New Reaction-Time Test Reveals Hidden Conflicts Behind Failed Health Goals

Almost everyone has been there: a firm resolution to exercise more, eat better, or sleep regularly, followed by the quiet erosion of that intention under the pressure of work deadlines, family obligations, and simple habit. Psychologists have long called this the intention–behavior gap, and decades of research suggest that the problem is not weak willpower alone but the architecture of a person’s goals themselves. When the goal of being physically active collides with the goal of advancing a career or spending time with friends, the health goal often loses. When goals align, they can instead pull each other forward. The trouble is that researchers have almost always measured these goal relationships by simply asking people to describe them, a method vulnerable to memory failures, social desirability, and limited self-insight. A new study published in Current Psychology by Catherine Culot of Ghent University and Université Libre de Bruxelles, together with Geert Crombez, Sara Kassas, Christophe Leys, Annique Smeding, and Ann DeSmet, introduces a way to measure these hidden dynamics without asking.

The new instrument, called the PEP-Goal, is the first implicit, reaction-time based measure of health goal conflict and facilitation. It is built on the Propositional Evaluation Paradigm, or PEP, a technique developed to assess personal beliefs and attitudes indirectly. In the PEP, participants are presented with statements and must judge whether each proposition is true or false, and the speed of those judgments carries the diagnostic weight. The logic is straightforward but powerful: if a proposition is easy for a person to endorse or reject because it fits their existing mental representation of the world, responses will be fast. If the proposition clashes with that representation, responses slow down. Unlike classical implicit measures such as the Implicit Association Test, which rely on associative strength between concepts, the PEP targets propositional beliefs, the structured, truth-evaluable contents of thought. This matters for goals, because whether someone believes that their career ambitions undermine their exercise routine is a proposition, not a mere association.

The theoretical backdrop for the study is goal systems theory, which treats goals not as isolated desires but as a network of interconnected pursuits. Within this framework, researchers distinguish between horizontal relations, the links between a health goal and other life goals such as work, relationships, or leisure, and vertical relations, the links between a health goal and a person’s deeper personal values, such as security, achievement, or hedonism. Both kinds of relations can facilitate or impede health behavior. A person whose value system emphasizes self-discipline may find healthy eating naturally supported from above, while someone whose leisure goals revolve around social drinking may find the same goal undermined from the side. Previous work, including studies using accelerometer-assessed physical activity, has shown that these intergoal dynamics predict real-world behavior, but the evidence has rested almost entirely on explicit questionnaires, most notably Personal Project Analysis, a method pioneered by Brian Little in which participants list and rate their ongoing personal projects.

Culot and colleagues set out to validate the PEP-Goal against this established self-report standard and, crucially, against objective behavior. Participants completed the implicit paradigm, which presented them with propositions concerning the relations between their health goals and other goals or values, and their response times were converted into implicit conflict and facilitation scores. They also completed an adapted version of Personal Project Analysis designed to capture the same horizontal and vertical relations explicitly. The researchers then tracked participants’ actual physical activity over one week using wearable activity trackers, providing an objective behavioral outcome that does not depend on the honesty or accuracy of self-description. The study was funded by the Fonds de la Recherche Scientifique (FNRS) under grant number 40003190, approved by the ethics committee of the Faculty of Psychology at Université Libre de Bruxelles, and conducted in line with the Declaration of Helsinki. Data and code were made openly available through the Open Science Framework.

The results delivered a striking dissociation. The implicit PEP-Goal scores did not simply mirror what participants reported on the explicit questionnaire; the two measures diverged in notable ways, suggesting that they tap partly different psychological realities. This kind of divergence is exactly what one would expect if explicit reports are filtered through introspection and self-presentation while reaction-time measures capture more automatic evaluative processes. It also echoes a broader and sometimes sobering literature on implicit measures, which has shown that their ability to predict behavior varies widely depending on how well the measure matches the behavior in question. The Belgian team’s design directly addressed one of the most common criticisms of implicit measures by aligning the content of the paradigm precisely with the target: goal relations, rather than generic attitudes toward health.

