Effects of Anxiety on Spontaneous Ritualized Behavior

Environmental uncertainty and uncontrollability cause psycho-physiological distress to organisms [1-3], often impeding normal functioning [4, 5]. A common response involves ritualization, that is, the limitation of behavioral expressions to predictable stereotypic and repetitive motor patterns [6-8]. In humans, such behaviors are also symptomatic of psychopathologies like obsessive-compulsive disorder (OCD) [8, 9] and autism spectrum disorders (ASDs) [10, 11]. Although these reactions might be mediated by different neural pathways, they serve to regain a sense of control over an uncertain situation [12-15] by engaging in behavioral patterns characterized by redundancy (superfluous actions that exceed the functional requirements of a goal), repetitiveness (recurrent behaviors or utterances), and rigidity (emphasis on fidelity and invariance) [8, 9, 16, 17]. We examined whether ritualized behavior will manifest spontaneously as a dominant behavioral strategy in anxiogenic situation. Manipulating anxiety, we used motion-capture technology to quantify various characteristics of hand movements. We found that induced anxiety led to an increase in repetitiveness and rigidity, but not redundancy. However, examination of both psychological and physiological pathways revealed that repetitiveness and rigidity were predicted by an increase in heart rate, while self-perceived anxiety was a marginally significant predictor of redundancy. We suggest that these findings are in accordance with an entropy model of uncertainty [18], in which anxiety motivates organisms to return to familiar low-entropy states in order to regain a sense of control. Our results might inform a better understanding of ritual behavior and psychiatric disorders whose symptoms include over-ritualization.