Modality-general Benefit Of Eye-closure On The Retrieval Of Intentionally Learned Information Part 1

Abstract

The beneficial effect of eye closure during retrieval was demonstrated in many studies addressing eyewitness memory or memory of episodic events. Fewer studies examined the effect concerning the intentional learning of verbal information. Furthermore, the question of whether the eye-closure result is modality-specific, boosting visual memory only, or modality-general, boosting also other forms of memory (e.g., auditory memory), is still open. 

Witnesses are often asked to give evidence after an accident or incident, which requires them to be able to accurately recall everything they saw. Eyewitness memory therefore has important legal and investigative implications. However, memory is a relatively abstract and personal concept, and many factors can affect a person's memory.

Research shows that a good memory can improve an individual's quality of life and success. When we can remember information about our experiences, we are better able to predict the future and make informed decisions. In addition to this, having a good memory can improve our learning and cognitive abilities, making us more confident and organized in our daily lives.

However, memory is not the same for everyone. Some people have stronger memories and can retain more information, while others have more difficulty retaining information. Many factors can affect a person's memory, including age, health, sleep quality, diet, and mental state, among others.

Still, there are ways to help improve your memory. Proper physical and brain exercise, including regular aerobic exercise, learning new skills, and mnemonic techniques, can improve memory. Additionally, sleep quality and diet can have a profound impact on memory. Maintaining a healthy lifestyle and a positive attitude can also help improve memory.

As a witness, it is crucial to be able to accurately recall what you saw. Without good memory, it is difficult for us to remember important details and provide authentic evidence. Therefore, in daily life, we should try our best to maintain a healthy lifestyle, learn new skills, and use memory techniques to improve our memory ability and credibility as an eyewitness. It can be seen that we need to improve memory, and Cistanche deserticola can significantly improve memory because Cistanche deserticola is a traditional Chinese medicinal material that has many unique effects, one of which is to improve memory. The efficacy of minced meat comes from the various active ingredients it contains, including acid, polysaccharides, flavonoids, etc. These ingredients can promote brain health in various ways.

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These issues were addressed in the present study. Participants (N = 129) were asked to study aurally and visually presented lists of unrelated nouns (within-subjects). During free recall, participants either kept their eyes open or closed their eyes (between-subjects). Eye closure resulted in better free recall than keeping the eyes open. 

Notably, this effect emerged for both visually and aurally presented word lists, suggesting that the effect of closing the eyes is rather modality-general. The results are discussed concerning the limitations of previous studies and practical implications.

KEYWORDS

eye-closure effect, intentional learning, long-term memory, modality-specificity, verbal memory, and visual distraction.

1| INTRODUCTION

When people try to remember something, they often look away or even close their eyes. Research demonstrated that people avert their gaze and close their eyes more often when they try to recall autobiographical facts and general knowledge that are difficult to retrieve and that this behavior promotes more correct answers (Glenberg et al., 1998; see also Radel & Fournier, 2017, for a replication). 

However, most studies so far revealing a positive effect of closing the eyes on retrieval addressed eye-witness memory (i.e., incidental learning of multimodal facts of episodes), assessed both in natural contexts and the laboratory (e.g., Perfect et al., 2008, 2012; Vredeveldt et al., 2011; Vredeveldt & Penrod, 2013; Wagstaff et al., 2004).

The eye-closure effect has been investigated less frequently in the recall of intentionally learned verbal information. In one study (Einstein et al., 2002), participants were presented aurally with word pairs. Cued recall after a short distractor task was better in the eye-closure condition and in a condition in which participants looked at a small cross on a blank computer screen, compared to a condition in which they looked at changing pictures on the screen. Thus, preventing visual distraction—as it usually occurs when scanning the environment with open eyes—improved retrieval. 

The effect of visual distraction on memory was already reported by Glenberg et al. (1998, Exp. 5), showing a better recall performance of words when participants looked at a simple (static picture) than at a complex (dynamic, silent movie) visual display. However, no eye-closure condition was realized in this study and only recall of the middle five items of each word list (but not of the first and last five words) was analyzed. 

Rae and Perfect (2014) tried to replicate and extend this experiment in a series of five experiments, revealing inconsistent results. The effect of simple versus complex visual distraction was confirmed for the midlist words but not for the first and last words of each list in Experiment 1, but not in Experiments 2 and 3, in which the presentation rate of the words and interference by presenting words of the same category was additionally manipulated. Unfortunately, again no closedeyes condition was realized (or it was subject to a coding error in Experiment 1, respectively).

The effect of eye closure on the recall of objects (and their number) was investigated in another study (Wais et al., 2010, Exp. 1). Participants were presented with pictures of objects that differed in their number (i.e., 1–4 objects per category). The first task was to judge whether each object would fit into a shoebox and whether they could carry the objects in their hands and arms. 

After 1 h, an unannounced cued-recall test followed by presenting participants with an auditory description of objects and asking them to decide whether the objects were shown before (“old”) or not (“new”), and to indicate the number of the old objects (i.e., recollection of details). During the test, participants closed their eyes and looked at a gray display, or pictures of scenes, serving as visual distractors. 

The visual distraction, compared to the other two conditions, impaired the correct recollection of the number of previously presented objects, and looking at a gray display or pictures of scenes impaired the identification of lures (i.e., false alarms). The identification of objects for which participants indicated an incorrect number was not affected by the visual distraction conditions. 

However, incidental rather than intentional learning was addressed in this study.

Similar findings were revealed by Parker and Dagnall (2020) who presented participants with pictures of objects to be studied and thereafter conducted a recognition test. Closing the eyes shortly before and after the visual presentation of the targets in this test increased correct recognition and reduced false alarms compared to keeping the eyes constantly open. 

