The Effect Of Navigational Affordance On Episodic Memory And Its Cognitive Neural Mechanisms

Navigational affordance refers to aspects of our environment that allow us to evaluate where we can and cannot go,such as wall boundaries and doorways.Previous research has found that scene context plays an important role in episodic memory,but it is unclear how navigational affordances affect it,and in particular whether shared or dissociated mechanisms exist to the processing of item and source memory.To address this question,the present study conducted four experiments investigating how navigational affordances impact item memory and source memory—two important components of episodic memory for object and scene cues,and further investigating how navigational affordances impact eye movements and the electrophysiological responses to episodic memory.In Experiment 1,we used study-recognition paradigm in which subjects were asked to learn a series of scenes in the study phase,followed by a brief distraction task,and then were asked to select the correct scene in which the object was located(source memory)or the correct object which the scene contained(item memory)in the recognition task.We found that source memory has better response to navigational affordances.Similarly,participants were more likely to choose the correct objects in the condition of navigational affordances for item memory.We demonstrate that at low processing load,navigational affordances can enhance both two components of episodic memory.In Experiment 2,we manipulated object relations to increase the difficulty to investigate whether the promotion effect will be affected by the task processing load.We found that navigational affordances still enhanced source memory at high processing load.Interestingly,there was a significant interaction between navigational affordances and object relations.That is,participants recalled relation of ON significantly more than IN relation in the navigation affordances condition,whereas in the condition of non-affordance,IN relation was recalled significantly more than ON relation.In contrast,navigational affordances had no promotion effect on item memory.We demonstrate that there is a dissociated mechanism to navigational affordances between source memory and item memory at high processing load.How does the navigational affordance guide eye movements responses to episodic memory? Based on the behavioral results of experiment 2,we recorded eye movements while participants memorized images of real-world scenes aimed to explore the cognitive mechanisms in experiment 3.The results showed that navigational affordances can affect eye movements towards object and scene context.Specifically,we observed a robust gaze bias towards scene context at navigational affordances condition,while gaze bias towards objects at non-affordance condition.Participants observed object relations later at encoding phase,and devoted more time and fixations to IN relations than ON relations.Secondly,we observed a significant interaction between object relations and navigational affordances for dwell time.Specifically,total fixation time was significantly longer for the IN relation than for the ON relation at non-affordance condition,whereas there was no difference at navigational affordances condition.In Experiment 4,we investigated how navigational affordances impact the electrophysiological responses to episodic memory by EEG.In order to better control navigation affordances visually,we added control condition of scenes with oil paintings to observed participants’ brain activity during encoding and retrieval phase.Subjects memorized the scene pictures presented and then completed the scene recall test based on the object cue priming.ERPs revealed that,during the encoding phase,the navigational affordances evoked a larger P2,while the oil painting scenes evoked a larger P3.For P3 component,the interaction between scene types and object relations reached a marginal significance,that is,only for navigational affordances,IN relation reporting lower P3 amplitude than ON relation.In the retrieval phase,navigational affordances evoked a larger N170,while the closed scene evoked a smaller P3.The main conclusions are as follow: Firstly,navigational affordances can enhance episodic memory,but at high processing load,there is a dissociated mechanism to navigational affordances between source memory and item memory.Secondly,individuals processing the scenes is top-down.They focus more time on objects in the early stage,and the attention patterns change with navigational affordances.Moreover,individuals observed object relations later at encoding phase.Thirdly,from the neural mechanisms,individuals process the non-affordances(oil painting scenes and closed scenes)earlier than navigational affordances at encoding phase.In memory retrieval,individuals extract category information with navigational affordances better than non-affordances(N170).Compared with scenes with doors and oil paintings,individuals lack of confidence about closed scenes in the memory recall(P3).Besides,subjects recall the oil painting scenes according to color perception(LPN).Taken together,this study not only contributes to further understanding of the scenes scaffold effects of episodic memory,but also suggests similarities and differences in the processing mechanisms of the dual visual pathways,advancing the field of episodic and spatial memory.