V-VSS, June 1-2

Visual Memory

Talk Session: Wednesday, June 1, 2022, 6:30 – 8:00 pm EDT, Zoom Session

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Talk 1, 6:30 pm, 75.71

Distinct brain mechanisms of remembering individual events and their relationships

Yoko Higuchi1, Ethan Oblak1, Kazuhisa Shibata1; 1Center for Brain Science, RIKEN

When we remember events, we also form memories relating them to other events. However, how memories of these events and their relationships are processed in the brain remains poorly understood. Based on behavioral and functional magnetic resonance imaging (fMRI) experiments, we report that two different types of processing evolve over time in different brain areas. In a series of experiments, memories were assessed using a visual statistical learning paradigm. During the incidental encoding stage, participants were exposed to a stream of objects while performing a cover task. Unbeknownst to the participants, particular sequences of objects (e.g., ABC) were repeatedly presented. In the test stage, we conducted a surprise memory test to evaluate incidental memories of the exposed sequences. Our preliminary experiment confirmed findings of previous studies; participants acquired memories not only of the actual forward sequences, but also reversed sequences (e.g., CBA) that had never occurred during the encoding stage. In the main experiments, we tested whether participants were able to identify the memorized sequences from non-exposed sequences (memory identification) and to discriminate the forward and reverse sequences (memory discrimination) immediately after and one day after the encoding stage. We found significant decline in memory discrimination one day after the encoding stage while memory identification remained intact (Experiment 1). These results were replicated (Experiment 2), found to be time-dependent, rather than sleep-dependent (Experiment 3), and cannot be explained by mere forgetting of temporal order of the sequences due to the passage of time (Experiment 4). Using fMRI, we found that decreased memory discrimination was associated with activations in the right hippocampus (Experiment 5) while intact memory identification was associated with activations in the left hippocampus (Experiment 6). Our findings suggest that identification of individual memories and discrimination of these memories are subserved by different brain processing, rather than by one.

Acknowledgements: This work is supported by JSPS Grant Number 20J01411 and 20K14272 to YH, 19H01041, 20H05715, and JST Moonshot R&D JPMJMS2013 to KS.

Talk 2, 6:45 pm, 75.72

The linear impact of visual working memory load on visual awareness: Evidence from motion-induced blindness

Jiahan Yu1 (), Yiling Zhou1, Mowei Shen1, Hui Chen1; 1Zhejiang University

Despite the intimate relationship between visual working memory (VWM) and visual awareness, the question of how these two constructs interact with each other is still under debate. The current study sought to further clarify the nature of their relationship by investigating whether and how visual awareness is influenced by VWM load. In Experiment 1, participants were asked to perform a motion-induced blindness (MIB) task while simultaneously memorizing different numbers of items in VWM. The results showed that visual awareness was modulated by VWM load as the latency of MIB prolonged gradually as the VWM load increased and this modulation effect operated in a linear fashion. In Experiment 2, it is found that the visual working memory load does not affect the detection speed of the physical disappearance of the dot, eliminating the possibility that the modulation effect in Experiment 1 arose from the influence of VWM load on response criterion and/or cognitive speed.. Experiment 3 revealed that the modulation effect disappeared when asking participants only to report the number of items rather than maintaining them in their VWM, which ruled out another possibility that the observed modulation effect arose from some low-level mechanisms (e.g., physical differences due to different numbers of items, or processing load differences under different conditions). The above experiments showed that visual working memory load modulate the latency in MIB task in a linear manner. These findings have important implications for a better understanding of the nature of the relationship between visual awareness and VWM.

Acknowledgements: This work was supported by grants from National Science Foundation for Distinguished Young Scholars of Zhejiang Province, China (No. LR19C090002), National Natural Science Foundation of China (No. 32171046) and the Fundamental Research Funds for the Central Universities (2021FZZX001-06).

Talk 3, 7:00 pm, 75.73

Encoding-specificity instead of online integration of real-world spatial regularities for objects in VWM

Ruyi Liu1 (), Xinyang Liu1, Lijing Guo1, Piia Astikainen2, Chaoxiong Ye1,2; 1Institute of Brain and Psychological Sciences, Sichuan Normal University, China, 2Department of Psychology, University of Jyvaskyla, Finland

In daily life scenarios, most objects are not independent of each other; rather, they show a high degree of spatial regularity (e.g., beach umbrellas appear above beach chairs, not under them). Previous studies have shown a benefit of spatial regularities in visual working memory (VWM) performance of real-world objects, termed the spatial regularity effect (e.g., Kaiser et al., 2015). However, the mechanisms underlying this effect remain unclear. The spatial regularity effect can be explained by an ‘encoding-specificity’ hypothesis or a ‘perception-alike’ hypothesis. The former suggests that spatial regularity will enhance the visual encoding process but will not operate in information integration during VWM maintenance, while the latter suggests that spatial regularity will play a role in both the visual encoding and VWM maintenance processes. We tested these two hypotheses by investigating whether VWM integrates sequentially presented real-world objects by focusing on the existence of the spatial regularity effect. In Experiment 1, we manipulated the presentation (simultaneous vs. sequential) and regularity (with vs. without regularity) of memory arrays among pairs of real-world objects. The spatial regularity of memory objects improved the VWM performance in simultaneous presentation trials, but not in sequential presentation trials. In Experiment 2, we examined whether memory load hindered the spatial regularity effect in sequential presentation trials. We again found an absence of the spatial regularity effect, regardless of the memory load. These results suggest that participants were unable to integrate real-world objects into pairs based on spatial regularity during the VWM maintenance process. Therefore, the present results support the “encoding-specificity” hypothesis, implying that although the spatial regularity of real-world objects can enhance the efficiency of the encoding process in VWM, VWM cannot exploit spatial regularity to help organize sampled sequential information into meaningful groups.

