Abstract
Most studies of visual search across the life span have focused on classic feature and conjunction searches in which observers search for a fixed, simple shape target among relatively homogeneous distractors over a block of multiple trials. In the present study, we examine a more realistic task in which participants (4 to 25 years-old) look for images of real objects, presented amongst a heterogeneous array of other objects. The target is unique on every trial, unlike in previous developmental studies of visual search. Our new touchscreen-based “Pirate-Treasure” search also allows the testing of younger children within a video-game-like task. With this method, we tested a large sample (n = 293) of typically developing children and young adults. We assessed the developmental course of different search metrics like search efficiency, motor response differences, and accuracy (misses and false-alarm errors). Results show the most rapid time courses in development for accuracy. Search slopes reach the young adult level most slowly. The intercepts of the Reaction Time (RT) × Set Size function are often attributed to nonsearch perceptual and motor components of the task. The intercept time course is intermediate between accuracy and slope. Interestingly, these developmental functions follow time courses proposed in neuropsychological models of executive function development. This suggests that a single, video-game-like search task could be useful in routine assessments of cognitive development.
Highlights
Most studies of visual search across the life span have focused on classic feature and conjunction searches in which observers search for a fixed, simple shape target among relatively homogeneous distractors over a block of multiple trials
Typical measures are the mean response time (RT), the slope and intercept of the Reaction Time (RT) × Set Size functions, and accuracy—both misses and false-alarm errors. These tasks have been extremely useful, but they differ in important ways from search tasks that might be important in daily life
This paper reports on the first large developmental study of unique object search
Summary
Most studies of visual search across the life span have focused on classic feature and conjunction searches in which observers search for a fixed, simple shape target among relatively homogeneous distractors over a block of multiple trials. The aim is to compare different developmental changes from 4 to 25 years of age in a large sample of participants (293) to track the time course of cognitive processes immersed in a unique real-world object search. Many studies have found that children’s conjunction search RTs are longer, and the slope of the RT ×Set Size functions are steeper This is often taken to show immaturity in the development of topdown attentional control processes (Donnelly et al, 2007; Merrill & Conners, 2013; Michael et al, 2013; Trick & Enns, 1998; Woods et al, 2013). Some of the studies reporting steeper RT × Set Size functions used a younger sample (e.g., Ruskin & Kaye, 1990, compared 5-year-olds to 6-year-olds and 11-year-olds to 12-year-olds), others have found relatively steep RT × Set Size functions for somewhat older children (e.g., Lobaugh, Cole, & Rovet, 1998, comparing 7-year-olds to 8-year-olds and adults; Trick & Enns, 1998, comparing 6-year-olds and 22-year-olds). Donnelly et al (2007) proposed that conjunction search was more effortful because children have not yet developed the ability to “guide” search, while Woods et al (2013) attribute age-related improvement in conjunction search to the processes of maturation in the development of the dorsolateral prefrontal cortex (DLPFC), since the DLPFC is implicated in executive functions involved in organizing visual search
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