Occlusion Is Hard: Comparing Predictive Reaching for Visible and Hidden Objects in Infants and Adults

Infants can anticipate the future location of a moving object and execute a predictive reach to intercept the object. When a moving object is temporarily hidden by darkness or occlusion, 6‐month‐old infants’ reaching is perturbed, but performance on darkness trials is significantly better than occlusion trials. How does this reaching behavior change over development? Experiment 1 tested predictive reaching of 6‐ and 9‐month‐old infants. While there was an increase in the overall number of reaches with increasing age, there were significantly fewer predictive reaches during the occlusion compared to visible trials and no age‐related changes in this pattern. The decrease in performance found in Experiment 1 is likely to apply not only to the object representations formed by infants but also those formed by adults. In Experiment 2 we tested adults with a similar reaching task. Like infants, the adults were most accurate when the target was continuously visible and performance in darkness trials was significantly better than occlusion trials, providing evidence that there is something specific about occlusion that makes it more difficult than merely lack of visibility. Together, these findings suggest that infants’ and adults’ capacities to represent objects have similar signatures throughout development.     

Eighteen-month-old infants show false belief understanding in an active helping paradigm

Recently, several studies have claimed that soon after their first birthday infants understand others’ false beliefs. However, some have questioned these findings based on criticisms of the looking-time paradigms used. Here we report a new paradigm to test false belief understanding in infants using a more active behavioral response: helping. Specifically, the task was for infants to help an adult achieve his goal - but to determine that goal infants had to take into account what the adult believed (i.e., whether or not he falsely believed there was a toy inside a box). Results showed that by 18 months of age infants successfully took into account the adult’s belief in the process of attempting to determine his goal. Results for 16-month-olds were in the same direction but less clear. These results represent by far the youngest age of false belief understanding in a task with an active behavioral measure.     

Development of the other-race effect during infancy: Evidence toward universality?

The other-race effect in face processing develops within the first year of life in Caucasian infants. It is currently unknown whether the developmental trajectory observed in Caucasian infants can be extended to other cultures. This is an important issue to investigate because recent findings from cross-cultural psychology have suggested that individuals from Eastern and Western backgrounds tend to perceive the world in fundamentally different ways. To this end, the current study investigated 3-, 6-, and 9-month-old Chinese infants’ ability to discriminate faces within their own racial group and within two other racial groups (African and Caucasian). The 3-month-olds demonstrated recognition in all conditions, whereas the 6-month-olds recognized Chinese faces and displayed marginal recognition for Caucasian faces but did not recognize African faces. The 9-month-olds’ recognition was limited to Chinese faces. This pattern of development is consistent with the perceptual narrowing hypothesis that our perceptual systems are shaped by experience to be optimally sensitive to stimuli most commonly encountered in one’s unique cultural environment.     

The influence of electronic sound effects on learning from televised and live models

Infants rapidly accrue information via imitation from multiple sources, including television and electronic toys. In two experiments, we examined whether adding sound effects to video or live demonstrations would influence imitation by 6-, 12-, and 18-month-olds. In Experiment 1, we added matching and mismatching sound effects to target actions presented by a televised model. We found that 6-month-olds reproduced the target actions regardless of whether the sound effects were matched or mismatched, whereas 12- and 18-month-olds reproduced the actions only when the sound effects were matched. In Experiment 2, we added matching sound effects to target actions presented by a live model. The addition of sound effects disrupted imitation performance by 6-, 12-, and 18-month-olds. Overall, imitation provides a clear behavioral measure of rapid changes in learning from television and electronic toys during infancy. These findings have practical implications for producers and parents regarding learning in the digital age and theoretical implications regarding the development of integrated action-perception representational systems.     

Development of infants’ attention to faces during the first year

In simple tests of preference, infants as young as newborns prefer faces and face-like stimuli over distractors. Little is known, however, about the development of attention to faces in complex scenes. We recorded eye-movements of 3-, 6-, and 9-month-old infants and adults during free-viewing of clips from A Charlie Brown Christmas (an animated film). The tendency to look at faces increased with age. Using novel computational tools, we found that 3-month-olds were less consistent (across individuals) in where they looked than were older infants. Moreover, younger infants’ fixations were best predicted by low-level image salience, rather than the locations of faces. Between 3 and 9 months of age, infants gradually focused their attention on faces. We discuss several possible interpretations of this shift in terms of social development, cross-modal integration, and attentional/executive control.     

