Examining the limits of Memory-Guided Planning in 3- and 4-year olds

Inhibitory control and memory guided planning during early childhood

Flexibly using memories to guide planning behavior is critical for typical functioning, yet little is known of how this ability emerges and the mechanisms supporting performance. The current study examined children's ability to generalize during memory-guided planning in a sample of 76 preschoolers (24 2-year-olds, M = 32.21 months, SD = 2.21, 12 girls; 27 3-year-olds, M = 41.37 months, SD = 3.50, 17 girls; and 25 4-year-olds, M = 54.64 months, SD = 3.29, 6 girls). Results suggested that 3 and 4-year-olds can flexibly apply a memory from one context to another, while 2-year-olds struggle to generalize. Further, individual differences in inhibitory control predicted performance during memory-guided planning, providing a potential mechanism supporting its early development.

Time from structure: Children infer the temporal order of past events from visual arrays

The current locations of objects are informative about the temporal order of past events. For example, by simply examining the locations of objects underground, geologists and historians can determine their relative ages. In three experiments, we explored the development of this ability to infer time from structure in children 3-6-years of age (N = 317). In all experiments, children saw pictures of object arrays (e.g., a stack of blocks) and selected the item placed first or last. Children in the final experiment also made judgments about the future (e.g., "Which block will they pick up first?"). By age 5, children were mostly accurate at inferring the order of past events. Children were more accurate when inferring first than last, and when inferring the future than the past. The findings suggest that children infer history by simulating how past events unfolded, and that 3-4-year-olds may struggle to perform these simulations.

Three- and four-year-old children represent mutually exclusive possible identities

How do children think about and plan for possible outcomes of events that could happen in the future? Previous work that has investigated children's ability to think about mutually exclusive possibilities has largely focused on children's reasoning about one type of possibility-the possible locations of an object. Here, we investigated children's reasoning about another type of possibility-mutually exclusive possible identities. In two experiments (N = 201 U.S. 3- and 4-year-olds), children were told that two animal characters (e.g., a bunny and a monkey) were going to take turns sliding down a playground slide. Children were told that the animals wanted to eat their favorite foods (e.g., carrots and bananas, respectively) as soon as they got to the bottom of the slide. In an Unambiguous Identity condition, we told children the identity of the animal that would slide down. In an Ambiguous Identity condition, we told children that which animal would slide down first was unknown. To examine children's representations of possible identities, we asked children to "get snack ready." We found that children in the Unambiguous Identity condition selected only one of the snacks (i.e., the favorite snack of the animal they were told would slide down), whereas children in the Ambiguous Identity condition selected both snacks, suggesting that they were accounting for both possible identities. These results extend the literature on the development of modal reasoning to include reasoning about possible identities and suggest that this ability may be available to children as young as 3 years.

Relationship between maternal grit and effortful control among 18-21-month-old toddlers

Grit is known to be effective for long-term academic and social success. However, few studies have focused on the role of grit in parenting and its effect on the development of grit in children. Therefore, this study investigated the effect of maternal grit on children's effortful control (EC), which is thought to be a precursor to grit, using parenting as a mediating factor. Participants in the current study were 412 children (age range: 18-21 months, M = 34.67 months, SD = 4.51 months) and their mothers. We assessed maternal grit, parenting style, maternal EC, and child EC, and found that maternal grit, maternal EC, and parenting style were positively correlated with child EC. Furthermore, maternal grit was related to EC in children not only directly, but also indirectly through responsive parenting. Additionally, maternal grit was found to be directly related to child EC only when assessed separately from maternal EC. The current study's findings suggest that maternal grit is directly related to EC in children in a way that differs from the mother's EC in child-rearing situations.

Three-year-olds' ability to plan for mutually exclusive future possibilities is limited primarily by their representations of possible plans, not possible events

The ability to prepare for mutually exclusive possible events in the future is essential for everyday decision making. Previous studies have suggested that this ability develops between the ages of 3 and 5 years, and in young children is primarily limited by the ability to represent the set of possible outcomes of an event as "possible". We tested an alternative hypothesis that this ability may be limited by the ability to represent the set of possible actions that could be taken to prepare for those possible outcomes. We adapted the inverted y-shaped tube task of Redshaw and Suddendorf (2016), in which children are asked to catch a marble that is dropped into the top of the tube and can emerge from either the left or right branch of the tube. While 4-year-olds typically place their hands under both openings to catch the marble, preparing for both possible outcomes (optimal action), 3-year-olds often cover only one opening, preparing for only one possible outcome (suboptimal action). In three Experiments, we asked whether first showing children the set of possible actions that could be taken on the tube would enable them to recognize the optimal action that should be used to catch the marble (Experiments 1 and 3, total n = 99 US 3- and 4-year-olds) and enable them to use the optimal action themselves (Experiment 2, n = 96 US 3- and 4-year-olds). We found that 3- and 4-year-olds performed similarly when they were given the opportunity to observe the set of possible actions beforehand. These findings suggest that 3-year-olds' competence at representing mutually exclusive possibilities may be masked by their developing ability to represent and deploy plans to act on these possibilities.

