Introduction

Olfactory stimulus is gaining increasing attention as a promising learning tool because it can serve as a strong cue for information recall and emotional arousal. The existing literature has identified several benefits of applying olfaction in education, such as attracting students’ attention1, promoting information recall and retrieval2,3,4, invoking emotions5, improving task performance6, and acting as supplementary cues to other sensory information7. For example, in medical education, adding clinically relevant olfactory stimuli can help medical students form episodic memories that are essential for completing tasks efficiently8. In writing exercises, olfactory cues can affect students’ emotions and help stimulate students’ creativity for story writing9. In art education, olfactory stimulus complements the other senses in artistic perception for understanding paintings’ meanings and artistic renderings10.

Particularly, the olfactory channel is directly linked to the limbic system in the brain that processes feelings and emotions11 and can evoke older, more emotional, detailed, and vivid memories12,13,14. For example, Willander and Larsson15,16 found that olfactory cues were potent triggers of autobiographical memory and evoked autobiographical information ontogenetically older than visual, auditory, and verbal information. Chu and Downes17 found that the use of olfactory cues was more helpful in retrieving more details of an initial event and generated a stronger emotional retrieval experience than word label cues.

Despite their beneficial implications for education, olfactory cues have not been widely used in teaching practice. We found several limitations in the current literature, including: (1) most olfactory cues were irrelevant to instructional content, simply contributing to a pleasant ambiance9. (2) Most studies focused on the effects of olfaction on emotion (such as user perception and experience) rather than cognition (such as learning outcomes and cognitive load)18,19,20. (3) The delivery of olfaction lacked precise control and most equipment was too expensive for wide implementation21. (4) Olfaction was rarely used with elementary students who are more sensitive to olfactory stimuli22, their attitude and perceived experience remain unknown. Owing to these challenges, there have been no conclusive empirical findings regarding the effects of olfactory cues on learning outcomes and cognitive load.

To address these research limitations, we conducted an experiment to examine the effectiveness of olfactory cues on retention and schemata construction as learning outcomes, and their effects on learners’ cognitive load and learning experience in poetry learning. Poetry was selected as the learning task in this study due to its capacity to evoke dense imaginative awareness and emotional responses, and thus was more suitable for the use of olfactory cues to promote learning through sensory stimulation, schemata construction, and emotional arousal.

Literature review

Cognition and olfaction

Memory is an important concept in cognition and involves various cognitive processes such as attention, encoding, and retrieval23. Olfactory stimulus, as a unique sensory stimulus, has a significant impact on memory processes. Craik23 in his work emphasized the close connection between attention and memory, and that olfactory cues happen to be powerful tools for attracting attention. Cann and Ross24 proposed that olfactory stimuli were used as context cues in human memory to facilitate the encoding and retrieval of memories. Sorokowska et al.25 explored how a congruent olfactory stimulus context during encoding affected declarative and non-declarative memories, providing further insights into the role of olfactory cues in memory. In addition, olfactory stimuli exhibit unique advantages in memory associations compared to other sensory stimuli14. Specifically, when individuals are exposed to olfactory stimuli associated with past experiences, these olfactory stimuli can rapidly activate the memory networks associated with them, which in turn makes it easier for individuals to match currently presented information with knowledge stored in memory during memory recognition. In the literature, the effects of olfactory stimuli on memory are also often reflected through the process of recognition24,26.

However, olfactory cues are also likely to increase cognitive load, which might lead to cognitive overload for people who have limited ability to receive information across multiple senses at the same time21,27. If not carefully balanced with the main means of communication, olfactory cues with incongruent information can increase cognitive load21. Cognitive load is conceptualized as mental load and mental effort. Mental load refers to the load that is imposed by task demands, while mental effort refers to the amount of cognitive capacity or resources that is allocated to the task demands28. The complexity of learning materials, the correlation between olfactory cues and learning content, and the presentation of olfactory cues may affect cognitive load27,29.

Emotion and olfaction

Olfaction may affect learning by stimulating learners’ emotions. Emotions are crucial to learning and profoundly affect students’ cognition, motivation, and behavior30,31, which can be influenced by olfaction because the olfactory channel is linked to the limbic system of the brain that processes feelings and emotions11. For example, the experimental results of Herz et al.32 show that a mint stimulus could stimulate or activate learners’ emotions and pleasant responses to olfactory stimuli were learned by emotional associations. Ranasinghe et al.33 found that integrating olfactory stimuli such as jasmine, pineapple, mango, and banana could provide learners with richer information and evoke stronger emotional responses such as fear and curiosity than using visual and auditory cues alone. These findings suggest that olfactory stimuli provide a wealth of information that can arouse strong emotions. Emotion arousal is expected to induce enhanced learning experiences and motivation during the learning process21,22,34,35.

