In light of Lang’s differentiation of the aversive and the approach system – and assumptions stemming from attachment theory – this study investigates the role of the approach or caregiving system for processing infant emotional stimuli by comparing IAPS pictures, infant pictures, and videos. IAPS pictures, infant pictures, and infant videos of positive, neutral, or negative content were presented to 69 mothers, accompanied by randomized startle probes. The assessment of emotional responses included subjective ratings of valence and arousal, corrugator activity, the startle amplitude, and electrodermal activity. In line with Lang’s original conception, the typical startle response pattern was found for IAPS pictures, whereas no startle modulation was observed for infant pictures. Moreover, the startle amplitudes during negative video scenes depicting crying infants were reduced. The results are discussed with respect to several theoretical and methodological considerations, including Lang’s theory, emotion regulation, opponent process theory, and the parental caregiving system.