ATTENTION OR MEMORY? EFFECTS OF FAMILIARITY AND NOVELTY ON THE Nc COMPONENT OF EVENT-RELATED BRAIN POTENTIALS IN SIX-MONTH-OLD INFANTS

Abstract

This study tested predictions from attentional, expectancy, and memory accounts of the Nc and early NSW components of ERPs in six-month-old infants. Visual stimuli were presented at the extremes of the probability continuum (a repeating stimulus versus novel stimuli) and at intermediate levels of probability (.80/.20 oddball task). Probability effects were found for Nc, early NSW, and visual fixation performance but there were no differences in the ERPs or behavior to familiar or novel stimuli. The results are discussed in terms of attentional and memory based interpretations of the Nc component.

Event-Related Brain Potentials and Visual Attention in Six-Month-Old Infants

“…The interpretation was that after experience with both frequent and oddball stimuli, the infants developed expectancy, with varying degrees of certainty, about which stimulus will appear next and that larger Nc amplitudes reflect disconfirmations of this expectancy and small Nc amplitude reflect confirmations. Ackles and Cook (2007), however, were not able to replicate these effects.…”

“…A second, lower probability stimulus (oddball) is presumed to be less familiar than the more frequently presented stimulus. Nc has been found to be sensitive to event probabilities in that larger amplitude Nc responses have been found to lower probability oddball than to more frequent stimuli (Ackles & Cook, 1998, 2007Courchesne et al, 1981;Hill Karrer, Karrer, Bloom, Chaney, & Davis, 1998;Karrer & Ackles, 1987, 1988Karrer, Wojtascek, & Davis, 1995). The early NSW component has also been found to be larger to oddball than frequent visual stimuli in some (Ackles & Cook, 2007;Karrer et al, 1995;Hill Karrer et al, 1998) but not all studies (Ackles & Cook, 1998).…”

“…However, the functional significance of the early NSW and the Nc components remains less clear and different views have been advanced concerning the specific cognitive processes underlying these components (for reviews and discussions see Ackles & Cook, 1998;Courchene, 1990;Friedman, 1991;Karrer, 1998;Karrer & Ackles, 1988;Nelson, 1994, Nelson & Monk, 2001. The principal goal of this study was to replicate and extend a previous study of six-month olds (Ackles & Cook, 2007) and test predictions from memory, expectancy, and attentional accounts of the Nc component. The results show that Nc is likely to reflect the allocation of attentional resources.…”

“…In a previous study, we tested predictions from attentional, expectancy, and memory accounts of Nc (Ackles & Cook, 2007). We reasoned that if the amount of experience with a stimulus is related to the strength of a memory for that stimulus, then more experience with a stimulus may lead to stronger memories and less experience may result in weaker memories (Rose, Feldman, & Jankowski, 2004).…”

“…The oddball effect on Nc in Ackles and Cook (2007) also do not lend support for the idea that Nc reflects a nonspecific attentional response or basic orienting response that is not sensitive to stimulus probabilities (Nelson, 1994;Nelson & de Haan, 1996;Nelson & deRegnier, 1992;Reynolds & Richards, 2005;Richards, 2003). Instead, Ackles and Cook (2007) (see also Ackles & Cook, 1998) argued that because Nc amplitude does not appear to be modulated primarily by stimulus characteristics, the amount of experience with a stimulus, mismatch operations, or always affected by stimulus probability, it is unlikely that it is an automatic, bottom-up, or completely stimulus-driven process.…”