Kjell Ohlsson

Understanding small graphical symbols: a cross-cultural study

Graphical symbols such as icons or pictograms as interfaces in modern technological devices have become quite common. Although generally designed in western countries, their use can be found worldwide from audio-visual appliances to computers and computer-related devices. A basic ergonomic principle is to involve the potential users in the design and evaluation stages especially when the user groups are quite diverse. This study was part of an international project on evaluating telecommunication symbols. One of the major objectives was to test different graphical symbols (of the videophone), designed, and tested in Western Europe using subject groups from Asia, Europe, and the United States. This paper would discuss the major portions of the tests involving US and Swedish subjects. Performance indices used were hits, certainties, confusions, and semantic differential ratings. They were useful in analysing how the symbols were recognised, confused, and perceived by different subject groups. They also helped detect differences between groups which otherwise seemed to have similar test results. The results showed differences in patterns of ratings, which may be culturally linked and could help determine aspects of symbol design and usage that may be more helpful in designing instructions, learning aids, etc. Awareness of such subject bias and their implications are important on how one interprets the test results.Relevance to industryThe study outcome can be very helpful for industries in designing and evaluating candidate graphical symbols across various types of consumer products for worldwide use.

Channel capacity and processing of modality specific information

Abstract The synthesis model, designed to explain effects of modality specific information on retention, is presented and tested. The model encompasses qualitative and quantitative components. The qualitative characteristics reflect the physiological properties of the auditory and visual channels. Three parameters are assumed to affect the quantitative efficiency of the channels. Each channel is assumed to have a certain capacity , and processing of information in the channels is determined by situational demands. Furthermore, processing in a channel is regarded as superficial. Increased allocation of processing to the superficial level was manipulated by the use of modality specific distractors and conditions of ‘supracapacity load’. Transformation of information from the visual to the auditory channel was controlled by the use of one mixed-mode and one single-mode experiment. Thirty subjects participated in the mixed-mode experiment and 60 in the single-mode experiment. Both experiments employed an identical distraction task, intervening presentation and free recall of the to-be-remembered items. The results confirmed the predictions of (a) modality specific distraction, (b) supracapacity performance decrement, (c) a larger distraction effect for the auditory channel and (d) transformation effects in the single-mode experiment.

Dynamically deployed support as a potential solution to negative behavioral adaptation

Advanced driver assistance systems are designed to make driving easier that is, to alleviate the drivers workload, and to increase traffic safety. However, traffic safety is affected by negative behavioral adaptation, meaning that drivers tend to increase speed and pay less attention to driving when supported by an advanced assistance system. We relate behavioral adaptation to reinforcement learning at a subconscious level, and propose that driver assistance is dynamically varied within predetermined safety limits. The aim of employing a dynamic assistance policy is to prevent the driver from noticing a constant improvement in vehicle handling. We conclude by describing ongoing work for empirically evaluating an improved lane departure warning system that uses a dynamic assistance policy.

Processing and storage explanations of the modality effect

Abstract A mixed-mode paradigm was used to evaluate two explanations of the modality effect, i.e. the superior short-term retention of auditorily as opposedto visually presented information. The ‘processing notion’ , postulating a larger processing capacity for auditorily presented information gained no support by the present data. The‘storage notion’, postulating a larger storage capacity for a hypothetical auditory as opposed to a hypothetical visual store, was clearly supported by the data. Overall mixed-mode performance and between-modality differences were the measures used in the evaluation proper. The general conclusion of the present study was that the storage notion constitutes a promising beginning towards a broader understanding of the modality effect.

Speed and accuracy in scanning as a function of combinations of text and background colors

An experiment is reported which employed a method of scanning matrices of letters for specific targets. The color of the letters and the color of the background varied. Scanning time was one dependent variable and accuracy in detecting the correct number of targets in each matrix was another. The results showed a relatively close correspondence between scanning time and the rating data of the same color combinations in an earlier study. With respect to accuracy, the present experiment showed that the overall error rate was extremely low.

