Table 1.

Definitions of Theory of Planned Behavior constructs, and examples of items used to measure each

Measure	Construct	Example
Direct	Attitude	Attitude toward performing the behavior: The police officer’s evaluation (unfavorable or favorable) of referring individuals with a suspected mental illness to mental health services (e.g., “I think that referring subjects who appear to have a mental illness to mental health services is: [useless – useful]”)
	Subjective norm	Belief regarding whether most people approve or disapprove of the behavior: The police officer’s perceived social pressure to refer individuals with a suspected mental illness to mental health services (e.g., “Most people who are important to me would approve of me referring a subject who appears to have a mental illness to mental health services” [extremely unlikely – extremely likely])
	Perceived behavioral control	Overall perception of the officer’s control over performing the behavior: The police officer’s perceived ease or difficulty of referring individuals with a suspected mental illness to mental health services (e.g., “I am confident that I can refer a subject who appears to have a mental illness to mental health services, if needed” [strongly disagree – strongly agree])
Indirect	Attitude	Attitude = Behavioral beliefs × Outcome evaluations Behavioral beliefs: Beliefs about the likelihood that referring individuals with a suspected mental illness to mental health services will result in certain outcomes (e.g., “Referring subjects who appear to have a mental illness to mental health services helps avoid incarceration of these individuals” [extremely unlikely – extremely likely]) Outcome evaluations: Good/bad value of the outcome (e.g., “Incarceration of subjects who appear to have a mental illness is: [undesirable – desirable]”)
	Subjective norm	Subjective norm = Normative beliefs × Motivation to comply Normative beliefs: Beliefs about referents’ approval or disapproval of referral to mental health services. The referents included supervisors, coworkers, family members, friends/ neighbors, mental health professionals, on-site partner, subjects with a mental illness, and the general public. (e.g., “My supervisor would approve of me referring a subject who appears to have a mental illness to mental health services” [extremely unlikely – extremely likely]) Motivation to comply: Motivation to do what each referent thinks (e.g., “When dealing with subjects who appear to have a mental illness, I usually do what my supervisor thinks I should do” [strongly disagree – strongly agree])
	Perceived behavioral control	Perceived behavioral control = Control beliefs × Perceived power Control beliefs: Beliefs about likelihood of occurrence of factors that may facilitate or impede mental health services referral (e.g., “Subjects who appear to have a mental illness may not recognize that they have a mental illness and/or substance use problem” [extremely unlikely – extremely likely]) Perceived power: Perceived effect about each of these factors in making mental health services referral difficult or easy (e.g., “When a subject who appears to have a mental illness does not recognize that he/she has a mental illness, this makes it [difficult – easy] for me to refer them to mental health services”)
Behavioral intention		The police officer’s perceived/reported likelihood of referring individuals with a suspected mental illness to mental health services (e.g. “When I encounter subjects who appear to have a mental illness, I take them to emergency receiving facilities” [extremely unlikely – extremely likely])