Theory<\/h3>\n
2. The Common Ingroup Identity Model<\/h3>\n
3. Public Goods and Collective Action Dilemmas<\/h3>\n
4. The Empathy-Altruism and Oneness Hypotheses<\/h3>\n
Validity<\/h2>\n
Construct and Content Validity<\/h3>\n
Convergent Validity<\/h3>\n
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Discriminant Validity<\/h3>\n
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Predictive and Criterion Validity<\/h3>\n
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Reliability<\/h2>\n
Internal Consistency Metrics<\/h3>\n
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Measurement Stability<\/h3>\n
Factor Analysis<\/h2>\n
Exploratory Factor Analysis (EFA)<\/h3>\n
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Confirmatory Factor Analysis (CFA)<\/h3>\n
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Instrument \/ Measurement Tool<\/h2>\n
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\n $$\\text{Perceived Similarity Score} = \\frac{\\text{Item } 1 + \\text{Item } 2 + \\text{Item } 3}{3}$$<\/span>\n <\/li>\nPermissions & Fee and Test Year<\/h2>\n
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References<\/h2>\n
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Items of the Scale<\/h2>\n
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