Children inhibit global information when the forest is dense and local information when the forest is sparse.

Visual environments are composed of global shapes and local details that compete for attentional resources. In adults, the global level is processed more rapidly than the local level, and global information must be inhibited in order to process local information when the local information and global information are in conflict. Compared with adults, children present less of a bias toward global visual information and appear to be more sensitive to the density of local elements that constitute the global level. The current study aimed, for the first time, to investigate the key role of inhibition during global/local processing in children. By including two different conditions of global saliency during a negative priming procedure, the results showed that when the global level was salient (dense hierarchical figures), 7-year-old children and adults needed to inhibit the global level to process the local information. However, when the global level was less salient (sparse hierarchical figures), only children needed to inhibit the local level to process the global information. These results confirm a weaker global bias and the greater impact of saliency in children than in adults. Moreover, the results indicate that, regardless of age, inhibition of the most salient hierarchical level is systematically required to select the less salient but more relevant level. These findings have important implications for future research in this area.

The forest, the trees, and the leaves: Differences of processing across development.

To act and think, children and adults are continually required to ignore irrelevant visual information to focus on task-relevant items. As real-world visual information is organized into structures, we designed a feature visual search task containing 3-level hierarchical stimuli (i.e., local shapes that constituted intermediate shapes that formed the global figure) that was presented to 112 participants aged 5, 6, 9, and 21 years old. This task allowed us to explore (a) which level is perceptively the most salient at each age (i.e., the fastest detected level) and (b) what kind of attentional processing occurs for each level across development (i.e., efficient processing: detection time does not increase with the number of stimuli on the display; less efficient processing: detection time increases linearly with the growing number of distractors). Results showed that the global level was the most salient at 5 years of age, whereas the global and intermediate levels were both salient for 9-year-olds and adults. Interestingly, at 6 years of age, the intermediate level was the most salient level. Second, all participants showed an efficient processing of both intermediate and global levels of hierarchical stimuli, and a less efficient processing of the local level, suggesting a local disadvantage rather than a global advantage in visual search. The cognitive cost for selecting the local target was higher for 5- and 6-year-old children compared to 9-year-old children and adults. These results are discussed with regards to the development of executive control. (PsycINFO Database Record

You can detect the trees as well as the forest when adding the leaves: evidence from visual search tasks containing three-level hierarchical stimuli.

The present study investigated how multiple levels of hierarchical stimuli (i.e., global, intermediate and local) are processed during a visual search task. Healthy adults participated in a visual search task in which a target was either present or not at one of the three levels of hierarchical stimuli (global geometrical form made by intermediate forms themselves constituted by local forms). By varying the number of distractors, the results showed that targets presented at global and intermediate levels were detected efficiently (i.e., the detection times did not vary with the number of distractors) whereas local targets were processed less efficiently (i.e., the detection times increased with the number of distractors). Additional experiments confirmed that these results were not due to the size of the target elements or to the spatial proximity among the structural levels. Taken together, these results show that the most local level is always processed less efficiently, suggesting that it is disadvantaged during the competition for attentional resources compared to higher structural levels. The present study thus supports the view that the processing occurring in visual search acts dichotomously rather than continuously. Given that pure structuralist and pure space-based models of attention cannot account for the pattern of our findings, we discuss the implication for perception, attentional selection and executive control of target position on hierarchical stimuli.

Do you want to see the tree? Ignore the forest: inhibitory control during local processing: a negative priming study of local-global processing.

The visual environment consists of global structures (e.g., a forest) made up of local parts (e.g., trees). When compound stimuli are presented (e.g., large global letters composed of arrangements of small local letters), the global unattended information slows responses to local targets. Using a negative priming paradigm, we investigated whether inhibition is required to process hierarchical stimuli when information at the local level is in conflict with the one at the global level. The results show that when local and global information is in conflict, global information must be inhibited to process local information, but that the reverse is not true. This finding has potential direct implications for brain models of visual recognition, by suggesting that when local information is conflicting with global information, inhibitory control reduces feedback activity from global information (e.g., inhibits the forest) which allows the visual system to process local information (e.g., to focus attention on a particular tree).