Implicit, Long-Term Spatial Contextual Memory

1. Implicit, Long-Term Spatial Contextual Memory

2. Important Definitions • Explicit (declarative) memory- Supports the ability to consciously retrieve and declare past facts and events • Implicit (nondeclarative) memory- Supports improved performance in a variety of perceptual and motor tasks, although observers cannot recall or articulate learned information • Contextual cuing- Refers to improved performance in visual search tasks based on learned associations between targets and surrounding visual context.

3. Previous Research Target (sideways t) in a consistent location for various configurations in a set. Some configurations were repeated (OLD) and others were always new (NEW). Compared RTs in old and new configurations Configurations served as a predictive cue for the target’s location after a series of repetitions, about 5-10. Visual context cued attention to the target (implicit).

4. Previous Research: Limitations • Recognition test may not have accurately distinguished explicit vs. implicit memory • Need to clarify distinction between explicit vs. implicit memory in terms of spatial contextual cuing • Purpose: “Aim to provide converging evidence to further bolster the claim that spatial contextual cuing represents an implicit learning task that produces memory representations that are also implicit.”

5. Experiment 1 • The purpose of experiment 1 was to rule out alternative explanation of explicit memory in contextual cuing • Method: • 18 subjects • Basic search task: 24 blocks, 12 Old, 12 New, total of 576 trials to establish baseline RT • After trials are completed, E enters and sets up guessing task for target absence

6. Experiment 1: Results • Filtered out incorrect trials • Learning rate steeper for Old condition • Mean for guessing target locations in Old displays was not significantly better than chance (27%) • Implication: No evidence for explicit memory

7. Experiment 2 • Hypothesis: Explicit instructions would not improve accuracy for guessing target location • Method: • Identical to experiment 1 • Instruction phase before search task saying half displays would repeat, and it could benefit search • Warned that they would be asked about the displays at the end of the study

8. Experiment 2: Results • Search results reiterated from experiment 1 • Mean for guessing target location in Old displays was 23% • Implication: Explicit instruction did not lead to better learning of target location

9. Experiment 3 • Hypothesis: If contextual cuing is supported by implicit memory trace, memory for spatial context should persist over time • Method: • Identical to Experiment 1 • Session 1: 30 blocks of search Old/New • Session 2: One week later, 8 blocks of search + 1 block of explicit guessing • Monochromatic, distracters more similar to the target (sideways t)

10. Experiment 3: Results • Contextual cuing observed in session 1 • Search time was not significantly faster in session 2 • Accuracy for guessing was still at chance (~25%)

11. General Discussion • Research reinforces the claim that spatial contextual memory is implicit and long-term. • Even with all the manipulations (explicit instruction, week long delay), guessing task remained at chance. • Implicit spatial context memory may last at least 1 week. • Research shows that implicit and explicit memory involve different brain structures, but further research may be needed.

12. Questions/Ideas