Schemata and olfaction

Olfaction can affect the construction of schemata by providing additional information and triggering emotions. Schemata refers to the mental representations of perceived objects and links among them36 and plays a key role in how learners assimilate and accommodate new information. In the context of education, the construction of schemata typically refers to the process of organizing, understanding, and interpreting new information based on existing knowledge and experience during the cognitive process, which is influenced by cognition and emotional states37. Cognition states represent concepts, situations, events, and actions in memory38. New knowledge being added to the original schema formulates a new schema. Emotional states play a direct role in schematic processing. For example, Brown and Taylor37 tested the impact of emotional state on the schematic processing of self-referential material and found that the induction of negative emotions helped participants recall more negative self-referential traits. Due to their capacity to promote memory retrieval and emotional arousal, olfactory cues may play an essential role in schemata construction. However, to the best of our knowledge, there has been no literature examining the impact of olfactory cues on schemata construction.

Review summary and research questions

Our review of current research suggests that olfaction may affect cognition, emotion, and schemata, but the lack of empirical data on the effects of olfaction on learning has hampered the widespread use of olfactory cues in educational practice. Therefore, this study integrated olfactory cues into poetry learning and conducted an experimental study to explore their impacts on learning outcomes, cognitive load, and learning experience. Specifically, we seek to answer two research questions:

  1. 1.

    Can the use of olfactory cues improve students’ retention and schemata construction?

  2. 2.

    What are the effects of olfactory cues on students’ cognitive load and learning experience?

Methods

Ethics statement

The research protocol was performed in accordance with the Declaration of Helsinki, approved by the Institutional Review Board of Central China Normal University (CCNU-IRB-202111046, approved on 2021/11/16), and then reviewed and endorsed by the primary school administrator. The research instruments are safe for students. Written informed consent forms were obtained from both students and their parents one week before the study. All participants were made aware that their participation in the study was voluntary and that their personal identifiable information would remain anonymous at all publications and presentations. Participants can withdraw from the research anytime without penalty.

Participants

The participants were fourth-grade pupils from a primary school in China. A total of 87 students, 43 males and 44 females, participated in the experiment. On average, their age was 9.38 years (SD = 0.49). They had not engaged previously in an experiment that used olfactory media. They came from two parallel classes with similar teaching levels, and each participant was randomly allocated to the experimental group (n = 44, 45.5% female) or control group (n = 43, 55.8% female). There was no significant difference in their performance on the recent Chinese test and the two groups were considered to have the same entry level Chinese learning aptitude (t = 0.175, p = 0.861 > 0.05). No one reported having olfactory-related health problems, such as a cold or anosmia (the physiological incapacity to perceive any olfactory stimulus). To determine the sample size required for Wilcoxon–Mann–Whitney test (two groups), we conducted an a priori power analysis using G*Power version 3.1.9.4. For 80% power (1 − β = 0.80) detecting a Cohen’s d of 0.60, with a significance level of 0.05, a minimum of 74 participants are required for the experiment39. Thus, the sample size of 87 participants was considered sufficient for our experimental study.

Procedure

Before the experiment, we conducted a pilot study with six participants to check the feasibility and accuracy of olfactory cues spread in the classroom and to get feedback from students on their thoughts and experience of text material learning. The participants were asked to learn three poems which were also used in the main experiment. The learning objectives involved recalling, recognizing, and understanding poems. Three participants were presented with three olfactory cues related to the poems in turn while learning the poems and the other three participants learned the poems without olfactory cues. The olfactory cues were later finalized for the main experimental. After studying the poetry, the participants completed questionnaires, tests, and interviews. Since participants said that they perceived the olfactory stimulus and had no other problems, such as olfactory stimulus mixing, it was considered that the procedure could be followed. In addition, the time for students to complete studying the poetry, questionnaires, tests, and interviews was determined to better control the experimental process.

