Global-Local Processing Task
Navon hierarchical letter task examining global vs. local visual processing and attentional focus. Participants respond to either small letters or large letter shapes composed of smaller letters, testing the ability to selectively attend to different levels of hierarchical visual stimuli.
Participants view large letters (global level) composed of smaller letters (local level) and respond to target letters at either the global or local level depending on the block condition. For example, a large 'H' might be made of small 'S' letters. In global attention blocks, participants respond to the large letter shape; in local attention blocks, they respond to the small component letters. The task includes congruent trials (same letter at both levels), incongruent trials (different letters), and conditions with and without spatial scatter of the local elements. This design measures selective attention, the global precedence effect, and interference between processing levels.
Measures: Visual attention, global vs. local processing, hierarchical stimulus processing, selective attention, cognitive interference, global precedence effect
- Task includes multiple stimulus sets with different letter combinations
- Supports 7 languages: English, German, Spanish, French, Croatian, Italian, Dutch, Lithuanian, Portuguese, and Chinese
- Uses Layout system for responsive positioning and modern response handling
- Includes conditions with and without spatial scatter to manipulate grouping cues
- Provides detailed trial-by-trial feedback and block summaries
| testtype | Global image scheme. Can be dense (PEBL original), sparse, or McKone. (default: mckone) |
| fontsize | Font size to display local stimulus and to use as a template for the global stimulus (default: 35) |
| globalheight | Width in pixels of global stimulus (default: 350) |
| reps | Number of trials per condition in each block (default: 10) |
| stim1 | Stimulus for left response (default: H) |
| stim2 | Stimulus for right response (default: S) |
| stimdummy | Neutral dummy stimulus. Navon used more of a O. Could also try ▓█▄ (default: █) |
| giveErrorfeedback | Should error feedback be given on each trial (default: 1) |
| doscatterconditions | Should you include 'scatter' conditions as blocks 6/7 (spatial uncertainty) (default: 1) |
| scatterwidth | Width of x uncertainty in scatter blocks (default: 600) |
| scatterheight | Height of y uncertainty in scatter blocks (default: 0) |
| responsemode | Response method: auto (platform-aware), keyboardShift (L/R shift), keyboardSafe (Z/slash for web), arrowLR (left/right arrows), mousetarget (click targets), mousebutton (L/R mouse buttons), userselect (custom key) (default: auto) |
| Validation | validated |
| Psychometric data | Available |
| Normative data | Not available |