Neural Correlates of Individual Differences in Infant Visual Attention and Recognition Memory

Abstract

Past studies have identified individual differences in infant visual attention based upon peak look duration during initial exposure to a stimulus. Colombo and colleagues (e.g., Colombo & Mitchell, 1990) found that infants that demonstrate brief visual fixations (i.e., short lookers) during familiarization are more likely to demonstrate evidence of recognition memory during subsequent stimulus exposure than infants that demonstrate long visual fixations (i.e., long lookers). The current study utilized event-related potentials to examine possible neural mechanisms associated with individual differences in visual attention and recognition memory for 6-and 7.5-month-old infants. Short-and long-looking infants viewed images of familiar and novel objects during ERP testing. There was a stimulus type by looker type interaction at temporal and frontal electrodes on the late slow wave (LSW). Short lookers demonstrated a LSW that was significantly greater in amplitude in response to novel stimulus presentations. No significant differences in LSW amplitude were found based on stimulus type for long lookers. These results indicate deeper processing and recognition memory of the familiar stimulus for short lookers.

Infant visual attention and object recognition

“…Colombo and colleagues (Colombo, 1993; Colombo & Mitchell, 1990; Colombo, Mitchell, Coldren, & Freeseman, 1991; Colombo, Mitchell, & Horowitz, 1988) have shown that infants who demonstrate brief visual fixations (i.e., short lookers) during familiarization are more likely to demonstrate evidence of recognition memory during subsequent stimulus exposure than infants who demonstrate long visual fixations (i.e., long lookers). Reynolds, Guy, and Zhang (2011) reported that short-looking infants demonstrated significantly greater amplitude LSWs to novel compared to familiar stimuli indicative of recognition memory for the familiar object (see Figure 2). These memory effects occurred at both frontal and temporal electrodes for short lookers.…”

“…However, significant changes in the amplitude of the LSW are routinely observed across repeated stimulus presentations or with increased familiarity. Thus, the LSW is believed to be associated with stimulus encoding and infant recognition memory (de Haan & Nelson, 1999; Reynolds, Guy, & Zhang, 2011; Nelson & Collins, 1991; Nelson & Collins, 1992; Snyder, 2010; Snyder, Webb, & Nelson, 2002; Snyder et al, 2010; Webb, Long, & Nelson, 2005; Wiebe et al, 2006). From 4 to 12 months, infants become increasingly more likely to demonstrate LSW correlates of recognition of a fully processed stimulus in response to previously encountered stimuli (Nelson & Collins, 1992; Nelson & deRegnier, 1992; Reynolds & Richards, 2011).…”

“…Reynolds, Guy, and Zhang (2011) examined the impact of individual differences in infant visual attention on object recognition. Infants of 6 and 7.5 months of age were tested in a procedure in which they were familiarized with a single object, and then shown the familiar object on 50% of the ERP trials, and novel objects on the other 50% of trials.…”

“…In contrast, long-lookers process local elements prior to processing global properties. The global-precedence effect is characteristic of a mature and efficient visual processing strategy (Kimchi, 1992), and these differences in processing strategy would explain the long-lookers inability to fully process the more complex objects used as stimuli by Reynolds and colleagues (2011). Although these two sets of findings (Guy et al, 2013; Reynolds et al, 2011) indicate that an infant’s attentional style influences early recognition memory, because infants in these studies were familiarized with the repeated stimulus in a familiarization phase prior to the ERP testing the findings do not provide insight into exactly how attention influences stimulus encoding and subsequent recognition memory.…”

“…The influence of attention on stimulus encoding and recognition memory has been examined using heart rate as a psychophysiological index of infant attention during ERP tasks (Reynolds et al, 2005, 2010, 2011; Richards, 2003). Changes in HR throughout ERP testing were used to separate trials in which infants were deeply engaged in sustained attention (during looking paired with significant heart rate decelerations) from trials in which infants were inattentive and heart rate was at or above baseline levels (e.g., Casey & Richards, 1988; Richards, 1997; Richards & Casey, 1991; see review, Reynolds & Richards, 2008).…”