SCDT
Scene Change Detection Task — Visual Working Memory · Change Blindness · Attentional Deployment
The Scene Change Detection Task (SCDT) assesses visual working memory (VSTM) capacity and susceptibility to change blindness — the failure to consciously register object changes across scene interruptions. A validated index of visuospatial short-term storage and attentional deployment.
Task Paradigm
Participants view a naturalistic scene containing four target objects (Study phase, exactly 5 s — fixed duration), then a gray mask (1 s), then a test scene that is either identical or contains one changed object. The participant indicates whether a change occurred. This paradigm directly probes the slot-model capacity limit of visual short-term memory.
Scoring System
Primary score: Total Correct (0–20). Secondary scores: mean correct-trial reaction time, error pattern categorization (clustered = consecutive failures on changed-scene trials, suggesting encoding failure; scattered = random errors, suggesting noise). Signal detection indices (d′, criterion) are computed to separate sensitivity from response bias.
Scientific Background
The change-blindness paradigms and slot-model literature the Scene Change Detection Task is built on. What a 4-item array can tell you about a brain. Cowan’s influential work established the K~3–4 capacity limit; the SCDT exploits this threshold to create a clinically sensitive measure.
Read the scientific background article →CHC Classification
- Primary ability: Gv — visuospatial processing
- Stratum: Visual memory span (MV)
- Secondary: Gs — processing speed (RT component)
Clinical Applications
- Neurocognitive screening batteries
- ADHD — attentional deployment assessment
- Traumatic brain injury monitoring
- Schizophrenia — visual working memory deficit index
- Aging and mild cognitive impairment