Object correspondence in audition echoes vision: Not only spatiotemporal but also feature information influences auditory apparent motion

A crucial ability of our cognition is the perception of objects and their motions. We can perceive objects as moving by connecting them across space and time. This is possible even when the objects are not present continuously, as in the case of apparent motion displays like the Ternus display, consisting of two sets of stimuli, shifted to the left or right, separated by a variable inter-stimulus interval (ISI). This is an ambiguous display, which can be perceived as both stimuli moving uniformly to the right (group motion) or one stimulus moving across the stationary center stimulus (element motion), depending on which stimuli are connected over time. Which percept is seen can be influenced by the ISI and the stimulus features. Previous experiments have shown that the Ternus effect also exists in the auditory modality and that the auditory Ternus is also dependent on the ISI. This is a first indication that correspondence might work similarly in the visual and auditory modality. To test this idea further, we investigated whether the auditory Ternus effect is dependent on the stimulus features by creating a frequency-based bias using a high and a low sinewave tone as Ternus stimuli. This bias was compatible either with the element-motion or with the group-motion percept. Our results showed an influence of this feature bias in addition to an ISI effect, suggesting that the visual and the auditory modalities might both use the same mechanism to connect objects across space and time.