Understanding Phenotypic Trait Differences and their Impact on Habitual Behaviour: A Fully Translational Approach

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Phenotypic trait differences lead to differences in psychological processing, ultimately producing differences in behaviour. One example is the ability of reward-associated conditioned stimuli (CSs) to command attention and support the attribution of incentive value (supporting 'sign-tracking') or to control behaviour, as in CS-response habits. We previously observed in rats an association between sign-tracking and dysfunctional behaviour on the Observing Response Task (ORT), a fully translational, rodent-to-human task assessing functional and dysfunctional checking. Similar associations have been observed between sign-tracking and compulsive-like drug-seeking behaviour in rodents, leading us to hypothesise that sign-tracking correlates with habitual, compulsive behaviour, whether expressed through drug-seeking or dysfunctional checking. Furthermore, these rodent data parallel findings in humans, that behaviours analogous to sign-tracking correlate with self-reported compulsive behaviour. We hypothesise that phenotypic trait differences in the attribution of incentive value predict, and may promote, habit formation and compulsive-like behaviour across species, and across the continuum from adaptive to maladaptive habits.


The reliance of previous work on self-report measures limits comparability between the human and rodent data. If we are to test whether the same mechanisms relate sign-tracking, habit formation and compulsivity in humans and animals, we need to test empirically whether sign-tracking in humans is associated with objective behavioural measurements, such as the human ORT. Furthermore, we need to know whether repetitive behaviours measured by the ORT are maladaptive and compulsive, and if sign-tracking leads to habit formation and compulsivity. We will use a cross-species approach to address these questions, providing a springboard for future neural interrogation of brain circuits while consolidating the translational relevance of our approach.