Going beyond the specifics: Generalization of single actions, but not temporal order, at 9 months

We examined generalization in 9-month-old infants after a 24-h delay using deferred imitation. Infants flexibly applied their knowledge of sequence actions across changes in props even though they had no opportunity for immediate imitation.     

Sensory information affords exploration of posture in newly walking infants and toddlers

The development of posture and locomotion provides a valuable window for understanding the ontogeny of perception-action relations. In this study, 13 infants were examined cross-sectionally while standing quietly either hands-free or while lightly touching a contact surface. Mean sway amplitude results indicate that infants use light touch for sway attenuation (≈28–40%) as has been seen previously with adults (Jeka & Lackner, 1994). Additionally, while using the contact surface, movement patterns of the head and trunk show reduced temporal coordination (≈25–40%), as well as increased temporal variability, as compared to no touch conditions. These findings are discussed with regard to the ontogeny of perception-action relations, with the overall conclusion that infants use somatosensory information in an exploratory manner to aid in the development of an accurate internal model of upright postural control.     

Spontaneous visual search during the first two years: Improvement with age but no evidence of efficient search

Efficient visual search, wherein reaction times to acquire targets are largely independent of array size, is commonly observed in adults. Evidence for efficient search in infants may imply that selective attention to visual features is similar across development. In the current cross-sectional eye-tracking study, we examined spontaneous visual search at 6, 12, 18, and 24 months. Infants were presented with Random arrays (one target among 7, 13, or 26 pseudorandomly distributed elements) and Circle arrays (one target among 4, 7, or 13 elements arranged in a circle). Contrary to predictions, we did not find evidence of efficient search among infants. With increasing array size, time-to-target increased, the proportion of targets fixated (analogous to accuracy) decreased, and the proportion of first looks to the target decreased for both types of array (ps < .001). For Random arrays, the proportion of first looks to the target was similar to chance for all ages and array sizes; for Circle arrays, it exceeded chance for some ages and array sizes. The proportion of targets fixated and first looks to target increased with age across display types (ps < .05). We also tested adults with the same stimuli under similar conditions; the adults showed evidence of efficient visual search. Possible explanations and implications are discussed.     

The importance of feature distribution and correlation for simulating 3 to 4-month-old infants' visual categorization processes

Mareschal, French, and Quinn (2000) and Mareschal, Quinn, and French (2002) have proposed a connectionist model of visual categorization in 3- to 4-month-old infants that simulates and predicts previously unexplained behavioural effects such as the asymmetric categorization effect (French, Mareschal, Mermillod, & Quinn, 2004). In the current paper, we show that the model's ability to simulate the asymmetry depends on the correlational structure of the stimuli. These results are important given that adults (Anderson & Fincham, 1996) as well as infants (Younger & Cohen, 1986) are able to rely on correlation information to perform visual categorization. At a behavioural level, the current paper suggests that pure bottom-up processes, based on the correlational structure of the categories, could explain the disappearance of the asymmetry in older 10-month-old infants (Furrer & Younger, 2005). Moreover, our results also raise new challenges for visual categorization models that attempt to simulate the shift from asymmetric categorization in 3- to 4-month-old to symmetric categorization in 10-month-old infants (Shultz & Cohen, 2004; Westermann & Mareschal, 2004, 2012).     

Internal feature saliency as a marker of familiarity and configural processing

Two experiments that explore the internal feature advantage (IFA) in familiar face processing are reported. The IFA involves more efficient processing of internal features for familiar faces over unfamiliar ones. Experiment 1 examined the possibility of a configural basis for this effect through use of a matching task for familiar and unfamiliar faces presented both upright and upside-down. Results revealed the predicted IFA for familiar faces when stimuli were upright, but this was removed when stimuli were inverted. Experiment 2 examined the degree of training required before the IFA was demonstrated. Latency results revealed that whilst 90–180 s of exposure was sufficient to generate an IFA of intermediate magnitude, 180–270 s of exposure was required before the IFA was equivalent to that demonstrated for a familiar face. Taken together, these results offer three conclusions: First, the IFA is reaffirmed as an objective indicator of familiarity; second, the IFA is seen to rest on configural processing; and finally, the development of the IFA with familiarity indicates a development of configural processing with familiarity. As such, insight is gained as to the type of processing changes that occur as familiarity is gradually acquired.