Pavlovian aversive conditioning is an evolutionarily well-conserved adaptation enabling organisms to learn to associate environmental stimuli with biologically aversive events. However, mechanisms underlying preferential (or enhanced) Pavlovian aversive conditioning remain unclear. Previous research has suggested that only specific stimuli that have threatened survival across evolution (e.g., snakes and angry faces) are preferentially conditioned to threat. Here, we challenge this view by showing that positive stimuli with biological relevance (baby faces and erotic stimuli) are likewise readily associated with an aversive event (electric stimulation) during Pavlovian aversive conditioning, thereby reflecting a learning bias to these stimuli. Across three experiments, our results reveal an enhanced persistence of the conditioned response to both threat-relevant and positive relevant stimuli compared with the conditioned response to neutral stimuli. These findings support the existence of a general mechanism underlying preferential Pavlovian aversive conditioning that is shared across negative and positive stimuli with high relevance to the organism and provide new insights into the basic mechanisms underlying emotional learning in humans.