Developmental trajectories of picture-based object representations during the first year of life.

Experience with an object's photograph changes 9-month-olds' preference for the referent object, confirming they can represent objects from pictures. However, picture-based representations appear weaker than object-based representations. The current study's first objective was to investigate age differences in object recognition memory after familiarization with objects' pictures. The second objective was to test whether age differences in object permanence sensitivity with picture-based representations match those found with object-based representations, whereby 7-month-olds search more for familiar hidden objects but 11-month-olds search more for novel ones. Six- and 11-month-olds were familiarized with an object's photo and tested on their representation of the real object by comparing their reaching for it versus a novel object. Objects were visible under conditions testing recognition memory and hidden under conditions testing object permanence. Like 9-month-olds, 6- and 11-month-olds preferred novelty with visible objects, showing early object recognition after picture familiarization, as well as developmental continuity. Unlike 9-month-olds, who switched to preferring familiarity with hidden objects, 6- and 11-month-olds switched to null preference. This pattern fails to match 7- and 11-month-olds' hidden-object preferences after familiarization with real objects, revealing discontinuity in sensitivity to object permanence after picture familiarization, and suggesting that picture-based representations are weaker than object-based ones.

Can infants use video to update mental representations of absent objects?

Before their second birthday, infants can update their knowledge based on what someone tells them, but can they do so based on what a video shows them? The current study explored whether infants can update their representation of an absent object's properties after seeing a video of something happening to it, following seminal work showing that they can update their representation after being told about something happening to it (Ganea et al., 2007). It thus adapted an existing paradigm for testing infants' understanding of references to absent objects (using language) to investigate a different symbolic medium (video). Twenty-two-month-olds first played with a toy and later saw on video that the toy underwent a change in state while they were out of the room. Infants in the current study did not subsequently identify the toy based on this new information, whereas those in previous research did. Infants this age thus appear less likely to update their representation of an absent object's properties using video than using language. This result is consistent with the possibility that infants may understand the representational function of symbolic objects later in development than they understand the representational function of language. It also aligns with evidence of the video deficit in which infants learn less effectively from video than from firsthand experience.

Self or (M)other? Infants' Sensitivity to Bodily Overlap With Their Mother Reflects Their Dyadic Coordination.

Adults experience greater self-other bodily overlap in romantic than platonic relationships. One of the closest relationships is between mother and infant, yet little is known about their mutual bodily representations. This study measured infants' sensitivity to bodily overlap with their mother. Twenty-one 6- to 8-month-olds watched their mother's face or a stranger's face being stroked synchronously versus asynchronously with their own face. Infants preferred synchrony only when viewing their mother, not when viewing the stranger. Infants who strongly preferred synchrony with their mother also experienced less coordination with her in naturalistic interactions. Infants thus appear sensitive to bodily overlap with their mother, and this overlap reflects dyadic coordination, supporting theoretical accounts of intersubjectivity in the development of the bodily self.

Sound effects: Multimodal input helps infants find displaced objects.

Before 9 months, infants use sound to retrieve a stationary object hidden by darkness but not one hidden by occlusion, suggesting auditory input is more salient in the absence of visual input. This article addresses how audiovisual input affects 10-month-olds' search for displaced objects. In AB tasks, infants who previously retrieved an object at A subsequently fail to find it after it is displaced to B, especially following a delay between hiding and retrieval. Experiment 1 manipulated auditory input by keeping the hidden object audible versus silent, and visual input by presenting the delay in the light versus dark. Infants succeeded more at B with audible than silent objects and, unexpectedly, more after delays in the light than dark. Experiment 2 presented both the delay and search phases in darkness. The unexpected light-dark difference disappeared. Across experiments, the presence of auditory input helped infants find displaced objects, whereas the absence of visual input did not. Sound might help by strengthening object representation, reducing memory load, or focusing attention. This work provides new evidence on when bimodal input aids object processing, corroborates claims that audiovisual processing improves over the first year of life, and contributes to multisensory approaches to studying cognition. Statement of contribution What is already known on this subject Before 9 months, infants use sound to retrieve a stationary object hidden by darkness but not one hidden by occlusion. This suggests they find auditory input more salient in the absence of visual input in simple search tasks. After 9 months, infants' object processing appears more sensitive to multimodal (e.g., audiovisual) input. What does this study add? This study tested how audiovisual input affects 10-month-olds' search for an object displaced in an AB task. Sound helped infants find displaced objects in both the presence and absence of visual input. Object processing becomes more sensitive to bimodal input as multisensory functions develop across the first year.