Acknowledgements: This work was supported by grants from the National Natural Science Foundation of China (31700948), and the Academy of Finland (333649).

Talk 4, 7:15 pm, 75.74

Categorical bias, inter-item interaction, and serial dependence in visual working memory

Gi-Yeul Bae1 (); 1Arizona State University

Previous studies demonstrated that visual representations in working memory (WM) are biased by three factors: 1) the categorical structure of the stimulus space (i.e., categorical bias), 2) the other representations held in WM (i.e., inter-item bias), and 3) the previous-trial stimulus/response (i.e., serial dependence). Because the majority of previous studies have investigated these biases independently, it is unknown how they might interact in WM. The present study investigated the interaction between the three sources of WM bias. Experiment 1 used an orientation delayed estimation task for two items to investigate the interaction between categorical bias and inter-item bias. In the analysis, I measured the categorical bias separately for the trials where the two biases repulse a given item in the same direction (i.e., congruent trials) and the trials where they repulse a given item in the opposite direction (i.e., incongruent trials). I found that the categorical bias was completely canceled out by the inter-item bias in incongruent trials. Experiment 2 used a set-size one orientation delayed estimation task to investigate the relationship between categorical bias and serial dependence effect. Similar to Experiment 1, I assessed the serial dependence effect separately for the trials where the direction of the two biases was congruent and for the trials where they were incongruent. I found that the serial dependence effect was exaggerated in congruent trials but was reduced or even canceled out in incongruent trials. Together, the present study demonstrates that the three sources of bias influence each other, producing a systematic pattern of biases depending on specific stimulus features and their relationship. These results imply that WM may involve a process that integrates multiple sources of biases to support the current goal of the behavior and suggest that theories in WM cannot speak away these biases by appealing to random trial-to-trial variability.

Talk 5, 7:30 pm, 75.75

Attention without working memory: A feature-specific working memory gate for attended information

Hui Chen1 (), Ping Zhu1; 1Department of Psychology and Behavioral Sciences, Zhejiang University, Hangzhou, China

Previous studies regarded attention as the “gatekeeper” of visual working memory (VWM), with attended information being selected into VWM while unattended information being filtered. However, in most previous studies the attended information was also the to-be-remembered one, where attention and memory requirement was intertwined with each other. Here, we argued attention and VWM could be dissociated when requiring participants to attend to and use certain information to perform a task while not requiring them to remember it. Such information was termed as key feature, and we directly test whether the key feature has ever been encoded into VWM in Experiments 1-3 through a variety of paradigms. We found that the key feature could not produce a working memory-driven attentional bias effect (Experiment 1), consumed no VWM capacity (Experiment 2), and produced no CDA component (Experiment 3), indicating that the key feature, despite being fully attended and used, was not encoded into VWM. These results suggested a highly selective VWM gate enabling selection even among attended information. In Experiments 4-7, we further explored how the VWM gate worked to achieve selection among attended information. Specifically, when the key feature was attended, we forced participants to open the VWM gate by asking them to simultaneously memorize another item. Interestingly, we found that a key color would enter VWM when the memorized item was also a color (Experiments 4 and 5), but not when it was a shape (Experiment 6). Experiment 7 found that a key shape would enter VWM when the memorized item was also a shape. These results suggested a feature-specific VWM gate for attended information. That is, we could selectively open the color gate for one attended item while close the shape gate for another attended item. However, once the color gate is open, all attended colors would enter VWM.

Acknowledgements: This work was supported by grants from National Science Foundation for Distinguished Young Scholars of Zhejiang Province, China (No. LR19C090002), National Natural Science Foundation of China (No. 32171046) and the Fundamental Research Funds for the Central Universities (2021FZZX001-06).

Talk 6, 7:45 pm, 75.76

Search Strategies Modulate Memory-Driven Capture

Bo Yeong Won1 (), Weiwei Zhang1; 1University of California, Riverside

Working memory (WM) and attention often interact with each other. For instance, items maintained in WM can capture attention in visual search regardless of the task relevance of the memory items. The present study addresses whether memory-driven capture depends on search strategies. Specifically, we hypothesized that feature search mode that relies on top-down processes (e.g., goals) would produce more memory-driven capture than singleton search mode that relies on bottom-up processes (e.g., salience). Furthermore, memory-driven capture would be predicted by WM precision. Two experiments were conducted to encourage the feature search mode (Exp.1) in which the search target was defined by a specific shape (e.g., square) among three different shape distractors (e.g., circle, triangle, diamond) or the singleton search mode where the target was an odd shape (e.g., square) among three distractors (e.g., circles) with an identical shape. The visual search was inserted into the delay interval of a WM task in which the participants maintained a briefly presented color and then recalled it after the search trial. Critically, a color singleton appeared on some trials, producing three experimental conditions with different relationships between the singleton color and memory color. In the "Match" condition, the singleton color was the same as the memory color; in the "Nonmatch" condition, the singleton color was different from the memory color; in the "Absent" condition, no color singleton did appear. We found that the Match condition showed more robust attentional capture than the Nonmatch condition, suggesting a significant memory-driven capture, when participants adopted the feature search mode (Exp .1) but not the singleton search mode (Exp. 2). Furthermore, under the feature search mode, individuals with higher memory precision, measured from an independent memory recall task, showed more robust memory-driven capture. These results suggest that memory-driven capture is more involved in top-down than bottom-up attentional mechanisms.

Acknowledgements: NIMH grant (R01MH117132) to WZ