The process of the main experiment is shown in Fig. 1. The experiment was carried out in a well-ventilated environment to avoid olfactory cues mixing. Each participant was assigned a unique user ID to allow anonymous data collection. After being guided to the experimental site, we verbally explained the procedure to the participants and asked if they had any health problems that prevented them from participating in the study (e.g., cold, rhinitis, and anosmia). None reported they did and, thus, after signing the consent form, they were asked to sit in front of the laptop to prepare for the experiment. The experimental group learned the poems on the computer screen, which were programmed to synchronize with olfactory cues using PsychoPy, a program environment widely used in psychology research. The control group only learned poems on screen that matched the experimental group’s learning activities. The olfactory device was adjusted at an appropriate angle to suit the participants’ olfaction.

Figure 1
figure 1

The experimental procedure of this study.

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The researchers initiated the poetry learning process for each participant upon receiving their positive response of readiness. Each participant was given 10 min to complete the learning task, during which the participant could not control the device to change the course of the experiment. They were asked to learn a poem in two minutes, then take a one-minute break before moving on to the next round to make sure the olfactory stimulus had dissipated. Immediately after the learning activity, all the participants were asked to take questionnaires and tests for about 25 min. The only difference between the two groups was the provision of olfactory media. Three days later, the participants completed the delayed test. All the participants completed the questionnaires and tests.

Material

Text materials

This study chose three olfaction-related poems as text learning materials, as shown in Fig. 2. The first poem depicts the beautiful sight of mint blooming in autumn. The second is a poem praising osmanthus flowers. The third poem describes the bleak and tragic scenes of a battlefield. These three poems are similar in length, all of which consisted of four lines with the number of characters ranging from 20 to 28. Despite their different content and topics, the three poems are considered to have comparable difficulty levels and suitable for fourth grades by a Chinese teacher. The three poems are not included in the textbook, and students have not studied them before. We translated the three poems, which can be seen in Table 1.

Figure 2
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The learning materials of this study.

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Table 1 The English version of poems.
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Olfactory cues

This study used three olfactory cues to correspond to each of the poems: mint, osmanthus, and ammonia. Studies have suggested that familiar olfactory stimuli be used for experiments involving the use of olfactory data40. Therefore, before starting the experiment, we surveyed third- and fourth-grade students from two elementary schools based on literature research to understand the commonly familiar olfactory stimuli and students’ attitudes toward integrating olfactory media into learning. A total of 13 olfactory stimuli were investigated and 282 questionnaires were issued. Finally, 273 valid questionnaires were collected and 129 students were interviewed. The survey found that students could identify the smell of common objects in life, such as mint and osmanthus flower.

Olfactory device

Figure 3 shows the olfactory device used in the experiment. The device is self-made by the researchers to deliver olfactory cues during the poetry learning process. It is mainly composed of three devices: a laptop, olfactory components, and a fan.

  • Laptop: The laptop was used to present the poems and control the synchronization of the olfactory device with the poems via a Python-based PsychoPy program. The program displayed poems at predefined time intervals and controlled the synchronised release of olfactory cues during the poem display.

  • Olfactory components: The olfactory cues were stored in liquid form in spray bottles. Three spray bottles containing mint essential oil, osmanthus essential oil, and ammonia diluted with water were used in this experiment. The formula and concentration of olfactory cues were repeatedly tested and adjusted to ensure their relevance to the poem’s content. The specific poetry learning process and the switch-on status of the devices are shown in Table 2. When a poem was presented on the computer, the PsychoPy program immediately controlled the corresponding olfactory spray bottle and fan to switch on, with a delay of 1–2.5 s. The olfactory stimulus sprayed by the spray bottle is transmitted to the students’ nose through the air and the airflow from the fan. When the learning of the poem was complete, the PsychoPy program immediately controlled the corresponding olfactory spray bottle to turn off. The fan continues to work to dissipate the olfactory cues. The distance between the olfactory device and the learners’ nose was about 30–40 cm, and the angle was adjusted between 30° and 45° according to the learners’ height. This approach was adopted because we wanted to create the effect of a natural breeze of scent rather than a suffocating release.

  • Fan: The fan was used to transmit and disperse olfactory cues. During poetry learning, a fan was turned on to transmit olfactory cues to the students’ nose. After the students had learned the poems, the fan was used to ventilate the space so that the olfactory cues disappeared when the next group came in, improving the accuracy of the experiment.

Figure 3
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The olfactory device.

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Table 2 Device usage process.
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Data collection

Test

The test, which consists of an immediate and delayed test, was developed by two experienced teachers in consultation with fourth-grade Chinese teachers. The immediate test contained two types: recognition and schemata. Recognition was the identification of the eight words contained in the three poems from some phrases, including the words in the original poem and some interference words with similar meanings. Schemata is where the students were asked to choose any poem from the three poems and then imagine, draw the scene in the poem, and briefly comment on it. The delayed test contained only one type: recognition.

