Effects of Cognitive Load on Processing and Performance. Amy B. Adcock. The University of Memphis

Transcription

1 Effects of Cognitive Load 1 Running Head: Effects of Cognitive Load Effects of Cognitive Load on Processing and Performance Amy B. Adcock The University of Memphis

2 Effects of Cognitive Load 2 Effects of Cognitive Load on Processing and Performance Cognitive load is generally defined as the amount of mental resources necessary for information processing. High cognitive load requires the user to expend extra memory resources in order to deal with incoming information. It is speculated that the necessity for extra resources can cause a deficit in processing efficiency and social performance. Several empirical studies link cognitive load effects to the components of working memory by examining the effects of presentation modality on working memory load (Goolkasian 2000; Mayer & Moreno 1998; Mayer, Moreno, Boire & Vagge 1999; Mousavi, Low & Sweller 1995). Other tests of cognitive load theory focus on the modality of information presentation and effects of split attention without relating these effects to the components of working memory (David & Hirshman 1998; Kalyuga, Chandler & Sweller 1997; Velayo & Quirk; Yeung 1999). Empirical tests have also investigated the role of cognitive load on types of performance (Katsikopoulos, Duse-Anthony, Fisher & Duffy 2000; Lewis & Linder 1997; Pontari & Schlenker 2000). The purpose of this paper is to examine research studying the effects of cognitive load with an emphasis on the relationship between cognitive load and processing of information. Cognitive Load and Working Memory The term working memory refers to a brain system that provides temporary storage and manipulation of the information necessary for such complex cognitive tasks such as language comprehension, learning and reasoning (Baddley, 1992). In Baddley s (1992) theory of working memory, he divides the memory system into three separate components. The central executive component controls attention and oversees two slave components. The phonological loop is responsible for processing speech-based information such as spoken language. The visuospatial sketchpad processes visually depicted information such as

3 Effects of Cognitive Load 3 diagrams. Because, according to the theory, these two slave components act independently of one another, presentation of simultaneous information tailored to each component may be beneficial for effective processing of information. It has been hypothesized that cognitive load issues may be related to the components of working memory. Several researchers have examined effects of cognitive load on information retention based on this architecture of working memory (Goolkasian, 2000; Mayer & Moreno, 1998; Mayer, Moreno, Boire & Vagge 1999; Mousavi, et al., 1995). These studies have sought to support the idea that information processing can occur in both slave components of working memory at the same time. Research on capacities of working memory components test for effects when subjects are given concurrent input in different modalities. Several of these studies have also seen evidence of a split attention effect, which occurs when subjects must divide attention between separate tasks and mentally integrate sources of information. It is thought that this process of integration increases cognitive load thereby decreasing performance and that this effect could also be alleviated by dual modality presentations. Researchers interested in examining the effect of presentation modality and split attention have performed studies investigating how information processing is impacted by the amount of cognitive load on working memory components. Mousavi, et al. (1995) investigated the presentation modality effect by comparing retention of subjects presented with information constructed using two different modalities (e.g. visual-auditory) to those presented with information using the same modality (e.g. visual-visual). They speculated that a dual modality presentation would decrease cognitive load and therefore increase working memory capacity. This increase in capacity should manifest in better retention of the materials. Although they did

4 Effects of Cognitive Load 4 not directly measure cognitive load in this study, some interesting findings support existing cognitive load theory. In six different experiments subjects were presented with instructional information in geometry. Each condition differed by modality of information regarding a geometry problem and associated diagram. Some were presented with a visual diagram and text explanation, others were allowed to hear a narrative explanation and look at a visual diagram. Retention of material was quantified by a testing phase consisting of two sets of similar problems. Their findings indicated that subjects performed better when presented with a dual modality, i.e. visual diagram and auditory explanations. They deduced that this dual presentation did decrease the cognitive load on working memory so that the subjects were able to process both formats at the same time. More specifically they stated, because both systems can be used simultaneously, limited working memory capacity might be effectively increased if information [that must be processed] is presented in a manner that permits it to be divided between the two systems rather than processed in one system alone (Mousavi, et al. 1995, p 331). In this same study, researchers also looked at effects of split attention in terms of the architecture of working memory (Mousavi, et al. 1995). Their interest here is to further support the evidence that working memory components have the ability to simultaneously process different modalities. The split attention effect is seen when subjects must divide their attention and mentally integrate sources of information. If working memory components allow us to process visual and auditory information at the same time then the necessity to mentally integrate the two different modalities should disappear. This increase in capacity to focus on and process information is the result of a lowered cognitive load.

