Infant research is hard. It is difficult, expensive, and time‐consuming to identify, recruit, and test infants. As a result, ours is a field of small sample sizes. Many studies using infant looking ...time as a measure have samples of 8–12 infants per cell, and studies with more than 24 infants per cell are uncommon. This paper examines the effect of such sample sizes on statistical power and the conclusions drawn from infant looking‐time research. An examination of the state of the current literature suggests that most published looking‐time studies have low power, which leads in the long run to an increase in both false positive and false negative results. Three data sets with relatively large samples (>30 infants) were used to simulate experiments with smaller sample sizes; 1,000 random subsamples of 8, 12, 16, 20, and 24 infants from the overall samples were selected, making it possible to examine the systematic effect of sample size on the results. This approach revealed that despite clear results with the original large samples, the results with smaller subsamples were highly variable, yielding both false positive and false negative outcomes. Finally, a number of emerging possible solutions are discussed.
The development of visual attention in infancy is typically indexed by where and how long infants look, focusing on changes in alerting, orienting, or attentional control. However, visual attention ...and looking are both complex systems that are multiply determined. Moreover, infants’ visual attention, looking, and learning are intimately connected. Infants learn to look, reflecting cascading effects of changes in attention, the visual system, and motor control as well as the information infants learn about the world around them. Furthermore, infants’ looking behavior provides the input infants use to perceive and learn about the world. Thus, infants look to learn about the world around them. A deeper understanding of development will be gained by appreciating the cascading effects of changes across these intertwined domains.
This Presidential Address is aimed at considering how infant development can be understood in terms of developmental cascades. Adopting a developmental cascades approach may be especially useful for ...understanding development in infancy, when changes occur in multiple domains over relatively short time spans. Thinking about change in terms of developmental cascades highlights the role of the input in development, both in terms of how the input changes with development and in terms of how differences in the input lead to different developmental pathways. I reflect on how a developmental cascade perspective can help us understand the role of input and how development builds as the emergence and refinement of abilities changes the input and shapes the developmental pathways. Further, I emphasize that infants develop despite differences in the input, and that when studying infant development we should seriously consider the diversity of experience that infants encounter and how differences in experience (and input) shape the developmental cascade.
How and when infants and young children begin to develop emotion categories is not yet well understood. Research has largely treated the learning problem as one of identifying perceptual similarities ...among exemplars (typically posed, stereotyped facial configurations). However, recent meta-analyses and reviews converge to suggest that emotion categories are abstract, involving high-dimensional and situationally variable instances. In this paper we consult research on the development of abstract object categorization to guide hypotheses about how infants might learn abstract emotion categories because the two domains present infants with similar learning challenges. In particular, we consider how a developmental cascades framework offers opportunities to understand how and when young children develop emotion categories.
Emotion categories are ad hoc abstract categories with highly variable instances that are constructed to meet situation-specific functions.Emotional development research has largely focused on the perception of exaggerated, posed facial configurations that depict stereotyped emotional expressions, and has not yet proposed or tested hypotheses about the mechanisms for learning abstract emotion categories.Research on abstract object categorization provides insights into how infants form context-specific, abstract categories that vary in their physical, functional, and psychological features.A developmental cascades approach provides a framework for guiding hypotheses about the formation of abstract emotion categories in the context of other developing abilities.Specifically, a developmental cascades approach proposes that emotion categories are the result of a dynamic, multicausal learning process that is conditioned on the development of motor, linguistic, and mental inference abilities, among other core processes.
Many aspects of infant development are assessed using infant looking times to visual and audiovisual stimuli. In this article, we describe a stand-alone software package that allows simultaneous ...stimulus presentation to infants and recording of their looking times via a keypress by a human observer. The software was developed to run both on 64-bit Intel-based Macs running Mac OS/X 10.10 (Yosemite) or later and on 64-bit Windows 7 and 10. It can present a variety of visual and/or auditory stimuli; is customizable with respect to how trials are initiated, how trial lengths are defined, and the phases of the experiment; and can be used to record looking times online or after the fact, as well as to assess the reliability of coding. The software is freely available at http://habit.ucdavis.edu.
Four experiments examined how faces compete with physically salient stimuli for the control of attention in 4-, 6-, and 8-month-old infants (N = 117 total). Three computational models were used to ...quantify physical salience. We presented infants with visual search arrays containing a face and familiar object(s), such as shoes and flowers. Six- and 8-month-old infants looked first and longest at faces; their looking was not strongly influenced by physical salience. In contrast, 4-month-old infants showed a visual preference for the face only when the arrays contained 2 items and the competitor was relatively low in salience. When the arrays contained many items or the only competitor was relatively high in salience, 4-month-old infants' looks were more often directed at the most salient item. Thus, over ages of 4 to 8 months, physical salience has a decreasing influence and faces have an increasing influence on where and how long infants look.
Visual attention develops rapidly and significantly during the first postnatal years. At birth, infants have poor visual acuity, poor head and neck control, and as a result have little autonomy over ...where and how long they look. Across the first year, the neural systems that support alerting, orienting, and endogenous attention develop, allowing infants to more effectively focus their attention on information in the environment important for processing. However, visual attention is a system that develops in the context of the whole child, and fully understanding this development requires understanding how attentional systems interact and how these systems interact with other systems across wide domains. By adopting a cascades framework we can better position the development of visual attention in the context of the whole developing child. Specifically, development builds, with previous achievements setting the stage for current development, and current development having cascading consequences on future development. In addition, development reflects changes in multiple domains, and those domains influence each other across development. Finally, development reflects and produces changes in the input that the visual system receives; understanding the changing input is key to fully understand the development of visual attention. The development of visual attention is described in this context.
We examined the relation between 4- to 12-month-old infants' (
= 107) motor development and visual preference for handled or non-handled objects, using Lookit (lookit.mit.edu) as an online tool for ...data collection. Infants viewed eight pairs of objects, and their looking was recorded using their own webcam. Each pair contained one item with an easily graspable "handle-like" region and one without. Infants' duration of looking at each item was coded from the recordings, allowing us to evaluate their preference for the handled item. In addition, parents reported on their infants' motor behavior in the previous week. Overall, infants looked longer to handled items than non-handled items. Additionally, by examining the duration of infants' individual looks, we show that differences in infants' interest in the handled items varied both by infants' motor level and across the course of the 8-s trials. These findings confirm infant visual preferences can be successfully measured using Lookit and that motor development is related to infants' visual preferences for items with a graspable, handle-like region. The relative roles of age and motor development are discussed.
Habituation of looking time has become the standard method for studying cognitive processes in infancy. This method has a long history and derives from the study of memory and habituation itself. ...Often, however, it is not clear how researchers make decisions about how to implement habituation as a tool to study processes such as categorization, object representation, and memory. This article describes the challenges for implementing this tool and describes a set of best practices for its use to study perception and cognition in infancy.
Adults’ visual attention is guided by the contents of visual short-term memory (VSTM). Here we asked whether 10-month-old infants’ (N = 41) visual attention is also guided by the information stored ...in VSTM. In two experiments, we modified the one-shot change detection task (Oakes, Baumgartner, Barrett, Messenger, & Luck, 2013) to create a simplified cued visual search task to ask how information stored in VSTM influences where infants look. A single sample item (e.g., a colored circle) was presented at fixation for 500 ms, followed by a brief (300 ms) retention interval and then a test array consisting of two items, one on each side of fixation. One item in the test array matched the sample stimulus and the other did not. Infants were more likely to look at the non-matching item than at the matching item, demonstrating that the information stored rapidly in VSTM guided subsequent looking behavior.
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