To examine the schemata formed by participants after studying poetry, we assigned them an assignment to draw visual representations of the poetic scenes envisioned in their minds, along with brief textual explanations. Through a thorough analysis of the participants’ drawings and the elements depicted in them, we were able to gain insights into their mental images, the connections they established, and any discrepancies in their comprehension. This analysis allowed us to evaluate the structure, complexity, and accuracy of the schemata constructed by the participants. The criteria for assessing the schemata comprised four dimensions: memory, comprehension, emotion, and imagery. The score of each dimension is 0–3, as shown in Table 3. Memory mainly examines how many elements students draw in the poem; comprehension tests how well students grasp the meaning of the poem; emotion concerns whether students understand the emotion expressed in the poem; imagery mainly focuses on the consistency of the picture presentation and the artistic conception of the poem. The internal consistency of the four dimensions is considered high (Cronbach’s α = 0.913).

Table 3 Evaluation dimensions of schemata.
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The students’ performances in the schemata question were scored by four graduate students. They were divided into two groups and scored separately after receiving one-day extensive training by a domain expert who supervised the process. Consistencies between raters were typically calculated using Spearman correlations (0.95) and the dimensions were memory (0.913), understanding (0.831), emotion (0.728), and image (0.757). There was a strong consistency among the raters, so the mean of the scores of the two groups was taken as the final score of the schemata question.

Questionnaire

A 5-point Likert scale questionnaire was employed to obtain feedback from the participants about the olfactory application and related olfactory stimuli and poetry learning: 1 (strongly disagree), 2 (disagree), 3 (neutral), 4 (agree), 5 (strongly agree). This questionnaire was divided into two sections: cognitive load and learning experience (Supplementary Information).

Cognitive load

The cognitive load questionnaire was modified from the measure developed by Hwang et al.41 to adapt to this learning activity. It consists of eight items and includes five items for mental load and three for mental effort. The Cronbach’s alpha values of the two dimensions are 0.86 and 0.84, respectively. Example items are: “I did not have enough time to answer the questions in this learning activity” and “This way of learning poetry was difficult to understand.”

Learning experience

The learning experience questionnaire was developed based on the measures of Ademoye and Ghinea42 and Covaci et al.11. Six questions were used to evaluate learners’ experiences and feelings of learning activities. The first three questions were mainly used to investigate the students’ experiences of the whole learning activity. The Cronbach’s alpha value was 0.83. Example item is: “This learning activity was fun.” The last three questions were used to evaluate the correlation between olfactory cues and poetry. The Cronbach’s alpha value was 0.87.

Data analysis

In this study, the non-parametric test of Mann–Whitney U was selected to assess the between group differences regarding two poem learning tasks and questionnaires. Because all data were not normally distributed as indicated by the Shapiro–Wilk’s test results (p < 0.05), and the data type for the questionnaire and schemata ratings was ordinal rather than continuous. Moreover, low correlations in participants’ recognition scores among the three poems and other variables (i.e., schemata score, cognitive load, and learning experience) were reported (as seen in Supplementary Information, plenty of correlation coefficients are less than 0.3). Statistical significance was considered when the calculated probability (p) was smaller than 5% (p < 0.05). IBM SPSS version 26 was used for all statistical analyses.

Results

Poetry learning performance

Recognition

As shown in Table 4, in the comprehensive recognition performance on the immediate test, the results showed no significant difference between the experimental group and the control group, p > 0.05. Similarly, the results showed no significant difference was found between the two groups in the learning of the first poem (p > 0.05), second poem (p > 0.05), and third poem (p > 0.05). In the delayed test, the experimental group had better comprehensive recognition performance than the control group, p < 0.05, d = 0.46. Similarly, the experimental group also outperformed the control group in the second poem, p < 0.05, d = 0.56. However, there was no significant difference between the two groups in the first poem (p > 0.05) and third poem (p > 0.05).

Table 4 Results of participants’ performance in terms of recognition on the immediate and delayed test.
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Schemata

As shown in Table 5, the results indicated that the difference in the comprehensive schemata performance was significant (p < 0.05, d = 0.56) between the two groups. The value for the experimental group was higher than that for the control group, revealing that the learners performed higher in comprehensive schemata when they used olfactory media synchronized with traditional digital media to learn poetry. Moreover, in the comprehension (p < 0.01, d = 0.56), emotion (p < 0.05, d = 0.56), and imagery dimensions (p < 0.05, d = 0.48), the experimental group outperformed the control group. However, no significant difference was found in the memory dimension between the experimental group and control group, p > 0.05.

