Auditory Overshadowing in Preschoolers: A Preference for the Input, the System, or Both?

Auditory Overshadowing in Preschoolers: A Preference for the Input, the System, or Both? Allison O’Leary (oleary.83@osu.edu) Department of Psychology, 1835 Neil Avenue Columbus, OH 43210, USA Vladimir M. Sloutsky (sloutsky.1@osu.edu) Department of Psychology, 1835 Neil Avenue Columbus, OH 43210, USA Abstract Auditory overshadowing occurs when the presence of an auditory stimulus interferes with visual processing. The current study tested whether this occurs due to a privileged attentional status of auditory input or due to the dynamic characteristics of auditory input. To address these questions, preschoolers completed one of four discrimination tasks. In the sound, motion, and item baseline conditions, children discriminated these single information types by judging whether paired stimuli were the same or different. In the combined condition, children discriminated changing sounds, motions, or items in the face of competing input in the other two dimensions. Although children’s discrimination of all information types attenuated in the combined condition relative to baseline, motion and item discrimination attenuated more than auditory discrimination. This provides evidence that early in development auditory information receives privileged processing in the face of competing input. Keywords: Attention; Cross-modal processing; Cognitive development; Preschoolers Introduction To successfully navigate and form an understanding of our environment, we must develop the ability to efficiently integrate information from multiple sensory modalities. There is evidence that some multisensory integration occurs even in neonates, as demonstrated by the structural convergence of input from different sensory modalities (Stein & Meredith, 1993). However, it is clear that the ability to integrate multimodal information is not fully mature at birth and, in fact, exhibits a protracted developmental trajectory. For example, in contrast to normally functioning adults, infants and young children exhibit a phenomenon known as auditory overshadowing (Robinson & Sloutsky, 2004b). This occurs when the presence of an auditory stimulus interferes with one’s processing of a visual stimulus. That is, infants and young children more easily discriminate visual stimuli when presented in isolation than when paired with labels or sounds. In some cases, children completely fail to discriminate changes in a visual stimulus when presented simultaneously with a sound (Napolitano & Sloutsky, 2004). Importantly, although visual discrimination is impaired in the presence of auditory information, auditory discrimination does not suffer in the presence of visual information (Sloutsky & Napolitano, 2003; Robinson & Sloutsky, 2010b). The importance of audio-visual integration is especially apparent for processes like word learning, where individuals must map verbal labels to objects in visual space. If visual processing is inhibited when an auditory stimulus is present, auditory overshadowing could be a major contributor to the difficulty children face mapping words to objects. Indeed, 10-month-olds encoded only auditory information when presented with visual information and a verbally presented label. However, 16-month-olds demonstrated able processing of both the visual information and the label (as indicated by looking time preferences; Robinson & Sloutsky, 2004a). Although the ability to process auditory and visual information progresses through infanthood, even preschool- aged children show difficulties discriminating static visual stimuli in the presence of sounds and labels. Napolitano and Sloutsky (2004) demonstrated that 4-year-olds were susceptible to auditory overshadowing when asked to discriminate changes in the visual and auditory aspects of a target stimulus. Specifically, this effect was most profound when the visual and auditory stimuli were unfamiliar. Further, the authors demonstrated that this overshadowing was resistant to explicit instruction, in that it still occurred when children were asked to attend exclusively to visual information. More recent research has aimed to detail the conditions in which auditory overshadowing occurs and to elucidate the basic cognitive mechanisms underlying these effects. Input from the visual and auditory modalities seem to “compete” for processing resources early in development, whereas adults are able to process multimodal information (Robinson & Sloutsky, 2004a). Robinson and Sloutsky (2007a) also argued that overshadowing may occur during initial processing/encoding as well as during response selection. In addition, unfamiliar auditory stimuli slow visual processing, whereas familiar auditory stimuli do not (Robinson & Sloutsky, 2007b). Despite our understanding of the subtleties of the effect, major questions remain regarding the privileged status of auditory input and a number of hypotheses explaining auditory overshadowing effects have been proposed.