5 Effects of Cognitive Load 5 Conditions varied in terms of how much time was allowed for subjects to study the material and the presentation modalities. These modalities were identical to those described above. The hypothesis for this part of the study is that the increase in working memory capacity allowed through dual presentations modes will make integration of information easier by reducing cognitive load. Quantifying the time taken in solving the problems was used as evidence. Findings from the research did indicate that when subjects were required to mentally integrate sources of information, due to identical presentation modalities, working memory resources were unavailable and processing time of the material suffered. Mayer and Moreno (1998) tested theories of cognitive load and working memory in terms of a split attention effect. They believe the split attention effect is caused by subjects being required to integrate and process multiple sources of information. They were interested in testing a dual presentation mode of instructional materials to see if components of working memory were processed separately. They felt if visual and auditory components were presented simultaneously, no split attention is necessary. Because they are being processed in two different places there is no need to mentally integrate the information. Therefore, a lower cognitive load would result and retention would be higher. Their study presented subjects with a multimedia explanation of the causes of lightning. In one condition, subjects viewed a visual diagram and text based explanation. The other condition viewed the diagram and heard the explanation as a narrative. Retention tests showed the subjects in the diagram-narrative condition outperformed those in the diagram-text condition. The authors concluded that when different sources of material are presented in the same modalities, working memory is overloaded and deep processing cannot occur. If information is presented in different modalities, subjects had more

6 Effects of Cognitive Load 6 room in their cognitive systems to hold the information. Also, because modalities are different, mental integration is not necessary and cognitive load is reduced even more. In a later paper, Mayer et al (1999) expanded on the concept of working memory load and examined how multimedia environments can be used to help people integrate verbal and visual information. Subjects were shown a multimedia instructional unit on auto mechanics. Conditions varied by order of presentation and narration. Some were presented with concurrent animation and narration, and some subjects received small or large bites of narration and then animation. Subjects were tested for retention by several methods. Findings indicated that groups presented with verbal and visual information concurrently outperformed the other conditions. They concluded that learners were more able to build referential connections between corresponding visual and verbal representations when both are held in working memory simultaneously (p 643). Other researchers have examined the split attention effect on components of working memory and cognitive load. Goolkasian (2000) tested the how presentation format affects reasoning capabilities. Her rationale for the study states that attendance to multiple sources of information causes a split attention effect, which interferes with reasoning capacity. When material is presented in formats that are easily integrated, the load on working memory is reduced resulting in more efficient processing. She hypothesizes that participants will show best reaction times and lower error rates with pictorial material. Her experiments consisted of showing subjects representations of concepts in different formats, pictorial, textual or auditory. In some cases, formats were combined. After being shown stimuli, participants were shown background information about the objects. They were then asked a verification question about the presented material. Reaction times and error rates were

7 Effects of Cognitive Load 7 measured for all participants. In general, pictorial representations fared best in terms of reaction times and error rates. However, the experimenter did see an unexpected format effect in the last two experiments. Reaction times during problem solving were faster when participants were required to integrate information over formats. She proposes these results could be due to a reduction in cognitive load and an increase in working memory capacity and when integration across formats is required. An examination of the previous studies shows a potential relationship between theories of cognitive load and components of working memory. Each of the tests performed attempted to draw a link between the defined components of working memory and the effects of information presentation on their capabilities. It may make sense to relate the findings of these studies to the limited capacities of the working memory system. These limitations, it appears, can be remedied by carefully presenting information in a manner that does not overload one s working memory components through a singular format. Some researchers have studied the effects of split attention and presentation modality without necessarily drawing links to Baddley s working memory theory. This paper will now examine the results of these studies. More Research on Cognitive Load The purpose here is to briefly review literature addressing recall performance and cognitive load that does not directly refer to Baddley s theory of working memory. Although it is not directly referenced, an examination of these studies could be interpreted as being compatible with the studies reviewed previously. These researchers were primarily interested in testing instructional formats to see if presentation modality and split attention had any effect on retention processes.