Table 5 Results of participants’ performance in terms of schemata.
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Figure 4a shows the works of three participants in the experimental group, and Fig. 4b shows the works of three participants in the control group. It can be seen that the experimental group performed better than the control group, especially in the dimensions of comprehension, emotion, and imagery. Taking the third poem as an example, the participants in both groups basically drew the elements of the poem (bones, a field, and people), but the experimental group participant portrayed a more vivid image, better comprehension of the meaning of the poem, and stronger bleak feelings.

Figure 4
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Examples of the participants’ schema works. (a) Excellent schema works of the experimental group; (b) Poor schema works of the control group.

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Analysis of cognitive load

The experimental group students needed to deal with the information of visual and olfactory senses at the same time; this burden may be beyond their ability to manage, so it is necessary to know the cognitive load of students in the learning process. The results from the Mann–Whitney U test showed that there was no significant difference between the cognitive load ratings of the two groups (p = 0.194 > 0.05), indicating that adding olfactory cues in the learning process of text materials did not cause additional cognitive load for students. Similarly, there were no significant differences between the two groups in two aspects of cognitive load: mental load (p = 0.205 > 0.05) and mental effort (p = 0.496 > 0.05).

Analysis of learning experience

As shown in Table 6, the results showed that there was no significant difference in learning experience between the two groups (p > 0.05). However, the experimental group scored significantly higher on Q1 (p < 0.05, d = 0.28) and Q2 (p < 0.05, d = 0.33) than the control group. This suggests that adding olfactory cues to the learning process of text materials is more interesting and enjoyable.

Table 6 Results of participants’ learning experience.
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Discussion

This study investigated the effects of adding olfactory cues to text materials learning on students’ learning outcomes, cognitive load, and learning experience. The results support the effectiveness of olfactory cues for enhancing delayed retention and schemata construction, and inducing positive user experience during the poetry learning process. However, olfactory cues have a limited impact on cognitive load.

Can the use of olfactory cues improve students’ retention and schemata construction?

The study results show that the use of olfactory cues improved students’ retention and schemata construction. Regarding retention, accompanying text materials with olfactory cues increases the delayed test scores rather than the immediate test scores. In the existing literature, researchers have mainly investigated the effect of olfactory cues on immediate retention6,11,42,43. Our findings were consistent with those of Covaci et al.11 and Ademoye and Ghinea42, indicating that olfactory cues had no significant effect on participants’ immediate performance. Compared to immediate retention, delayed retention has rarely been investigated in the literature. We found only one olfactory-related study that conducted a delayed test3, of which the results are consistent with our findings, showing that olfactory cues are more effective at enhancing memory in a delayed test two weeks later. Compared with other sensory stimuli, olfaction is our most primal sense, and it links directly to the part of our brains that controls memory and emotion11. Moreover, when completing recognition tasks, the olfactory cues in the experimental condition can assist participants to construct associations between the selected words and poem schemata44. Therefore, olfactory cues can stimulate episodic memory by evoking emotion8 to better retrieve long-term memories and promote delayed retention.

Additionally, it is important to note that the difference in delayed recognition performance was primarily due to the performance in one task (Poem 2), of which the olfactory stimulus was most closely related with the poem content, suggesting a potential moderating effect of olfaction relevance. Olfactory cues related to learning content follow the principle of cross-modal correspondence and semantic congruency between different sensory dimensions, which can induce attention and support the understanding and retention of information through the accommodation of learners’ sensorimotor skills45,46. For example, in the study by Seigneuric et al.47, participants were exposed to an olfactory stimulus (e.g., the smell of an orange) while they were asked to explore a picture containing a corresponding visual cue (e.g., the image of an orange) embedded among other objects. The results showed that the visual cue related to the olfactory stimulus was explored more quickly and for less time when the olfactory stimulus was consistent. Similar results were found in information recall tasks or word search games when cue-related stimuli were emitted42,43.

