Developmental and Real-time Influences on Infant Locomotor Activity: Effects of Locomotor Posture and Toy Dispersion

• In Event: Novel Findings and New Methods in Motor Skill Development, Perception, & Learning

Abstract

The onset of independent walking fundamentally changes infants’ interactions with the world. When infants transition from crawling to walking, they can cover more ground in less time (Adolph et al., 2012). Walking also provides access to a larger visual field (Kretch, Franchak, & Adolph, 2014). Crawlers primarily see the ground in front of their hands, whereas walkers’ higher vantage point allows them to see the whole room. But is a faster speed and higher vantage point always advantageous? Here, we tested the effects of locomotor posture in two environmental conditions and video-coded how much infants moved in each condition. Using a within-subjects design, we tested age-matched crawling and walking infants (M = 12.5 months; range = 11.5 – 14.1 months) during free play with their caregivers in two 10-minute conditions in which we varied the proximity of interesting destinations—toys clustered in one location versus dispersed around the room. Due to COVID-19, we report preliminary data from 11 crawling and 5 walking infants (planned ns = 20 per group).

We predicted that walkers would move more than crawlers overall, and that both crawlers and walkers would move more in the toys-dispersed condition compared to the toys-clustered condition. We also predicted an interaction between locomotor posture and toy condition, such that walkers would move most in the toys-dispersed condition. Our preliminary results largely support our predictions, although our full sample is needed for appropriate power. Averaged across conditions, walkers spent more time in motion (M = 29.2%) than crawlers (M = 11.0%), supporting a main effect of locomotor posture (t(14) = -4.64, p<.001; Figure 1A). With crawlers and walkers collapsed to one group, infants tended to spend more time in motion in the toys-dispersed condition (M = 19.2%) compared to the toys-clustered condition (M = 14.1%), albeit the difference was not significant (t(15) = -1.68, p = .114; Figure 1B). Most important, as predicted, we found preliminary evidence for an interaction between locomotor posture and condition: Walkers moved more in the toys-dispersed condition compared to the toys-clustered condition (M difference = 10.8%), whereas the mean difference for crawlers was only 2.5%; however, change scores were not significantly different between crawlers and walkers (t(14)= -1.30, p = .216; Figure 1C). The complete data set is needed to confirm our preliminary findings.

Assuming our predictions are supported by more data, why would walkers display an advantage over crawlers only in the toys-dispersed condition? The faster speed and higher vantage point for walkers might only be beneficial when the locations of interesting objects are spread throughout the room, as they were in the toys-dispersed condition. In the toys-clustered condition, walking provides no advantage. Our findings suggest an interplay between developmental and real-time factors, such that the interaction between locomotor posture and environmental conditions shapes infants’ locomotor activity.

Authors

• Christina Hospodar, New York University
  Presenting Author

• Justine Hoch, New York University
  Non-Presenting Author

• Yasmine Elasmar, New York University
  Non-Presenting Author

• Karen E Adolph, New York University
  Non-Presenting Author