Relational memory weakness in autism despite the use of a controlled encoding task

Abstract

Introduction: Recent work challenged past findings that documented relational memory impairments in autism. Previous studies often relied solely on explicit behavioral responses to assess relational memory integrity, but successful performance on behavioral tasks may rely on other cognitive abilities (e.g., executive functioning) that are impacted in some autistic individuals. Eye-tracking tasks do not require explicit behavioral responses, and, further, eye movements provide an indirect measure of memory. The current study examined whether memory-specific viewing patterns toward scenes differ between autistic and non-autistic individuals.

Methods: Using a long-term memory paradigm that equated for complexity between item and relational memory tasks, participants studied a series of scenes. Following the initial study phase, scenes were re-presented, accompanied by an orienting question that directed participants to attend to either features of an item (i.e., in the item condition) or spatial relationships between items (i.e., in the relational condition) that might be subsequently modified during test. At test, participants viewed scenes that were unchanged (i.e., repeated from study), scenes that underwent an "item" modification (an exemplar switch) or a "relational" modification (a location switch), and scenes that had not been presented before. Eye movements were recorded throughout.

Results: During study, there were no significant group differences in viewing directed to regions of scenes that might be manipulated at test, suggesting comparable processing of scene details during encoding. However, there was a group difference in explicit recognition accuracy for scenes that underwent a relational change. Marginal group differences in the expression of memory-based viewing effects during test for relational scenes were consistent with this behavioral outcome, particularly when analyses were limited to scenes recognized correctly with high confidence. Group differences were also evident in correlational analyses that examined the association between study phase viewing and recognition accuracy and between performance on the Picture Sequence Memory Test and recognition accuracy.

Discussion: Together, our findings suggest differences in the integrity of relational memory representations and/or in the relationships between subcomponents of memory in autism.

Keywords: ASD; autism; episodic memory; eye tracking; relational memory.

Figure 1

Representative scene and associated orienting questions. (A) Example of a representative scene – the original scene, the version of that scene with an item manipulation, and the version of that scene with a relational manipulation. (B) Item (in blue) and relational (in orange) orienting question for the scene shown above (A).

Figure 2

Trial structure and event timing. (A) During Study Block 1, central fixation was followed by a scene (8 s). (B) During Study Block 2, central fixation was followed by a scene (5 s), accompanied by an orally presented orienting question to which participants responded via button press. (C) During the test block, central fixation was followed by a scene (6 s). Participants indicated via button press whether the scene was the “same,” “modified,” or “new” and provided a confidence rating, when prompted.

Figure 3

Yoking procedure at test. Representative example of a yoked scene during (A) study and (B) test for three different participants. Scenes during test were identical across participants but varied by encoding history.

Figure 4

Recognition memory for scenes and scene details. Corrected recognition accuracy for (A) memory for scenes index (percentage of novel hits – percentage of novel false alarms) by group. Corrected recognition accuracy for (B) memory for scene details index (percentage of modified hits – percentage of modified false alarms) by group and scene type. Error bars represent standard error of the mean.

Figure 5

Recognition memory for scenes and scene details for high confidence correct trials. (A) Memory for scenes (percentage of novel hits – percentage of novel false alarms) by group, limited to scenes identified correctly and with high confidence. (B) Memory for scene details (percentage of modified hits – percentage of modified false alarms) by group and scene type, limited to scenes identified correctly and with high confidence. Error bars represent standard error of the mean.

Figure 6

Proportion of total viewing time directed to the filled critical region of to-be-manipulated scenes in (A) Study Block 1 and (B) Study Block 2, subdivided by group and question type. Error bars represent standard error of the mean.

Figure 7

Proportion of total viewing time directed to the filled critical region of to-be-manipulated scenes in (A) Study Block 1 and (B) Study Block 2, subdivided by group and question type, and limited to the subset of scenes identified correctly and with high confidence. Error bars represent standard error of the mean.

Figure 8

Proportion of total viewing time directed to critical regions of scenes for (A) Memory for Repetition index (viewing to repeated scenes – viewing to novel scenes) and (B) Memory for Detail index (viewing to manipulated scenes – viewing to repeated scenes), subdivided by group, scene type, and critical region for scenes presented during Test Block. Error bars represent standard error of the mean.

Figure 9

Proportion of total viewing time directed to critical regions of scenes, subdivided by group, scene type, and critical region for scenes presented during Test Block, and limited to scenes that were identified correctly with high confidence. Error bars represent standard error of the mean.

Figure 10

First gaze duration (ms) to filled critical region of scenes for (A) Memory for Repetition index (viewing to repeated scenes – viewing to novel scenes) and (B) Memory for Detail index (viewing to manipulated scenes – viewing to repeated scenes), subdivided by group and scene type for scenes presented during Test Block. Error bars represent standard error of the mean.

Figure 11

First gaze duration (ms) to the filled critical region of scenes, subdivided by group and scene type during Test Block, and limited to scenes identified correctly and with high confidence. Error bars represent standard error of the mean.