The most consequential finding concerned prediction. Implicit horizontal PEP-Goal scores, those capturing the relations between health goals and other life goals, uniquely predicted objectively tracked physical activity over the following week, above and beyond what the explicit self-report measures could explain. In other words, the reaction-time paradigm detected something about the structure of participants’ goal networks that questionnaires missed, and that something translated into measurable movement. For a field in which self-reported physical activity is notoriously inflated and often weakly correlated with actual behavior, the demonstration that an implicit measure adds incremental predictive validity over an explicit one is a meaningful methodological advance. It suggests that some of the conflicts and synergies shaping health behavior operate below the level of ready verbal report.

The vertical relations told a different story. Implicit scores capturing the links between health goals and personal values showed no significant predictive value for physical activity. The authors are careful about this null result, and it fits with a nuanced view of how values operate. Personal values, as formalized in Schwartz’s theory of basic values, are relatively stable, abstract motivational commitments. Their influence on concrete daily behavior may be diffuse and mediated by many intermediate steps, making them harder to capture with a quick truth-evaluation task. Alternatively, the vertical propositions used in the paradigm may simply require further refinement before they can register these deeper alignments. Either way, the asymmetry between horizontal and vertical results is itself informative: it implies that the everyday friction between competing goals, rather than abstract value conflict, is where implicit measurement currently pays off.

The practical implications reach into the design of health interventions. Personalized health-behavior programs increasingly try to tailor advice to an individual’s life circumstances, and goal conflict is a natural target: if a program can identify that a patient’s exercise goal is being quietly sabotaged by a competing work goal, it can help restructure schedules, reframe priorities, or build implementation plans that protect the health behavior. A brief, computerized reaction-time task could, in principle, screen for these conflicts faster and more sensitively than lengthy project interviews, and could detect facilitative relations worth exploiting as well as conflicts worth defusing. The authors caution that the tool still needs refinement before it is ready for applied use, but they argue that the current findings offer promising initial evidence for both the predictive validity and the practical utility of the PEP-Goal in health-behavior research and intervention planning.

The study also contributes to a wider methodological conversation in psychology about what implicit measures are and what they can honestly claim to do. Following the normative analysis offered by Jan De Houwer and colleagues, implicit measures are best understood as indirect measures, inferring mental content from performance on a task, rather than as windows onto a separate unconscious mind. On this reading, the PEP-Goal’s success is not evidence of a hidden unconscious, but evidence that the propositional structure of people’s beliefs about their own goals leaves a measurable trace in the speed of their judgments. That trace, the study shows, carries information about future behavior that introspection does not fully supply. As wearable sensors make objective health behavior ever easier to track, pairing them with validated implicit measures of goal dynamics could close the loop between what people believe about their motivations and what their bodies actually do. The PEP-Goal is an early step in that direction, and its horizontal findings in particular suggest that the most important obstacles to healthy living may be the ones people cannot easily put into words.

Subject of Research: Validation of an implicit reaction-time measure of health goal conflict and facilitation for predicting physical activity

Article Title: The PEP-GOAL: validation of a propositional evaluation paradigm as an implicit measure of health goal conflict and facilitation

Article References: Culot, C., Crombez, G., Kassas, S., Leys, C., Smeding, A., & DeSmet, A. (2026). The PEP-GOAL: validation of a propositional evaluation paradigm as an implicit measure of health goal conflict and facilitation. Current Psychology, 45(18), Article 1504. https://doi.org/10.1007/s12144-026-10035-6

Image Credits: AI Generated

DOI: 10.1007/s12144-026-10035-6

Keywords: implicit measure, goal conflict, goal facilitation, health psychology, physical activity, propositional evaluation paradigm, psychometrics, personal values, intention-behavior gap, wearable activity trackers, goal systems theory, behavior change