8 Effects of Cognitive Load 8 Presentation Modality Effect. Velayo and Quirk (2000) performed an experiment that attempted to determine how modality influenced recall on a paired-associate learning task. They were interested in supporting previous research showing improved recall and retention from audiovisual presentations. Subjects either observed concept pairs through pictorial, textual or auditory representations or were presented with mixed modalities. They were then tested for recall of the concept pairs. Findings indicated that subjects receiving visual-auditory information outperformed other mixed modalities. Although these results match those found in previously discussed studies, these authors do not discuss the concept of working memory components as a justification for their results. Instead, they relate problems associated with cognitive load and presentation modality to difficulties in encoding. They concluded that the difficulties in encoding information in similar modalities imposed a high cognitive load on subjects and had a negative effect on recall. Split Attention Effect and Levels of Expertise. Other studies have examined the role of cognitive load management and effects of split attention and expertise in the subject area. Again, split attention is defined as the process of mental integration of elements in order to make sense of presented information. This mental integration is responsible for a large amount of cognitive load and empirical testing seeks to reduce its effect on the cognitive system (Kalyuga, Chandler & Sweller 1997; Yeung 1999). Yeung examined the effects of cognitive load by presenting subjects with two vocabulary formats, a separated but integrated glossary. The purpose of the study was to see if the process of attending to two distinct sources of information might impose a high cognitive load through the split attention effect. Subjects at varying levels of expertise were presented with vocabulary definitions. In one experiment, he attempted to measure cognitive

9 Effects of Cognitive Load 9 load by self-perception of the subjects. This is the only mention of direct measures of cognitive load in all of the reviewed studies. Findings indicated interesting aspects of the split attention effect. For subjects with a low amount of expertise, an integrated format that reduced the split attention effect proved more effective for comprehension. High-level knowledge subjects performed better with a format of separated terms. He speculates that the integrated format reduces cognitive load by eliminating the need to search for meaning resulting in increased comprehension but the presence of the meanings within the text increases redundancy. This redundancy effect has a negative impact on retention of subjects with some measure of expertise in the subject area. Kalyuga, Chandler and Sweller (1997) also found that levels of expertise affect the impact of cognitive load. The research tested whether the integration of text and diagrams imposed a higher cognitive load negatively impacting retention. They wanted to examine whether multiple elements of information would impose a higher cognitive load on subjects. They felt that if a person is familiar with material, expressions are processed as single elements. Therefore, multiple elements should not impose a high cognitive load on expert users. They tested their hypotheses by testing physically integrated information against information that must be mentally integrated by the subject. Findings indicated that the integrated diagram and text group outperformed the other groups. They also found that the diagram and text group outperformed the text only group. They concluded that this integrated format is effective for low level subjects but they did see a negative redundancy effect for high-level learners. They suggest that this redundancy effect may impose a higher cognitive load on subjects with a high level of expertise and negatively impact their learning.

10 Effects of Cognitive Load 10 So far, the previously reviewed empirical studies have examined effects of cognitive load on retention of materials. This is partially due to the fact that most of the research is centered in the field of information processing. They all seem to indicate that a high cognitive load whether caused by differing presentation modalities or by split attention effect has a negative impact on retention of materials. Researchers have attempted to find ways of presenting information that reduces the need for users to expend mental resources by presenting complementary modalities and by eliminating the need to mentally integrate sources of information. One other interesting line of research in this area has looked at cognitive load and social performance. The focus of this paper will now turn to empirical studies examining the effects of cognitive load on selfpresentation and performance. Cognitive Load and Other Types of Performance Several studies have looked at the role of cognitive load in performance effectiveness (Katsikopoulos, et al. 2000; Lewis & Linder 1997; Pontari & Schlenker 2000). The general consensus in this field of research is that increased cognitive load hampers performance. The research that will be discussed in this paper manipulated cognitive load when doing different tasks to see its effects of different types of performance. Lewis and Linder (1997) sought to account for the effect of pressure on task performance. The provision of a distraction is counted as the mechanism for adding cognitive into the performance system by diverting attentional processes from the task. Subjects were asked to putt a golf ball toward a target point. To add a cognitive load, subjects were given a distraction task of counting backward from 100 by twos in an audible voice. Findings indicated that the distraction task was sufficient to decrease performance significantly. However, when pressure to perform was increased, performance was not significantly different from the

11 Effects of Cognitive Load 11 nondistracted condition. The authors explain this by stating if this pressure is consistent throughout the mastery of the task, the attentional processes required during performance are decreased and an increase of cognitive load will have no effect. They also feel that it would be interesting to replicate this experiment with highly trained performers to see the resulting effect. Pontari and Schlenker (2000) constructed empirical tests for cognitive load and selfperformance. They believe that previous research often starts with the idea that limited cognitive resources make it more difficult for people to perform more than one cognitively effortful task at once (p 1093). Experimenters asked subjects to role-play during an interview scenario. They were not informed of their role type until after the experiment. Cognitive load was manipulated by asking the participants in the experimental condition to recite a rehearsed eight-digit number during the interview process. Later they were assessed on recall of the number and a comparison of their self-beliefs with the role they played. Their findings indicated that self-presentation activities could span from mindless and automatic to those requiring high cognitive resources. Subjects that defined themselves as introverted seemed to need the highest amount of cognitive resources for self-performance. Their manipulations of cognitive load impaired performance but only for introverted subjects playing extroverted cognitive roles. Decidedly, the task of changing roles from an introvert to an extrovert is a demanding one. Specifically they state, in a social vacuum, cognitive busyness logically leads to inferior performance on demanding tasks that require cognitive control (Pontari & Schlenker 2000, p 1106). Another study in the field of cognitive load looked at how participants alter decisionmaking during driving. It was hoped this study would add to the field of traveler information. Subjects were tested using a driving simulator, baseline data on route choice was provided by a

