Attribute capture underlying the precedence effect in rats

In a reverberant environment, humans with normal hearing can perceptually fuse the soundwave from a source with its reflections off nearby surfaces into a single auditory image, whose location appears to be around the source. This phenomenon is called the precedence effect, which is based on the perceptual capture of the reflected (lagging) sounds' attributes by the direct wave from the source. Using the paradigm of attentional modulation of the prepulse inhibition (PPI) of the startle reflex, with both the prepulse-feature specificity and the perceived-prepulse-location specificity, this study was to examine whether the perceptual attribute capture underlying the precedence effect occurs in rats. One broadband continuous noise was delivered by each of two spatially separated left and right loudspeakers with a 1-ms inter-loudspeaker delay. A silent gap was embedded in one of the two noises as the prepulse stimulus. The results showed that regardless of whether the gap was physically in the leading or lagging noise when the leading noise was either the left or right one, fear conditioning the gap enhanced PPI only when the leading noise was delivered from the loudspeaker that was the leading but not the lagging loudspeaker during the conditioning, indicating that due to the spatial specificity (either left or right) in the attentional enhancement of PPI, the perceived location of the conditioned gap was always on the leading side even though the gap was physically on the lagging side. Thus, rats have the same perceptual ability of attribute capture, thereby experiencing the auditory precedence effect as humans.