Effects of social exclusion, observational learning, and oxytocin on fear learning and generalization: Evidence from behavioral and brain activity studies

Abstract

In fear learning, a neutral stimulus is associated to a threat. In fear generalization, fear responses are transferred to stimuli resembling threat stimuli. Here, I investigate how social exclusion, observational fear learning, and oxytocin—a hormone produced in social bonding—affect fear learning and generalization. An associative learning paradigm in which participants were learning associations between conditioned stimuli (i.e., geometric figures or pictures of faces) and unconditioned stimuli (i.e., electric shock) was applied together with a fear generalization procedure. Study I explored whether social exclusion, which was experimentally induced before fear learning, influences fear learning and generalization. Behavioral responses showed that social exclusion reduced fear learning and increased generalization. Brain functional near-infrared spectroscopy measurements indicated that the medial prefrontal cortex mediated the relationship between social exclusion and fear learning. Study II examined whether observational fear learning affects fear generalization differently than direct learning. The behavioral findings indicated that compared to direct learning, observational learning reduced fear learning and increased fear responses to generalization stimuli resembling the safety stimulus without having ever been paired to electric shock. Brain event-related potential results indicated that fear discrimination (reflected by the P1 component) and motivated attention (reflected by the late positive potential component) to generalization stimuli were reduced when learning occurred by observing another person compared to situations where participants learned by themselves. Study III investigated how oxytocin administrated after fear learning affects the fear responses to the generalization stimuli. The results showed that oxytocin compared to placebo attenuated generalization. Overall, social exclusion and observational learning increased fear generalization, while oxytocin had the opposite effect. These results are relevant in understanding social and hormonal factors underlying excessive fear generalization and they can be utilized in future studies aiming to overcome problems related to overgeneralized fear. Keywords: Fear generalization, social exclusion, oxytocin, observational fear learning