The Theory of General Acuity: A Psychophysical Application to Noncognitive Measurement Free From Introspective Self-Report J. Peter Leeds University of Baltimore The measurement of non-cognitive constructs (e.g., openness, honesty, and self- esteem) using introspective self-report has often been criticized for its vulnerability to validity-reducing response distortion. In this article, we present a theory of general acuity as an extension of Leeds’s (2012, 2018) theory of cognitive acuity. General acuity theory proposes that the higher a person’s standing on any mentally held construct, the more sensitive the person will be to distinctions in phenomena associated with that construct. If true, then it may be possible to measure standing on any construct by observing the person’s sensitivity to distinctions in many paired instances of the phenomena. We thus define general acuity as sensitivity to distinctions in construct-relevant (CR) phenomena as evidence of one’s standing on that construct and point out that the response demand being made is based on signal detection and not introspective self report. We report three studies of the (a) customer service orientation of Spanish sales personnel, (b) agreeableness of U.S. college students, and (c) conscientiousness of U.S. public service coordinators. In each study, we used paired CR statements and adjectives to present respondents with a series of CR signal contrasts to detect. We used psychophysical methods to estimate respondents’ construct signal sensitivity (i.e., acuity) and to assess test attentiveness and show that CR acuity is related to independent measures of the target constructs. We present the psychophysical framework, measurement proce- dures, and criterion/construct-related validity evidence for a general acuity theory, making the case for a common psychometric theory underpinning all cognitive and non-cognitive measurement. Keywords: general acuity, cognitive acuity, psychophysics, personality In 2012, Leeds proposed a theory of cogni- tive acuity and presented data showing how sensitivity to distinctions in the effectiveness of situational judgment test (SJT) response options (i.e., cognitive acuity) was correlated with in- dependent estimates of situation resolution abil- ity. Implicit in this theory is the proposition that possessing the situational judgment characteris- tic makes one sensitive to variation in response option resolution effectiveness. Leeds (2012) treated SJT item response options as construct- relevant (CR) signals differentially detectable X J. Peter Leeds, College of Arts and Sciences, Divi- sion of Applied Behavioral Sciences, University of Balti- more. I want to thank Vicente Feltrer from El Corte Inglés for his support in collecting the data in Study 1 and for operationalizing the first general acuity measure for com- mercial use; Thomas Mitchell from the University of Bal- timore for sponsoring the capture of data for Studies 2 and 3 and for being an insightful sounding board in theory development; Filip Lievens from the Department of Per- sonnel Management and Work and Organizational Psy- chology, Ghent University for his early discussions on the theoretical framework; Scott Burtnick from the U.S. Cus- toms and Border Protection and Oksana Naumenko from the University of North Carolina, Greensboro Department of Educational Research Methodology, for their work on applying item response theory to the data in Study 1; and finally John Ford of the University of Maryland Global Campus, for his assistance with latent semantic analysis in Studies 2 and 3. Correspondence concerning this article should be ad- dressed to J. Peter Leeds, who is now at 11554 Ivy Bush Court, Reston, VA 20191. E-mail: iamjleeds@gmail.com This document is copyrighted by the American Psychological Association or one of its allied publishers. This article is intended solely for the personal use of the individual user and is not to be disseminated broadly. Journal of Neuroscience, Psychology, and Economics © 2020 American Psychological Association 2020, Vol. 2, No. 999, 000 ISSN: 1937-321X http://dx.doi.org/10.1037/npe0000116 1