Generalized Belief Measure (GBM)

Abstract

The Generalised Belief Measure (GBM) is a highly adaptable psychological instrument designed by James C. McCroskey to quantify an individual’s belief regarding any specific topic or proposition. Unlike scales restricted to a single construct, the GBM is context-free, allowing its application across a broad spectrum of subjects in communication research and social science studies. The measure employs a 7-point semantic differential format using bipolar adjective pairs to capture the intensity and valence of the belief, yielding high internal consistency and strong evidence of validity, including strong face, concurrent, and predictive validity.

Keywords

Generalised Belief Measure, McCroskey, belief measurement, communication research, attitude scale, semantic differential, psychometrics.

Authors

McCroskey, J. C.

Purpose

The primary purpose of the Generalised Belief Measure (GBM) is to provide a flexible, reliable, and valid means of assessing any target belief statement. This instrument was specifically developed to transcend the limitations of topic-specific scales, enabling researchers to measure beliefs concerning a wide variety of subjects—ranging from political issues (e.g., “Federal Taxes Should be Reduced”) to social norms (e.g., “Capital Punishment”).

Its generalized nature makes it particularly valuable for studies in persuasive communication, where the central focus is often on assessing the strength and direction of a recipient’s pre-existing belief before and after exposure to a message. The GBM ensures consistency in measurement methodology regardless of the specific content being evaluated, making it a foundational tool in communication research.

Construct

The core psychological construct measured by the GBM is the intensity and valence of an individual’s specific, targeted belief. In the context of communication theory, beliefs are often viewed as subjective probabilities concerning the relationship between two or more objects or concepts, reflecting an evaluative judgment.

The GBM operationalizes this construct using a semantic differential approach, which is classically associated with measuring the connotative meaning of concepts. By applying six bipolar adjective pairs (e.g., Good/Bad, Right/Wrong) directly to a target belief statement, the GBM captures the affective and evaluative dimensions that constitute the strength of that belief across contexts.

Validity

The GBM demonstrates strong evidence of psychometric soundness across multiple dimensions of validity. Specifically, the measure reports strong face validity, meaning the items appear relevant and appropriate for measuring the intended construct of belief strength and evaluation to both experts and respondents.

Furthermore, the instrument exhibits strong concurrent validity, indicating that scores obtained on the GBM align well with other established measures of related constructs administered simultaneously. Crucially, it possesses strong predictive validity, suggesting that scores on the GBM are effective in forecasting related behaviors or outcomes, which is particularly critical in studies focusing on behavioral intent resulting from belief change.

Reliability

The reliability of the Generalised Belief Measure is consistently reported as excellent, reflecting high internal consistency. Studies utilizing the GBM routinely yield Cronbach’s alpha estimates exceeding the strong threshold of 0.90, often reaching 0.92 or higher. This high level of reliability indicates that the six items within the scale measure the same underlying evaluative dimension of the target belief with great homogeneity.

This robust reliability is a key feature that supports the GBM’s widespread application across diverse research contexts where measurement precision is paramount. Researchers utilizing the GBM are generally advised to expect and verify an alpha reliability estimate above 0.90 in their specific samples to confirm the measure’s consistency in their context.

Factor Analysis

Although the GBM is designed for generalized use across contexts, the exceptionally high Cronbach’s alpha values reported (consistently above 0.90) strongly suggest that the scale operates as a single, highly cohesive factor structure in relation to any given target belief. The instrument is intended to measure the overall evaluative response (the strength and valence of the belief) rather than multiple distinct dimensions of the belief object.

Therefore, typical factor analyses of the GBM are expected to confirm a unidimensional structure, where all six semantic differential items load highly onto a single factor representing the holistic, overall evaluation of the target statement. This unidimensionality is essential for its function as a reliable, generalized measure of belief strength.

Instrument

Test Type: Semantic Differential Scale / Generalized Belief/Attitude Measure

Format: 7-point bipolar adjective scale (6 items)

Language Available: English (Primary)

Population Group: General Population / Adults

Age Group: Adolescents and Adults (typically 16+)

Population Details: Applicable to any population capable of understanding the target belief statement and the bipolar adjective pairs, making it highly flexible for diverse research settings.

Test Methodology: Respondents indicate their feelings about a specified target belief (which must be clearly stated, e.g., “Federal Taxes Should be Reduced”) by selecting one number between the opposing adjective pairs on a 7-point scale. The scale anchors 1 and 7 represent very strong feelings, 2 and 6 strong feelings, 3 and 5 fairly weak feelings, and 4 indicates indecision or lack of understanding.

Keywords

McCroskey, generalized scale, predictive validity, concurrent validity, internal consistency, 7-point scale, communication research tool.

Authors

Author ORCID Identifier: Not specified in primary sources.

Affiliation Email addresses: Not specified in primary sources.

Correspondence Address: Not specified in primary sources.

Permissions & Fee and Test Year

The Generalised Belief Measure (GBM) was developed and documented primarily in the mid-1990s, with key references dating to 1996. The full psychometric description was later consolidated in 2006. Specific permission requirements and associated fees for academic research use should be verified directly with the author, James C. McCroskey, or the publisher of the foundational texts (Waveland Press).

As a widely published and referenced academic instrument, the GBM is often available for non-commercial educational or research purposes, although official authorization should always be sought for formal studies.

Reference’s

• McCroskey, J. C., & Richmond, V. P. (1996). Fundamentals of human communication: An interpersonal perspective. Prospect Heights, IL: Waveland Press.
• McCroskey, J. C. (2006). An introduction to communication research: The Generalised Belief Measure (GBM). The original PDF can be downloaded here: https://www.jamescmccroskey.com/gim/Psychometric_Description_of_GBM_Scale.pdf

Items of the Generalised Belief Measure (GBM)

Directions: On the scales below, please indicate your feelings about “Capital Punishment.” Numbers “1” and “7” indicate a very strong feeling. Numbers “2” and “6” indicate a strong feeling. Numbers “3” and “5” indicate a fairly week feeling. Number “4” indicates you are undecided or do not understand the adjective pairs themselves. There are no right or wrong answer. Only circle one number per line.

• 1) Good 1 2 3 4 5 6 7 Bad
• 2) Wrong 1 2 3 4 5 6 7 Right
• 3) Harmful 1 2 3 4 5 6 7 Beneficial
• 4) Fair 1 2 3 4 5 6 7 Unfair
• 5) Wise 1 2 3 4 5 6 7 Foolish
• 6) Negative 1 2 3 4 5 6 7 Positive

Scoring:

Reverse code: 1, 3, & 4