Extended trajectory of spatial memory errors in typical and atypical development: The role of binding and precision

Spatial reconstruction, a method for evaluating how individuals remember the placement of objects, has traditionally been evaluated through the aggregate estimation of placement errors. However, this approach may obscure the nature of task errors. Specifically, recent data has suggested the importance of examining the precision of responses, as well as absolute performance on item-context bindings. In contrast to traditional analysis approaches based on the distance between the target and the reconstructed item, in this study we further explored three types of errors (swap error, global error, and local distance) that may all contribute to the distance, with particular emphasis on swap errors and local distance due to their associations with item-context bindings and memory precision, respectively. We examined these errors in children aged 3-18 years, making comparisons between children with typical development (TD) and children with Down syndrome (DS), a population with known memory challenges. As expected, older children outperformed younger children in terms of overall memory accuracy. Of importance is that we measured uneven maturational trajectories of memory abilities across the various error types. Specifically, both remembered locations (irrespective of object identity) and swap errors (object-location binding errors) align with the overall memory accuracy. Memory precision, as measured by local distance in simpler set size 2 trials, mirrored overall memory accuracy. However, for more complex set size 3 trials, local distance remained stable before age 8 and showed age-related change thereafter. The group with DS showed reduced precision compared to a TD matched group, and measures of precision, and to a lesser extent binding errors, correlated with standard neuropsychological outcomes. Overall, our study contributed to a fine-grained understanding of developing spatial memory ability in a large sample of typical developing children and a memory impaired population. These findings contribute to a growing body of research examining precision as a key factor in memory performance.

"Plan chunking" expands 3-year-olds' ability to complete multiple-step plans

The ability to use knowledge to guide the completion of goals is a critical cognitive skill, but 3-year-olds struggle to complete goals that require multiple steps. This study asked whether 3-year-olds could benefit from "plan chunking" to complete multistep goals. Thirty-two U.S. children (range = 35.75-46.59 months; 18 girls; 9 white, 3 mixed race, 20 unknown; tested between July 2020 and April 2021) were asked to complete "treasure maps," retrieving four colored map pieces by pressing specific buttons on a "rainbow box." Children completed more of the four-step sequence correctly when the steps were presented in a way that encouraged chunking the steps into pairs. These findings suggest a potential mechanism supporting memory-guided planning abilities in early childhood.

Tracking what went where across toddlerhood: Feature-location bound object representations in 2- to 3-year-olds' working memory

Two experiments examined the development of the ability to encode, maintain, and update integrated representations of occluded objects' locations and featural identities in working memory across toddlerhood. Sixty-eight 28- to 40-month-old US toddlers (13 Asian or Pacific Islander, 6 Black, 48 White, 1 multiracial; 40 girls; tested between February 2015 and July 2017) tracked the locations of different color beads that were hidden simultaneously (Experiment 1) or sequentially (Experiment 2). Toddlers' ability to reliably store feature-location bound object representations in working memory varied as a function of age, memory load, and task demands. These results bridge a developmental gap between infancy and early childhood and provide new insights into sources of limitation and developmental change in children's early object representational capacities.

3-4-year-old children’s memory flexibility allows adaptation to an altered context

Imitation provides a reliable method to investigate the developing memory functions in childhood. The present study explored whether 3-4-year-old children are able to revise their previous experiences after a 1 week delay in order to adapt to an altered context. We used a combined short-term (Session 1) and delayed (Session 2) imitation paradigm based on a previous study with 2-year-olds. The constraints (target object close/far) and relatedly the relevance of using a tool in a goal attainment task (irrelevant/relevant, respectively) changed between the sessions. We found that children in Session 1 used the tool only when it was needed (relevant/object far context). After the 1 week delay when the tool was previously irrelevant and then became relevant, children remembered the irrelevant act and applied it in the altered context. When the tool lost its relevance after 1 week, children used the tool less than before, but did not fully omit it, despite its reduced efficiency. The present data with 3-year-olds was compared to a pattern of results with 2-year-olds (from a similar previous study), that allowed to discuss possible developmental transitions in memory and imitation. We propose that the flexible restoration of a formerly irrelevant act and the maintenance of a formerly successful solution indicate flexibility of preschooler’s memory when guiding imitation. This flexibility, however, interacts with children’s tendency to remain faithful to strategies that were previously ostensively demonstrated to them.

Two-year-olds use past memories to accomplish novel goals

Memory-guided planning involves retrieving relevant memories and applying that information in service of a goal. Previous studies have shown substantial development in this ability from 3 to 4 years of age. We investigated the emergence of memory-guided planning by asking whether 2-year-olds could draw on episodic memories of past experiences to generate and execute plans. In Experiments 1 and 2 (N = 32, ds > .7), 2-year-olds successfully did so, and this ability developed significantly across the third year of life. Furthermore, in Experiment 3 (N = 19, d = 0.63), 2-year-olds successfully applied episodic memories to guide plans in a novel problem context, suggesting flexibility in this ability. Together, these results suggest that some form of memory-guided planning emerges during the third year of life and may form the cognitive basis for episodic prospection later in development.

The Role of Executive Functions in Item Recognition and Temporal Order Memory Development

Item recognition and temporal order memory follow different developmental trajectories during middle childhood, with item recognition performance stabilizing and temporal order memory performance continuing to improve. We investigated the potential unique role of individual executive functions on item recognition and temporal order memory during this critical development period. Our results replicate and expand on previous findings, suggesting that executive functions, specifically inhibitory control and working memory, may be more crucial for successful temporal order memory than for item recognition during middle childhood.