Picturing objects in infancy.

Infants' transfer of information from pictures to objects was tested by familiarizing 9-month-olds (N = 31) with either a color or black-and-white photograph of an object and observing their preferential reaching for the real target object versus a distractor. One condition tested object recognition by keeping both objects visible, and the other tested object representation by hiding both objects. On visible trials, infants reached more for the distractor, indicating they recognized the target object from its picture. On hidden trials, infants reached more for the target object, suggesting they formed a continued representation of the object based on its picture. Photograph color had no effect. Infants thus show picture-to-object transfer by 9 months with preferential reaching, even with black-and-white pictures.

Disappearing Décalage: Object Search in Light and Dark at 6 Months.

Infants search for an object hidden by an occluder in the light months later than one hidden by darkness. One explanation attributes this décalage to easier action demands in darkness versus occlusion, whereas another attributes it to easier representation demands in darkness versus occlusion. However, search tasks typically confound these two types of demands. This article presents a search task that unconfounds them to better address these two explanations of the "dark advantage." Objects were hidden by submersion in liquid instead of occlusion with a screen, allowing infants to search with equally simple actions in light versus dark. In Experiment 1, 6-month-olds unexpectedly showed a dark disadvantage by discriminating when an object was hidden in the light but not the dark. Experiment 2 addressed the possibility that representation demands were higher in the dark than the light and showed that infants' search in the dark increased to match that in the light, but not exceed it. Six-month-olds can thus search for a hidden object both when action demands are simplified and when a noncohesive substance rather than a cohesive occluder hides the object, supporting aspects of both action-demand and representation-demand explanations of décalage in search behavior.

Something old, something new: a developmental transition from familiarity to novelty preferences with hidden objects.

Novelty seeking is viewed as adaptive, and novelty preferences in infancy predict cognitive performance into adulthood. Yet 7-month-olds prefer familiar stimuli to novel ones when searching for hidden objects, in contrast to their strong novelty preferences with visible objects (Shinskey & Munakata, 2005). According to a graded representations perspective on object knowledge, infants gradually develop stronger object representations through experience, such that representations of familiar objects can be better maintained, supporting greater search than with novel objects. Object representations should strengthen with further development to allow older infants to shift from familiarity to novelty preferences with hidden objects. The current study tested this prediction by presenting 24 11-month-olds with novel and familiar objects that were sometimes visible and sometimes hidden. Unlike 7-month-olds, 11-month-olds showed novelty preferences with both visible and hidden objects. This developmental shift from familiarity to novelty preference with hidden objects parallels one that infants show months earlier with perceptible stimuli, but the two transitions may reflect different underlying mechanisms. The current findings suggest both change and continuity in the adaptive development of object representations and associated cognitive processes.

Preschoolers' nonsymbolic arithmetic with large sets: is addition more accurate than subtraction?

Adult and developing humans share with other animals analog magnitude representations of number that support nonsymbolic arithmetic with large sets. This experiment tested the hypothesis that such representations may be more accurate for addition than for subtraction in children as young as 3(1/2)years of age. In these tasks, the experimenter hid two equal sets of cookies, visibly added to or subtracted from the sets, and then asked 3(1/2)-year-olds which set had more cookies. Initial set size was either large (7 or 9) or very large (18 or 30), and the final sets differed by either a high proportion (ratio of 1:2) or a low proportion (difference of 1 cookie). Children's addition performance exceeded chance, as well as their subtraction performance, across set sizes and proportions, whereas subtraction performance did not exceed chance. Arithmetic performance was also independent of counting ability. Addition performance was remarkably accurate when ratios between outcomes were close to 1, in contrast to previous findings. Interpretations for the asymmetry between addition and subtraction are discussed with respect to the nature of representations for nonsymbolic arithmetic with large sets.

The sound of darkness: why do auditory cues aid infants' search for objects hidden by darkness but not by visible occluders?