Regarding schemata construction, olfactory cues were found to have a positive impact as measured by participants’ schemata scores. The literature provides theoretical explanations for this phenomenon. Paivio48 argues that sensory cues with high imagery values activate concrete meanings of abstract associations and thus enhance retention. In our study, olfactory cues concretized the memory traces in text materials and, in turn, contributed to the reconstruction of completed memory episodes. In addition, we found insignificant differences in the memory dimension of schemata rating. We speculate that although the participants in the experimental condition have memorized more episodic details through olfactory cues, they were unable to draw them due to a lack of ability or time. Our speculation was supported by De Bruijn and Bender12 who made similar observations.

What are the effects of olfactory cues on students’ cognitive load and learning experience?

The study results show that the addition of olfactory cues to text materials learning did not cause additional cognitive load. This indicates that olfaction is coordinated with the main perception mode and there is good compatibility between the senses. This finding is consistent with Washburn et al.49 who pointed out that using olfaction in virtual reality is an effective way to support training and learning without compromising the user’s cognitive load. This finding can be verified from two aspects of cognitive load: mental load and mental effort. Mental load is related to the complexity of learning materials while mental effort is related to learning strategies50. Whereas previous studies on cognitive load were limited to audio-visual channels, this study investigated olfactory cues which are processed in a different channel. This channel is named the olfactory channel and is parallel to audio-visual channels11,45. Consequently, olfactory cues are different from traditional text materials, which are processed in a different channel. Thus, their addition to the learning materials is less likely to increase mental load. Regarding mental effort, since olfactory stimuli are perceived intuitively, they automatically activate emotions and construct associations44. As a result, the participants did not need to use additional strategies for information processing and their mental effort was not increased. Therefore, it is reasonable to find that since the mental load and mental effort of the students did not increase, there was no increase in cognitive load.

Our study confirms that the presence of olfactory cues in the process of learning text materials enhances the participants’ learning experience, especially the level of enjoyment and fun. These results are consistent with the findings of previous studies11,51. A possible reason is that rich media content enhances the way humans interact with learning materials and environments51, and participants find it a novel experience to integrate new media into the learning process11. According to Clark52, this phenomenon is called the novelty effect, which may be present in our study intervention with olfactory cues. It is important to note that the novelty effect may fade over time as students become more customized to this learning media53.

Implications

Our study results have important implications for the use of olfactory cues in education. First, we suggest the selective inclusion of olfactory cues in subject teaching to assist students to better employ and integrate their different sensory channels and improve their performance. Olfactory cues have been proven to promote delayed retention and schemata construction without increasing cognitive load, especially in situations that require rote memorization of a standardized set of information such as language, art, and history43.

Second, olfactory cues should be carefully designed and precisely controlled to afford learners with enhanced learning experience and schemata construction. This mainly includes the selection of olfactory stimuli features (e.g., pleasure, content relevance) and the control of the delivery parameters (e.g., intensity, storage, generation, duration, removal, timing). For example, the relevance of olfactory stimuli with learning content may affect the retention of information. Moreover, future research is needed to explore advanced olfactory technology that can be customized and applied at scale to create high-fidelity simulations that improve learning.

Third, olfactory cues are not omnipotent. Their impact on performance is more effective after a time delay but does not necessarily lead to better immediate performance and learning experience. Therefore, teachers need to make reasonable choices according to the current instructional objectives. Moreover, researchers should further investigate how olfactory cues can be designed to bring about better learning outcomes and experiences and explore how olfactory cues can be integrated with various environments (e.g., traditional environment, VR environment, AR environment, metaverse, etc.).

Limitations and future research

We acknowledge that our study has some limitations that need to be explored further. First, despite our best efforts to control the presentation of olfactory cues by computer, the device used to present olfactory cues was self-made, which may have led to problems such as insufficiently precise concentration, delayed timing control (release, duration, and removal), and mixing of olfactory stimuli. We suggest that future research replicates our findings using more standardized and readily available devices, such as commercial scent diffusers. Second, the study results are limited to the context of text materials learning. Future researchers can extend the research scope to include more media forms. Third, this study relied solely on quantitative data to examine the impact of olfactory cues without an in-depth analysis of directly observed olfactory learning experiences (e.g., behavior, attitude, emotion, etc.). Future research should incorporate qualitative evidence to achieve data triangulation and interpretability. Additionally, self-assessment results of olfactory function may be unreliable. We recommend conducting an actual olfactory test prior to such an experiment to ensure more accurate measurements of individual olfactory abilities and to control for the variance in olfactory sensitivity among participants. Lastly, we recommend that future research investigates the influence factors of olfactory learning, such as gender, age, social and cultural factors, experience, and preference.