Generalization of fear is one of the root causes of the exponential increase in anxiety and stress-related disorder. It becomes more trivial when healthy individuals generalize threats towards a non-threatening stimulus. It has been reported that several intrinsic factors modulate and alter fear generalization, to name a few reinforcements level, internal state, genetic background, sex difference etc. Though we clearly understand the neural mechanism of the generalized threat. However, the effect of reinforcement is an implicit factor and has been less examined. Hence, the study's rationale is that the reinforcement level is a decisive factor in conceptual fear generalization. A category-based differential fear conditioning paradigm was implemented using the four reinforcement levels, i.e., 100%, 62.5%, 37.5% and 0%. The conditioned responses for the fear acquisition phase were determined by calculating the mean expectancy ratings from trial 2 to trial 8. The conditioned responses for the generalization phase were obtained through the average scores of the expectancy ratings from trial 1 to trial 10. Our findings revealed the role of reinforcement on conditioned fear generalized to conceptually similar stimuli. In detail, the partial reinforcement category showed a wide generalization gradient, whereas the continuous reinforcement category showed a smooth generalization gradient across the trials. The findings of the study highlight that individuals tend to overgeneralize fear when the threat is unpredictable. It may have clinical implications as it demonstrates the role of the uncertainty of the aversive event in conceptual fear generalization.