Navon Task¶
HED task ID: hedtsk_navon
Family: Conflict and interference tasks
Also known as: Global-Local Task, Navon Letters
Hierarchical letters in which large letters are composed of small ones; RT differences between global and local identification index attentional scope.
Description¶
The Navon Task investigates hierarchical processing in vision using compound stimuli—large (global) letters composed of smaller (local) letters (e.g., a large “H” made of small “S” letters). Participants identify either the global or local letter depending on instruction. The robust finding of global precedence shows faster identification of global than local forms, with global-to-local interference exceeding local-to-global interference. The task dissociates dorsal/ventral visual stream contributions and is sensitive to hemispheric specialization (left hemisphere for local, right for global processing).
Inclusion test¶
An experiment is an instance of this task when its procedure matches, it manipulates at least one of the listed variables, and it records at least one of the listed measures.
Procedure |
A large letter (global) composed of small letters (local) is presented; participants identify the letter at the designated level (global or local). |
Manipulation |
Target level (global vs. local); congruency (same vs. different letter at two levels); exposure duration; visual field. |
Measurement |
RT and accuracy; global precedence effect (faster global); asymmetric interference (global disrupts local more than reverse); congruency effect. |
Variations¶
Named versions that change what the participant experiences or does. The identifier
of a variation is hedvar_<task>__<variation>.
Variation |
Description |
Justification |
|---|---|---|
Standard Navon (Blocked)
|
Attend to global or local level in separate blocks. |
Canonical blocked global/local judgment of hierarchical figures |
Mixed/Cued Navon
|
Cue on each trial indicates which level to attend; measures switching between levels. |
Trial-by-trial cue indicates level; task-switching demand added |
Divided Attention Navon
|
Report both global and local identities. |
Respond to both levels simultaneously; different attentional demand |
Consistent vs. Inconsistent Stimuli
|
Same letter at both levels vs. different; inconsistent trials produce interference. |
Local and global levels same vs. different; conflict manipulation |
Sparse vs. Dense Local Elements
|
Number and spacing of local elements varies; affects global percept coherence. |
Number of local elements varies; tests density effect on global processing |
Emotional Navon
|
Faces or emotional expressions as compound stimuli. |
Emotional faces at global/local level; retained per §5.1 (EMOT retired) |
Auditory Navon Analogs
|
Hierarchically structured tone sequences; global melody vs. local intervals. |
Hierarchical auditory stimuli; different sensory modality |
Navon with Priming
|
Prior exposure to global or local level influences subsequent processing. |
Preceding prime influences level processing; temporal context manipulation |
Lateralized Presentation
|
Stimuli in left vs. right visual field to examine hemispheric effects. |
Stimuli presented to one visual field; tests hemispheric contributions |
Navon Figures with Shapes
|
Geometric shapes rather than letters; extends the paradigm beyond verbal stimuli. |
Non-letter shapes at global/local level; different stimulus class |
Temporal Precedence (Brief Exposure)
|
Very brief presentations (50–100 ms) to measure the time course of global vs. local availability. |
Brief exposure tests which level is processed first |
Cognitive processes¶
This task is designed to engage the following processes:
Key references¶
Navon, D. (1977). Forest before trees: The precedence of global features in visual perception. Cognitive Psychology, 9(3), 353–383. (DOI)
Kimchi, R. (1992). Primacy of wholistic processing and global/local paradigm: A critical review. Psychological Bulletin, 112(1), 24–38. (DOI)
Fink, G. R., Halligan, P. W., Marshall, J. C., Frith, C. D., Frackowiak, R. S. J., & Dolan, R. J. (1996). Where in the brain does visual attention select the forest and the trees? Nature, 382, 626–628. (DOI, PubMed)
Further references¶
Poirel, N., Pineau, A., & Mellet, E. (2008). What does the nature of the stimuli tell us about the global precedence effect? Acta Psychologica, 127(1), 1–11. (DOI, PubMed)
Beaucousin, V., Cassotti, M., Simon, G., Pineau, A., Kostova, M., Houdé, O., & Poirel, N. (2011). ERP evidence of a meaningfulness impact on visual global/local processing: When meaning captures attention. Neuropsychologia, 49(5), 1258–1266. (DOI, PubMed)
Gerlach, C., & Poirel, N. (2018). Navon’s classical paradigm concerning local and global processing relates systematically to visual object classification performance. Scientific Reports, 8, 324. (DOI, PubMed)
Förster, J., & Dannenberg, L. (2010). GLOMOsys: A systems account of global versus local processing. Psychological Inquiry, 21(3), 175–197. (DOI)
Kaur, J., & Paul, S. (2022). Global precedence changes by environment: A systematic review and meta-analysis on effect of perceptual field variables on global-local visual processing. Attention, Perception, & Psychophysics, 84, 1833–1877.
Song, Y., Hakoda, Y., & Sang, B. (2015). Lack of global precedence and global-to-local interference without local processing deficit in children with ADHD. Journal of Attention Disorders, 20(8), 671–682. (DOI, PubMed)
External links¶
Cognitive Atlas: global-local task