Examining infants' visual paired comparison performance in the US and rural Malawi

Abstract

Measures of attention and memory were evaluated in 6- to 9-month-old infants from two diverse contexts. One sample consisted of African infants residing in rural Malawi (N = 228, 118 girls, 110 boys). The other sample consisted of racially diverse infants residing in suburban California (N = 48, 24 girls, 24 boys). Infants were tested in an eye-tracking version of the visual paired comparison procedure and were shown racially familiar faces. The eye tracking data were parsed into individual looks, revealing that both groups of infants showed significant memory performance. However, how a look was operationally defined impacted some-but not other-measures of infant VPC performance. RESEARCH HIGHLIGHTS: In both the US and Malawi, 6- to 9-month-old infants showed evidence of memory for faces they had previously viewed during a familiarization period. Infant age was associated with peak look duration and memory performance in both contexts. Different operational definitions of a look yielded consistent findings for peak look duration and novelty preference scores-but not shift rate. Operationalization of look-defined measures is an important consideration for studies of infants in different cultural contexts.

Keywords: culture‐specific attention; eye tracking; infant cognition; visual recognition memory.

FIGURE 1

Distribution of ages for female infants (left) and male (right) in Malawi (top) and the US (bottom).

FIGURE 2

(a) Apparatus for infants in rural Malawi and (b) VPC stimulus set for infants in rural Malawi (top) and the US (bottom). Infants were seated on their parent’s lap (rural Malawi and US) or in a highchair (US) during the eye-tracking task and a curtain was used to block out visual distractions for both samples. All aspects of the apparatus and eye-tracking procedure were similar except that infants in the US were tested in a sound-attenuated room. Stimulus pairings were matched in terms of facial expression, perceived gender, and age for infants in rural Malawi and the US.

FIGURE 3

Schematic illustration of a single experimental trial for infants in rural Malawi (left) and the US (right) for the VPC procedure. Infants in both settings were presented with four individual trials that each consisted of an initial familiarization phase and two test arrays. An attention getter was displayed at the beginning of each trial and in-between stimulus arrays; an experimenter initiated a button press when infants’ fixation was detected toward the attention getter in the center of the screen.

FIGURE 4

Peak look duration by sample (blue = Malawi, red = US) as a function of operational definitions for a look (i.e., varying the minimum look duration and the maximum look away within a look). Scatter plots contain individual data points representing trial-level observations for infants in each sample and error bars indicate 95% confidence intervals for the estimated marginal means. The estimated marginal means for peak look duration in both samples (left), association between peak look duration and age in days (middle), and association between peak look duration and trial (right) are displayed as squares (sample) or regression lines (age and trial). Each row represents a different interruption duration threshold and each column represents a different look duration threshold.

FIGURE 5

Shift rate by sample (blue = Malawi, red = US) as a function of operational definition. Scatter plots contain individual data points representing trial-level observations for infants in each sample and error bars indicate 95% confidence intervals for the estimated marginal means. The estimated marginal means for shift rates in both samples (left), association between shift rates and age in days (middle), and association between shift rates and trial (right) are displayed for each look and interruption duration thresholds.

FIGURE 6

Novelty preference scores by sample (blue = Malawi, red = US) as a function of operational definition. Scatter plots contain individual data points representing trial-level observations for infants in each sample and error bars indicate 95% confidence intervals for the estimated marginal means. The estimated marginal means for novelty preference scores in both samples (left), association between novelty preference scores and age in days (middle), and association between novelty preference scores and trial (right) are displayed for each look and interruption duration threshold. The horizontal line bisecting the vertical axis represents chance (0.50) performance.

FIGURE 7

Interaction between information processing measures and sample on infants’ memory performance as a function of operational definition. The horizontal line bisecting the vertical axis represents chance (0.50) performance. Individual data points represent trial-level novelty preference scores for infants in the US (red) and Malawi (blue). The lines represent estimated marginal means and the shading around the lines represent 95% confidence intervals of the estimated marginal means.