In manual search tasks designed to assess infants' knowledge of the object concept, why does search for objects hidden by darkness precede search for objects hidden by visible occluders by several months? A graded representations account explains this décalage by proposing that the conflicting visual input from occluders directly competes with object representations, whereas darkness merely weakens representations. This study tests the prediction that representations of objects hidden by darkness are strong enough for infants to bind auditory cues to them and support search, whereas representations of objects hidden by occluders are not. Six-and-half-month-olds were presented with audible or silent objects that remained visible, became hidden by darkness, or became hidden by a visible occluder. Search required engaging in the same means-end action in all conditions. As predicted, auditory cues increased search when objects were hidden by darkness but not when they were hidden by a visible occluder. Results are discussed in the context of different facets of object concept development highlighted by graded representations perspectives and core knowledge perspectives and in relation to other work on multimodal object representations.

Familiarity breeds searching: infants reverse their novelty preferences when reaching for hidden objects.

What infants appear to know depends heavily on how they are tested. For example, infants seem to understand object permanence (that objects continue to exist when no longer perceptible) within the first few months of life when this understanding is assessed through looking measures, but not until several months later when it is assessed through search measures. One explanation of such results is that infants gradually develop stronger representations of objects through experience, and that stronger representations are required for some tasks than for others. The current study confirms one prediction from this account: Stronger representations of familiar objects (relative to novel objects) should support greater sensitivity to their continued existence. After seeing objects hidden, infants reached more for familiar than novel objects, in striking contrast to their robust novelty preferences with visible objects. Theoretical implications concerning the origins of knowledge are discussed.

Detecting Transparent Barriers: Clear Evidence Against the Means-End Deficit Account of Search Failures.

The standard explanation of infants' search failures with hidden objects, despite an apparent sensitivity to them, is a deficit in the means-end skill for retrieving objects from occluders. Studies equating means-end demands for retrieving toys from transparent and opaque barriers challenge this account by showing that infants succeed more with visible objects. However, they suffer from a critical limitation: Infants may retrieve visible objects without noticing the transparent barriers in front of them. We addressed this concern by requiring infants to notice a barrier to retrieve a toy and specifically to pull down a rotating screen to retrieve a toy from behind it. Seven-month-olds used this means-end skill more often with a transparent barrier than an opaque one. Thus, neither a means-end deficit nor an ability to ignore transparent barriers fully accounts for search failures. Relations to other findings challenging the means-end deficit account and implications for approaches to studying cognitive development are discussed.

The Effects of Graded Occlusion on Manual Search and Visual Attention in 5- to 8-Month-Old Infants.

Young infants may be limited in searching for hidden objects because they lack the means-end motor skill to lift occluders from objects. This account was investigated by presenting 5- to 8-month-old infants with objects hidden behind transparent, semitransparent, and opaque curtains. If a means-end deficit explains search limitations, then infants should search no more for an object behind a transparent curtain than for objects behind semitransparent or opaque curtains. However, level of occlusion had a significant effect on manual search and visual attention. Infants retrieved and contacted the object more, contacted the curtain more, and looked away less with the transparent curtain than with the semi transparent or opaque curtains. Adding a time delay before allowing search and presenting a distraction after occlusion further depressed infants' behavior. The findings fail to support the means-end deficit hypothesis, but are consistent with the account that young infants lack object permanence.

Object Permanence in Five-and-a-Half-Month-Old Infants?

Event Set × Event Set designs were used to study the rotating screen paradigm introduced by Baillargeon, Spelke, and Wasserman (1985). In Experiment 1, 36 5 1/2-month-old infants were habituated to a screen rotating 180° with no block, a screen rotating 120° up to a block, or a screen rotating 180° up to and seemingly through a block. All infants were then tested on the same 3 events and also a screen rotating 120° with no block. The results indicate that infants are using novelty and familiarity preference to determine their looking times. To confirm this, in Experiment 2, 52 5 1/2-month-old infants were familiarized on either 3 or 7 trials to a screen rotating 180° with no block or a screen rotating 120° with no block. All infants were then tested on the same test events as in Experiment 1. Infants with fewer familiarization trials were more likely to prefer the familiar rotation event. The results of these 2 experiments indicate that infants did not use the possibility or impossibility of events but instead used familiarity or novelty relations between the habituation events and the test events to determine their looking times, and suggest that the Baillargeon et al. study should not be interpreted as indicating object permanence or solidity knowledge in young infants.