In a more recent study, Parker et al. (2022) investigated the eye-closure effect and its interaction with working memory and processing capacity. Participants were first assigned to extreme (i.e., upper and lower quartile) digit span groups (Exp. 1) or extreme reading span groups (Exp. 2) and saw then two lists of words, each involving 25 words. After the presentation of each word list and a short distractor task, a verbal free recall test followed that was completed either with open or closed eyes (manipulated within subjects). 

In both experiments, a positive eye-closure effect on recall performance was revealed independently of participants' digit and reading span. However, the eye-closure effect emerged only for words participants had denoted as “remembered” (referring to the recollection of a word including contextual details from the study episode), but not for words indicated as “known” (lacking such contextual details) or for words indicated as “guessed”.

To sum up, the eye-closure effect seems to emerge not only for incidentally encoded information but also for intentionally studied items, even though the effect might not be as robust, depending on certain boundary conditions (Parker et al., 2022; see also Kyriakidou et al., 2014, for mixed results with children, and Craik, 2014, for a discussion).

Two accounts have been proposed to explain the beneficial effect of eye closure on memory. In the domain-general account (e.g., Perfect et al., 2008; Wais & Gazzaley, 2014), it is assumed that closing the eyes prevents people from monitoring the environment, thereby reducing cognitive load. The released cognitive resources (e.g., concentration or the central executive) can be used for more elaborate retrieval. It has even been demonstrated that eye closure can reduce the negative effect of auditory distraction on the recall of both visual and auditory details (Perfect et al., 2011), underlining the domain-general effect. 

The modality-specific account, in contrast, proposes that closing the eyes improves visual memory in particular (but not auditory memory) because cognitive resources for visual imagery and simulation are released that stimulate the retrieval of visual information only (e.g., Caruso & Gino, 2011; Wais et al., 2010).

To clarify whether the eye-closure effect is modality-specific or modality-general, Mastroberardino and Vredeveldt (2014) presented children with short video clips showing a theft scene and asked them for details. 

Children who closed their eyes during this inquiry or who looked at a blank screen provided more visual details than children who were exposed to visual distraction by keeping their eyes open. No such effect emerged for the recall of auditory details, suggesting a modality-specific effect. However, retrieval of visual information was also impaired when children were exposed to auditory distraction, which suggests a cross-modal interference. The results thus do not provide clear evidence for either a modality-specific or a modality-general effect of distraction. 

Vredeveldt et al. (2011), however, reported modality-specific effects of (visual or auditory) distraction on adults' recall of visual and auditory information in an eye-witness paradigm. Moreover, the benefits of eye closure seem to be modality-general for less detailed episodic information, but modality-specific for more detailed episodic information (Vredeveldt et al., 2012). Interestingly, this study found no effect of auditory distraction (compared to a quiet context) on visual and auditory information retrieval. 

Thus, the modes of action underlying the eye closure effect on memory are not clear yet, and investigating them in natural settings might be problematic because visual and auditory information is usually not comparable in these settings, including different details (e.g., colors and shapes versus spoken words and sounds). In addition, there might be a confound because auditory information in real-life contexts often includes verbal information, whereas visual information often includes non-verbal information.
Thus, concluding whether closing the eyes benefits memory for visual information only based on real-life events, is difficult. This is true in particular when one seeks to find out whether eye closure can also benefit memory in intentional learning situations (e.g., at school). A better way to examine the modality-specificity would be to use verbal information only that is presented either visually or aurally. Keeping the information content constant can only be achieved in more controlled settings, such as during the learning of word lists or facts that are presented aurally or visually.

To our knowledge, there is only one study (Uchiyama & Mitsudo, 2020) in which participants were presented aurally or visually with lists of unrelated words. After a retention interval, they had to rehearse the words either with open or closed eyes. Then they completed a recognition test, including again aurally or visually presented words, but with keeping their eyes open. 

There was no effect of closing the eyes during rehearsal, neither after 5 min nor after 1 week. However, the eye-closure manipulation preceded the actual memory test and therefore might have yielded no effect. In addition, presentation modality and recognition modality were manipulated between subjects. Potentially, the sample size (N = 110 in Exp. 1 and N = 44 in Exp. 2), and there with the power, was too small to detect an effect.

The present study investigated the eye-closure effect on recall of intentionally learned material, that is, word lists that were presented aurally or visually. If the effect of closing the eyes during a recall —compared to keeping the eyes open—is modality-general, it should emerge for both presentation conditions; if it is modality-specific, it should emerge in the visual presentation condition only (or should be at least larger in this condition compared to the auditory presentation condition).

2 | METHOD

2.1 | Design

A 2 x 2 mixed design was realized, with eye-closure (open vs. closed) manipulated between subjects, and presentation modality of the information to be learned (i.e., visual versus aural) manipulated within subjects. Performance in a recall test (% of previously studied words that were recalled correctly1 ) served as the dependent variable.

2.2 | Sample

The required sample size was calculated using G*Power (Faul et al., 2007) for two one-sided t-tests, assuming a power of 1-β = 0.80, an alpha of 0.025, and a mean effect size of d = 0.5, resulting in N = 128. To be included, participants had to be at least 18 years old, mastering German at a native level, having (corrected) normal visual and auditory abilities, and no diagnosed learning or memory disorders. 

The final sample (N = 129; 26 male, 103 female; mean age: M = 25.0 years, SD = 9.6 years) consisted mainly of psychology students of the local university (64%), 67% of the participants had a high school diploma, and 24% a college or university degree. Participants were recruited via mailing lists of the university, social media, and other channels, and participated with informed consent. They could take part in a lottery to win 10 x 25 EUR; psychology students could also get course credit.

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