The Effects of Cognitive Load Theory and Their Implications for the Language-Learning App Duolingo
Abstract
Duolingo is a language-learning application that teaches over 40 languages to 56.5 million active monthly users (David, 2023). This paper explores how the effects of Cognitive Load Theory (Sweller et al., 2018) impact the design of Duolingo’s instructional material and user interface design.
Background
The acquisition of knowledge and skills can be categorized into two distinct types: biologically primary and biologically secondary knowledge (Sweller et al., 2018). Biologically primary knowledge refers to innate abilities and skills that humans have naturally evolved to acquire, such as first language acquisition and social bonding. In contrast, biologically secondary knowledge pertains to culturally significant information, including skills like reading, writing, and learning second languages. While the learning process for biologically primary knowledge is instinctive and unconscious, biologically secondary knowledge requires explicit instruction and conscious effort (Schwieter et al., 2022). This means that, unlike learning a first language, learning a second language is demanding of working memory, and language instruction materials should be optimized to reduce the learners’ cognitive load.
The Effects of Cognitive Load Theory
Cognitive Load Theory (CLT) is a well-regarded educational and psychological framework (Sweller et al., 2018) that investigates how the limited capacity and duration of working memory influence learning and information processing. This paper will explore how the effects of Cognitive Load Theory can be used to optimize the second language learning experience of Duolingo’s 37 million monthly users.
Cognitive Load Theory encompasses two types of cognitive load: Intrinsic and Extraneous cognitive load (Sweller et al., 2018). Intrinsic cognitive load refers to the inherent complexity of information that second language learners must process to become proficient in the second language, while extraneous cognitive load refers to how information is presented to and the activities expected of the second language learners. Teachers of second languages cannot reduce the intrinsic cognitive load of learning a second language but they can reduce the extraneous cognitive load. Several cognitive load effects have been identified (Sweller et al., 2018) and each of these effects has different implications for Duolingo’s instructional material and user interface design.
The Worked Example Effect suggests learners benefit from studying and analyzing worked examples while learning a new skill or concept (Schwieter et al., 2022). Worked examples are instructional materials that demonstrate how to solve a problem or complete a task step-by-step, and are usually accompanied by explanations of the underlying principles and reasoning. This approach to learning reduces cognitive load by eliminating the need for learners to construct solutions from scratch, allowing them to focus more of their limited working memory on understanding the principles and patterns of the problem (Ayres, 2012). Worked examples can also act as a scaffold that guides users through the problem-solving process and can be gradually removed as the learners become more proficient in their second language. Worked examples are common in math textbooks where an example of a solved equation is given to help the learner understand the problem-solving process and apply it to other equations (see Figure 1).
Figure 1 (Joe & Piqosity, 2022)
2. The Split Attention Effect refers to the negative learning outcome that occurs when learners are faced with multiple sources of essential information that require mental integration (Schwieter et al., 2022). Multiple sources of information can include dual-source information, spatially separated content, and redundant information. When the Split Attention Effect occurs, cognitive load becomes high which results in learners retaining less information than if the learning material was presented in an integrated way. For instance, students often encounter instructional materials consisting of diagrams, illustrations, or graphics accompanied by explanatory text that are spatially separated (see Figure 2). As a result, learners must mentally bridge the gap between these disparate elements, imposing a heavier cognitive load on their working memory and consequently impeding their ability to comprehend and retain the material effectively. Studies have shown that students who are presented with effectively integrated information will outperform students presented with disparate information (Chandler & Sweller, 1992).
Figure 2 (Castro-Alonso et al., 2019)
3. The Isolated Elements Effect and the Variability Effect are important aspects of Cognitive Load Theory with relevance to second language learning. The Isolated Elements Effect suggests that learners comprehend and retain information better when language elements, such as vocabulary and grammar, are presented in isolated, manageable units. Breaking down complex language concepts aids in reducing cognitive load and promoting comprehension. Meanwhile, the Variability Effect emphasizes exposing learners to diverse language examples and contexts. By encountering varied language structures and expressions, learners become more adaptable and proficient in real-life language use. Integrating these principles into second language teaching can optimize learning outcomes and enhance learners' ability to understand, communicate, and adapt effectively in different linguistic situations (Schweitzer et al., 2022).
4. The Redundancy Effect arises when learners are presented with extra, unnecessary information alongside essential content. This taxes the learners' cognitive resources and working memory, leading to decreased learning efficiency and comprehension. A common example of the redundancy effect is a teacher teaching to a PowerPoint deck and reading the slides word for word (see Figure 3). The learners have to process both inputs of information simultaneously, taxing working memory and are less likely to retain the information being presented.