12 Effects of Cognitive Load 12 previous experiment. They speculated that drivers would have to eliminate at least one of the route attributes (range of alternative route, time of travel) needed for decision making with an increase in cognitive load. It is thought this would simplify the process of deciding on a travel route to account for resources used to deal with the increased cognitive load. The findings from their study supported their speculations showing that drivers consciously decreased their task expectations when given a higher cognitive load. The authors here do state limitations to this study such as methodology. Overall though, it seems that the results support previous findings about the effects of cognitive load on processes. Conclusion The research studies examined here were fairly consistent in their definitions of what cognitive load is and how it affects human processing and performance. They all state the resources available in human memory and how it can alter cognitive processes can define cognitive load. In these studies, cognitive load was studied as a result of the effects it manifests. There is also strong evidence presented linking effects of inducing cognitive load with Baddley s theory of working memory. Studies of presentation modality show how information presented in a way that incorporates coding for individual modalities are effective at reducing cognitive load and increasing retention. Research examining the split attention effect also provides support of the capacities of working memory and attentional resources. Studies showed that split attention effects had the tended to increase cognitive load and decrease performance. Finally, the effect of cognitive load on different types of performance was examined. In terms of task performance, it appeared that high cognitive load had a negative effect unless the task was rehearsed to proficiency. In social performance, high cognitive load also had a negative effect when subjects found the method cognitively taxing. The final study, examining decisions

13 Effects of Cognitive Load 13 during driving also evidenced that subjects will decrease their cognitive task when imposed with a higher cognitive load. A review of these studies seems to provide a good amount of evidence for the limitations of the cognitive system. When a high amount of cognitive resources are necessary for a task, it is harder to perform. It appears that one method of reducing this need for resources is to present information tailored to each individual component of working memory. Also, the presentation of information so that it does not have to be mentally integrated can be beneficial. Another interesting point found in this research is that task proficiency and levels of expertise seem to reduce the effects of cognitive load. Finally, it seems to be that none of these studies have found an effective way to actually measure cognitive load itself. Perhaps this indicates a fault in all of these studies and a potential for research in the future.

14 Effects of Cognitive Load 14 References Baddley, A. (1992). Working memory. Science, 255, David, P., & Hirshman, E. (1998). Dual-mode presentation and its effect on implicit and explicit memory. American Journal of Psychology, 111(1), Goolkasian, P. (2000). Pictures, words, and sounds: From which format are we best Able to Reason? The Journal of General Psychology, 127(4), Kalyuga, S., Chandler, P., & Sweller, J. (1997). Levels of expertise and user-adapted formats of instructional presentations: A cognitive load approach. Paper presented at User Modeling: Proceedings of the Sixth International Conference, UM97, Vienna, New York. Mayer, R., & Moreno, R. (1998). A Split-Attention Effect in Multimedia Learning: Evidence for Dual Processing Systems in Working Memory. Journal of Educational Psychology, 90(2), Mayer, R., Moreno, R., Borrie, M. & Vagge, S. (1999). Maximizing Constructivist Learning From Multimedia Communications by Minimizing Cognitive Load. Journal of Educational Psychology, 91(4), Mousavi, S. Y., Low, R., & Sweller, J. (1995). Reducing Cognitive Load by Mixing Auditory and Visual Presentation Modes. Journal of Educational Psychology, 87(2), Pontari, B. A., & Schlenker, B.R. (2000). The Influence of Cognitive Load on Self-Presentation: Can Cognitive Busyness Help as well as Harm Social Performance? Journal of Personality and Social Psychology, 78(6), Velayo, R. S., & Quirk, C. (2000). How do Presentation Modality and Strategy Use Influence Memory for Paired Concepts? Journal of Instructional Psychology, 27(6), Yeung, A. (1999). Cognitive Load and Learner Expertise: Split-Attention and Redundancy

15 Effects of Cognitive Load 15 Effects in Reading Comprehension Tasks with Vocabulary Definitions. The Journal of Experimental Education, 67(3),