Recognition,discrimination and categorization of smiling by 5-month-old infants

Perceiving emotions correctly is foundational to the development of interpersonal skills. Five-month-old infants’ abilities to recognize, discriminate and categorize facial expressions of smiling were tested in three coordinated experiments. Infants were habituated to four degrees of smiling modeled by the same or different people; following habituation, infants were presented with a new degree of smile worn by the same and by a new person (Experiment 1), a new degree of smile and a fearful expression worn by the same person (Experiment 2) or a new degree of smile and a fearful expression worn by new people (Experiment 3). Infants showed significant novelty preferences for the new person smiling and for the fearful expressions over the new degree of smiling. These findings indicate that infants at 5 months can categorize the facial expression of smiling in static faces, and yet recognize the same person despite changes in facial expression; this is the youngest age at which these abilities have been demonstrated. The findings are discussed in light of the significance of emotion expression face processing in social interaction and infants’ categorization of faces.     

Infant perceptual and conceptual categorization: the roles of static and dynamic stimulus attributes

Infants' categorization of animals and vehicles based on static vs. dynamic attributes of stimuli was investigated in five experiments (N=158) using a categorization habituation-of-looking paradigm. In Experiment 1, 6-month-olds categorized static color images of animals and vehicles, and in Experiment 2, 6-month-olds categorized dynamic point-light displays showing only motions of the same animals and vehicles. In Experiments 3, 4, and 5, 6- and 9-month-olds were tested in an habituation-transfer paradigm: half of the infants at each age were habituated to static images and tested with dynamic point-light displays, and the other half were habituated to dynamic point-light displays and tested with static images. Six-month-olds did not transfer. Only 9-month-olds who were habituated to dynamic displays showed evidence of category transfer to static images. Together the findings show that 6-month-olds categorize animals and vehicles based on static and dynamic information, and 9-month-olds can transfer dynamic category information to static images. Transfer, static vs. dynamic information, and age effects in infant categorization are discussed.     

Perception of object-context relations: eye-movement analyses in infants and adults

Twenty-eight 4-month-olds' and twenty-two 20-year-olds' attention to object-context relations was investigated using a common eye-movement paradigm. Infants and adults scanned both objects and contexts. Infants showed equivalent preferences for animals and vehicles and for congruent and incongruent object-context relations overall, more fixations of objects in congruent object-context relations, more fixations of contexts in incongruent object-context relations, more fixations of objects than contexts in vehicle scenes, and more fixation shifts in incongruent than congruent vehicle scenes. Adults showed more fixations of congruent than incongruent scenes, vehicles than animals, and objects than contexts; equal fixations of animals and their contexts but more fixations of vehicles than their contexts; and more shifts of fixation when inspecting animals in context than vehicles in context. These findings for location, number, and order of eye movements indicate that object-context relations play a dynamic role in the development and allocation of attention.     

Assessing categorization performance at the individual level: a comparison of Monte Carlo simulation and probability estimate model procedures

Two analytical procedures for identifying young children as categorizers, the Monte Carlo Simulation and the Probability Estimate Model, were compared. Using a sequential touching method, children aged 12, 18, 24, and 30 months were given seven object sets representing different levels of categorical classification. From their touching performance, the probability that children were categorizing was then determined independently using Monte Carlo Simulation and the Probability Estimate Model. The two analytical procedures resulted in different percentages of children being classified as categorizers. Results using the Monte Carlo Simulation were more consistent with group-level analyses than results using the Probability Estimate Model. These findings recommend using the Monte Carlo Simulation for determining individual categorizer classification.     

Perception of three-dimensional shape specified by optic flow by 8-week-old infants

Sensitivity of 8-week-old infants to optical flow specifying the shape of a three-dimensional object was assessed. Infants viewed kinetic random-dot displays that specified three-dimensional cubes. The cubes were identical except for the presence or absence of an interior corner. Half of the infants viewed the full display. The other half viewed the central region of the displays, where the flow specifying the presence or absence of the corner differed. Infants in the full-view condition looked significantly longer to a novel cube than to the familiar cube following habituation. In contrast, infants in the partial-view condition looked equally to the novel and familiar cubes, ruling out the possibility that infants who viewed the full displays merely discriminated differences in motion in the central region of the two displays. These findings suggest that infants as young as 8 weeks perceive three-dimensional object shape from optic flow.     

Children’s Memory for Temporal Information: The Roles of Temporal Language and Executive Function

Abstract

The ability to recall the temporal order of events develops much more slowly than the ability to recall facts about events. To explore what processes facilitate memory for temporal information, we tested 3- to 6-year-old children (N?=?40) for immediate memory of the temporal order of events from a storybook, using a visual timeline task and a yes/no recognition task. In addition, children completed tasks assessing their understanding of before and after and the executive functions of inhibition using the Day/Night Stroop task and cognitive shifting using the Dimensional Change Card Sort (DCCS) task. Older children (Mage?=?69.25?months) outperformed younger children (Mage?=?52.35?months) on all measures; however, the only significant predictor of memory for the temporal ordering of events was cognitive shifting. The findings suggest that the difficulty in memory for temporal information is related to development of a general cognitive ability, as indexed by the DCCS, rather than specific temporal abilities.