Figure 3 (Kuschner & Neelan, 2017)
5. The Transient Information Effect refers to the tendency of newly acquired knowledge to fade or be forgotten over time. When learners are exposed to a large volume of information in a short timeframe it can surpass the brain's capacity to retain and process it effectively resulting in reduced comprehension. This is most oftentimes seen when teaching a novel concept verbally. The learner must store what is being said in working memory to apply it to content later in the lesson. This results in an increased cognitive load and the learner is less likely to retain the information. One study found that students given written instructions far outperformed students given oral instruction (Singh et al., 2012). The students given the written instruction were able to reference the instructions while the students with oral instructions were not able to keep the instructions in their working memory long enough to be useful during the task.
Implications for Duolingo
As we learned above, the effects of the Cognitive Load Theory have direct implications for a language learning app like Duolingo not only in the design of its instructional materials but also in the design of its user interface.
The Worked Example Effect suggests learners benefit from studying and analyzing worked examples while learning a new skill or concept. This concept can be seen at work throughout Duolingo’s instructional materials. Duolingo provides learners with sentence examples that demonstrate the correct usage of new vocabulary and grammar concepts. Duolingo also provides learners with audio recordings of native speakers pronouncing words and sentences which allows learners to hear the correct pronunciation, rhythm, and intonation of the language. By using this worked example, Duolingo enhances the effectiveness of comprehension, retention, and application of the language concepts being taught.
The Split Attention Effect refers to the negative learning outcome that occurs when learners are faced with multiple sources of essential information that require mental integration. Duolingo often presents disjointed information through text-based lessons, audio pronunciations, and sometimes images or diagrams. This disjointed presentation causes learners to have to switch their attention between different parts of the screen which hinders their ability to effectively integrate the information. Duolingo teaches grammar through language tips which are presented on a separate screen from the exercises. Once the user clicks away from the language tip, often an explanation of conjugation or grammar rules, that information disappears and the learner is forced to try to keep that information in working memory to apply it to the exercises. A better design would be to integrate the language tips onto the exercise screens so that users have constant access to the information they need to learn, in effect reducing cognitive load.
The Isolated Elements Effect suggests that learners comprehend and retain information better when language elements, such as vocabulary and grammar, are presented in isolated, manageable units. Duolingo, like many language-learning applications, often presents vocabulary words in lists with translations of images displayed separately. This allows learners to memorize information in manageable chunks. However, while memorizing individual words can be useful, learners might have difficulty remembering them in the context of a conversation or understanding how they fit into sentences. To mitigate this Duolingo could implement conversational practice in addition to vocabulary practice which would allow its learners to practice their vocabulary in real-world settings thereby helping learners use their vocabulary in meaningful ways. The Variability Effect emphasizes exposing learners to diverse language examples and contexts allowing learners to become more adaptable and proficient in real-life language use. Duolingo creates podcasts for their learners to listen to, allowing them to hear the information they have learned in the context of a real-life narrative.
The Redundancy Effect arises when learners are presented with extra, unnecessary information alongside essential content. This taxes the learner's cognitive resources and working memory, leading to decreased learning efficiency and comprehension. An example of redundant information in Duolingo is seen in one of Duolingo’s most common exercises. In these exercises, a sentence in the second language is presented as both written content and spoken content when an avatar on the screen is reading the sentence. This dual presentation of information increases cognitive load because the learner has to synthesize the two streams of information, resulting in a loss of comprehension. To mitigate this effect Duolingo should consider presenting the talking avatar and the written sentences in separate exercises. This will allow the learner to still be listening and reading content in the second language but not have the cognitive load of synthesizing them at the same time.
The Transient Information Effect refers to the tendency of newly acquired knowledge to fade or be forgotten over time. Duolingo mitigates the transient information effect by breaking their lessons down into 5-10 minute lessons that the user can complete in one sitting. Duolingo also encourages its users to practice their language daily. These strategies are known as spaced repetition and deliberate practice which allow users to solidify their language skills over time.
Conclusion
As you can see, the effects of Cognitive Load Theory have significant implications for the design of instructional materials and the user interface of language-learning apps like Duolingo. By being mindful of the effects of Cognitive Load Theory, Duolingo can optimize the learning experience for its users, making language acquisition more effective, efficient, and enjoyable for Duolingo's 37 million monthly users.
Citations
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