Fatigue and reading of text on videotext

Three experiments are reported in which the effects of fatigue are studied during the reading of texts presented by means of a videotex system or by means of print on paper. For both these presentations the viewers read texts for a period of 2 h. The reading task was interrupted six times for tests of speed and accuracy in scanning a matrix of letters for given target letters, speed and accuracy in an auditory-motor reaction time task, and a free recall test of the information presented immediately prior to each test session. The three experiments differed with respect to task demands. Experiment I was less demanding than Experiment 2, which in its turn was less demanding than Experiment 3. It was predicted that those viewers who read the texts presented on videotex would show more dramatic effects than the viewers who read texts under more regular print-on-paper conditions. It was also predicted that these effects would be more pronounced for more demanding tasks. The results, however, demonstrated only marginal effects of fatigue. The effects of fatigue were somewhat more pronounced in the videotex group.

Organization by modality, language, and category compared

SummaryAn experiment was presented to test a functionalistic interpretation of the modality effect. This shows a superior recall performance for auditorily as opposed to visually presented verbal information. A total of 60 subjects were presented with mixed-mode (auditory-visual words), mixed-language (Swedish-English words), or mixed-category (category-unrelated words) lists, and were asked to recall the words of each list in any preferred order. The degree of organization according to modality, language, or category and the recall performance were measured. Organization by modality was significantly higher than organization by language or category as predicted by the functionalistic view proposed. The recall performance obtained for auditory and visual words differed in a way predicted by the functionalistic view.

Reading Skill and the Processing of Text Structure.

Abstract Backman, J., Lundberg, I., Nilsson, L.‐G. & Ohlsson, K. 1984. Reading Skill and the Processing of Text Structure. Scandinavian Journal of Educational Research 29, 113‐128. Oral reading speed, free recall and summarization of narrative stories presented on videotex were studied as a function of reading skill, text structure and physical factors such as paragraphing and color cueing of clauses on various levels of importance. A total of 144 subjects (13‐14 years old) participated in the experiment, half of them being rated as poor readers and half as good readers. Good readers outperformed poor readers on all dependent variables. Important propositions were better recalled and were more often included in summaries than less important parts of the texts, especially if they were signalled by a different color. However, the impact of graphical cueing depended on reading skill, text type and task. The interactions were discussed in terms of differences in processing strategies and prior knowledge.

Night-Vision Display Unlit during Uneventful Periods May Improve Traffic Safety

It is always uncertain if a new assistance system enhances traffic safety or not: empirical studies indicate that driving style may deteriorate when the driver experiences the increased safety margin created by an advanced driver assistance system. To minimize this negative effect on driving style, we redesigned a night vision system so that it appeared differently to the driver: we let the systems head-up display be turned off during operation, to be lit up only when the system detected an obstacle (e.g., a pedestrian or animal) on the road ahead. This presentation style was compared in a simulator study to the traditional solution of constantly lit-up display. The results indicate that drivers reacted more reliably (showed less variance in reaction times) using the new system, which implies that the lighting up of the IR-display constituted an effective warning. Also, drivers to a greater extent drove at normal (slower) speeds when using the re-designed system. More generally, systems offering discontinuous support (i.e. only in critical situations) may have less of a negative effect on driving style, as their presence is not felt as vividly by the driver

Continuous versus Situation-Dependent Night Vision Presentation in Automotive Applications

As the number of advanced driver assistance systems in modern cars increases the question of possible negative behavioral adaptation is raised. We have investigated this phenomenon for night vision systems in a driving simulator. One common opinion is that there is a risk for using the enhanced visual conditions that come with these systems to increase speed during nighttime driving and thereby eliminate the safety margins the system was designed to provide. In our study two system approaches were compared, one with continuous presentation and one with presentation only when dangerous objects were detected by the system. The latter approach was meant to minimize the risk of negative adaptation, which was partly confirmed in the study. Moreover, the results showed better and more consistent driver performance with the situation-dependent system and all subjects preferred this approach from a workload perspective.