Developmental changes in the discrimination of dynamic human actions in infancy

Abstract

Recent evidence suggests adults selectively attend to features of action, such as how a hand contacts an object, and less to configural properties of action, such as spatial trajectory, when observing human actions. The current research investigated whether this bias develops in infancy. We utilized a habituation paradigm to assess 4-month-old and 10-month-old infants’ discrimination of action based on featural, configural, and temporal sources of action information. Younger infants were able to discriminate changes to all three sources of information, but older infants were only able to reliably discriminate changes to featural information. These results highlight a previously unknown aspect of early action processing, and suggest that action perception may undergo a developmental process akin to perceptual narrowing.

Plasticity after perceptual narrowing for voice perception: reinstating the ability to discriminate monkeys by their voices at 12 months of age

“…An advantage for processing differences in native compared to foreign stimuli by 12 months of age has been documented across a number of domains, including faces (e.g., Pascalis et al, 2002; Lewkowicz and Ghazanfar, 2006; Kelly et al, 2007; Pons et al, 2009; Simpson et al, 2010), voices (Friendly et al, 2013), music (e.g., Lynch et al, 1990; Hannon and Trehub, 2005a, b; Trainor, 2005; Trehub and Hannon, 2006; Hannon and Trainor, 2007), language (e.g., Werker and Tees, 1984; Kuhl et al, 1992, 2006; Polka and Werker, 1994; Tsao et al, 2000; Kuhl, 2004, 2008; Palmer et al, 2012; for reviews see Werker and Tees, 2005; Curtin and Werker, 2007), and even action (Loucks and Sommerville, 2012). For example, 6-month-olds are equally good at discriminating two monkey faces as they are at discriminating two human faces, but 9-month-olds and adults are much better with human faces (Pascalis et al, 2002).…”

Attending to what matters: Flexibility in adults’ and infants’ action perception

“…For example, adult and infant observers selectively attend to how an actor's hand contacts objects: even when the goal of the action remains unchanged, both adults and 10-month-old infants find changes to hand contact information more salient than changes to spatial trajectory or temporal information in action (Loucks & Baldwin, 2009; Loucks & Sommerville, 2012a). For adults, this is true even when changes to spatial information are objectively larger than changes to hand contact information (Loucks & Baldwin, 2009; Loucks, 2011).…”

“…For adults, this is true even when changes to spatial information are objectively larger than changes to hand contact information (Loucks & Baldwin, 2009; Loucks, 2011). This aspect of selectivity also undergoes development during infancy: 4-month-old infants attend equally to hand contact, spatial trajectory, and temporal information in action, while 10-month-old infants have narrowed their attention and selectively focus on hand contact information (Loucks & Sommerville, 2012a). This focus on hand contact may aid in processing upcoming actions, as the type of hand contact used on an object has functional consequences: it constrains the possible future actions one can take with that object.…”

“…We tested infants and adults in the current work for two reasons. First, existing work suggests that there are developmental changes both in infants’ selective attention to various dimensions of action over the first year of life (Loucks & Sommerville, 2012a; Sommerville et al, 2005; Sommerville & Woodward, 2005), and in their ability to predict the goal of particular actions (Cannon, Woodward, Gredebäck, von Hofsten, & Turek, 2012; Kanakogi & Itakura, 2011), which are tied to their ability to produce particular goal-directed actions. Thus, we tested 9.5-month-old infants who have just begun to attain competence at aiming to drop and throw objects (Ruff, 1984) in order to investigate the earliest emergence of flexibility in infants’ attention to dimensions of human action given the context.…”

“…Second, comparing adults and infants allowed us to examine continuity in the flexible nature of action perception across the lifespan. Although by 10 months of age infants are similarly biased as adults to selectively attend to hand contact information (Loucks & Somerville, 2012a), there may be differences in flexibility between adults and infants as a result of infants’ more limited experience with action generally. In addition, for both age groups, no previous research has examined selective attention to properties of action for aimed dropping actions 1 .…”