A Spatial-Context Effect in Recognition Memory

Abstract

We designed a novel experiment to investigate the modulation of human recognition memory by environmental context. Human participants were asked to navigate through a four-arm Virtual Reality (VR) maze in order to find and memorize discrete items presented at specific locations in the environment. They were later on tested on their ability to recognize items as previously presented or new. By manipulating the spatial position of half of the studied items during the testing phase of our experiment, we could assess differences in performance related to the congruency of environmental information at encoding and retrieval. Our results revealed that spatial context had a significant effect on the quality of memory. In particular, we found that recognition performance was significantly better in trials in which contextual information was congruent as opposed to those in which it was different. Our results are in line with previous studies that have reported spatial-context effects in recognition memory, further characterizing their magnitude under ecologically valid experimental conditions.

Keywords: context effects; recognition memory; spatial behavior; spatial memory and navigation; virtual reality.

Figure 1

Task description. (A) A view showing the spatial layout of the maze. Four satellite rooms are connected to a central one. (B) Twenty items are positioned in one of the walls in each room forming a 5 × 4 matrix. The target room at each trial is indicated in the top right of the user interface (UI) with a texture. (C) Schematic showing a trial in each of the phases of the experiment.

Figure 2

Recognition performance. (A) Performance as a function of proportion of trials correctly and incorrectly identified. Each point is one session (n = 33); red point indicates the mean performance. (B) Behavioral Receiver Operating Characteristic (ROC) curve for individual sessions (gray) and average (red). Each data point is a different confidence level. (C) Response probabilities for familiar and novel, correct and incorrect items. Error bars represent ± SE across subjects. (D) Normalized recognition accuracy was significantly higher in trials recognized with high confidence compared to low confidence trials. ***P ≤ 0.001. P values are corrected for multiple comparisons.

Figure 3

Navigation performance. (A) Mean time of all participants in each room. Error bars represent ±SD across subjects. (B) Example trajectories from the same participant indicating different optimality values (green = 0.97, pink = 0.60). (C) Optimality in navigation as a function of trial number. Trial 80 marks the start of the testing block. Blue line represents mean optimality and shaded area the standard deviation. (D) Navigation optimality as a function of recognition accuracy. Blue line shows the least square fit.

Figure 4

Recognition performance for congruent and non-congruent items. (A) Normalized accuracy in non-congruent and congruent trials. (B) Decision Time (DT) for non-congruent and congruent trials. **P ≤ 0.01. P values are corrected for multiple comparisons.