¹Asan Medical Center, Department of Psychiatry, Seoul, Korea, Republic of, ²University of Ulsan College of Medicine, Department of Psychiatry, Seoul, Korea, Republic of

Background: Human preferences generally follow transitive logic, yet healthy individuals frequently demonstrate intransitivity (A > B > C > A), a phenomenon challenging traditional Rational Choice Theory. While often viewed as irrational, these deviations may reflect adaptive cognitive flexibility. Conversely, depression is frequently associated with cognitive rigidity and an inability to adapt to complex environmental demands.

Aims & Objectives: This study aimed to quantify preference intransitivity using a novel metric termed "tricksters" and to investigate whether patients with Major Depressive Disorder (MDD) exhibit altered patterns of transitivity compared to healthy controls. We hypothesized that the cognitive rigidity observed in depression would manifest as increased transitivity (fewer tricksters) in preference choices.

Method: We utilized a two-alternative forced-choice paradigm across six visual domains (including objects, colors, and graphic faces). The study recruited 21 patients with MDD and 21 age- and sex-matched healthy controls. We introduced the concept of "tricksters"—defined as the minimal set of alternatives preventing a linear order—to quantify the degree of intransitivity. The validity of this metric was assessed by analyzing response latencies during choices involving intransitive loops versus transitive descendants.

Results: Comparisons validated that choices involving tricksters were more cognitively demanding than transitive choices. Significantly, patients with MDD exhibited fewer tricksters (1.24 ± 0.77) compared to healthy subjects (2.29 ± 0.96), particularly in choices involving graphic facial stimuli (p<0.001). This reduction in tricksters indicates a higher degree of linear transitivity in the depressed group compared to controls.

Discussion & Conclusions: The findings suggest that MDD is characterized by heightened transitivity, aligning with previous reports linking lower cognitive stress to higher intransitivity. While healthy cognition maintains a level of intransitivity necessary for flexibility, the "hyper-transitive" structure in depression suggests a pathological rigidity. We propose that an appropriate level of intransitivity is adaptive, and its loss may serve as a cognitive marker for depression.