José J. Cañas

Research and Innovation

Thinking is the property of the human mind. Scientists engage in constructive thinking: they set up hypotheses and test them, and develop logical chains of arguments to decide which assumptions are facts and which are not. They also create new perspectives for searching out truths by designing more accurate concepts, which allow them to ask new types of questions concerning the states of affairs.

Reading Strategies and Hypertext Comprehension

The literature on assessing the cognitive processes involved in hypertext comprehension during the past 15 years has yielded contradictory results. In this article we explore a possible factor affecting this situation, mainly the fact that previous works did not control for the potential effects on comprehension of reading strategies in hypertext. In Experiment 1, results showed that reading strategies selectively affect the textbase and the situation model level. The number of different nodes read mainly affected the textbase, whereas the reading order influenced the situation model. In Experiment 2, the analysis of reading strategies replicated the effect of knowledge and coherence found in the literature on linear text comprehension (McNamara & Kintsch, 1996), but it was not replicated in hypertext. Low-knowledge participants learned more by following a high coherent reading order, whereas high-knowledge participants learned more by reading the hypertext in a low-coherence order. We discuss the theoretical and methodological consequences of this approach for the study of hypertext comprehension.

Cognitive flexibility and adaptability to environmental changes in dynamic complex problem-solving tasks

People who show good performance in dynamic complex problem-solving tasks can also make errors. Theories of human error fail to fully explain when and why good performers err. Some theories would predict that these errors are to some extent the consequence of the difficulties that people have in adapting to new and unexpected environmental conditions. However, such theories cannot explain why some new conditions lead to error, while others do not. There are also some theories that defend the notion that good performers are more cognitively flexible and better able to adapt to new environmental conditions. However, the fact is that they sometimes make errors when they face those new conditions. This paper describes one experiment and a research methodology designed to test the hypothesis that when people use a problem-solving strategy, their performance is only affected by those conditions which are relevant to that particular strategy. This hypothesis is derived from theories that explain human performance based on the interaction between cognitive mechanisms and environment.

Saccadic velocity as an arousal index in naturalistic tasks.

Experimental evidence indicates that saccadic metrics vary with task difficulty and time-on-task in naturalistic scenarios. We explore historical and recent findings on the correlation of saccadic velocity with task parameters in clinical, military, and everyday situations, and its potential role in ergonomics. We moreover discuss the hypothesis that changes in saccadic velocity indicate variations in sympathetic nervous system activation; that is, variations in arousal.

Microsaccade and drift dynamics reflect mental fatigue.

Our eyes are always in motion. Even during periods of relative fixation we produce so‐called ‘fixational eye movements’, which include microsaccades, drift and tremor. Mental fatigue can modulate saccade dynamics, but its effects on microsaccades and drift are unknown. Here we asked human subjects to perform a prolonged and demanding visual search task (a simplified air traffic control task), with two difficulty levels, under both free‐viewing and fixation conditions. Saccadic and microsaccadic velocity decreased with time‐on‐task whereas drift velocity increased, suggesting that ocular instability increases with mental fatigue. Task difficulty did not influence eye movements despite affecting reaction times, performance errors and subjective complexity ratings. We propose that variations in eye movement dynamics with time‐on‐task are consistent with the activation of the brains sleep centers in correlation with mental fatigue. Covariation of saccadic and microsaccadic parameters moreover supports the hypothesis of a common generator for microsaccades and saccades. We conclude that changes in fixational and saccadic dynamics can indicate mental fatigue due to time‐on‐task, irrespective of task complexity. These findings suggest that fixational eye movement dynamics have the potential to signal the nervous systems activation state.

Do graphical overviews facilitate or hinder comprehension in hypertext

Educational hypertexts usually include graphical overviews, conveying the structure of the text schematically with the aim of fostering comprehension. Despite the claims about their relevance, there is currently no consensus on the impact that hypertext overviews have on the readers comprehension. In the present paper we have explored how hypertext overviews might affect comprehension with regard to (a) the time at which students read the overview and (b) the hypertext difficulty. The results from two eye-tracking studies revealed that reading a graphical overview at the beginning of the hypertext is related to an improvement in the participants comprehension of quite difficult hypertexts, whereas reading an overview at the end of the hypertext is linked to a decrease in the students comprehension of easier hypertexts. These findings are interpreted in light of the Assimilation Theory and the Active Processing model. Finally, the key educational and hypertext design implications of the results are discussed.

Associative strength effects in the lexical decision task

Four experiments explore the role of automatic and attentional processing in producing strength effects in a lexical decision task. Experiment I manipulated the relative proportion of related and unrelated pairs, the stimulus-onset-asynchrony (SOA), and the strength of the prime–target relationship. Results indicated that strength was independent of the proportion of related and unrelated pairs and SOA. Experiment 2 manipulated the relative proportion of strong and weak related pairs and the strength of the prime–target relationship at a relatively long SOA interval (500 msec). Results showed that the strength effect was present when more strong than weak pairs were presented, and it was absent when the stimulus list contained more weak than strong pairs. Experiment 3 replicated the more weak pairs condition of Experiment 2 but with a short SOA interval (100 msec) and showed that the strength effect was found regardless of the large number of weak related pairs presented. Experiment 4 manipulated strength of the prime–target relationship and proportion of strong and weak pairs but introducing a neutral prime condition and a longer SOA interval (1000 msec). Results are discussed within a two-process model (Posner & Snyder, 1975) postulating that the strength effect at short SOAs is due to automatic processes, whereas at long SOAs it is due to the influence of attentional processes.

Are visual programming languages better? The role of imagery in program comprehension

This paper presents one experiment to explain why and under which circumstances visual programming languages would be easier to understand than textual programming languages. Towards this goal we bring together research from psychology of programming and image processing. According to current theories of imagery processing imagery facilitates a quicker access to semantic information. Thus, visual programming languages should allow for quicker construction of a mental representation based on data flow relationships of a program than procedural languages. To test this hypothesis the mental models of C and spreadsheet programmers were assessed in different program comprehension situations. The results showed that spreadsheet programmers developed data flow based mental representations in all situations, while C programmers seemed to access first a control flow and then data flow based mental representations. These results could help to expand theories of mental models from psychology of programming to account for the effect of imagery.

Improving deaf users' accessibility in hypertext information retrieval: are graphical interfaces useful for them?

This paper explores the effect of substituting textual links for graphical ones on the performance of deaf signers in hypertext information retrieval (HIR). Both deaf and hearing users found more targets, were faster and became less disoriented in the verbal hypertext interface than in the graphical one. Deaf users were outperformed by hearing users in all conditions except in short paths with the graphical interface. The results and its applied consequences, which would be also relevant to other users with similar problems than those of deaf signers (elderly people, people with dyslexia, people navigating in a website using a foreign language or people with low literacy) are discussed in relation to the CoLiDeS model of web interaction (Kitajima et al. 2000) and to the overgeneralisation of ‘Picture superiority effect’ (Nelson et al. 1976).

Cognitive inflexibility and the development and use of strategies for solving complex dynamic problems: effects of different types of training

Performance in dynamic complex problem tasks is affected by cognitive inflexibility, whereby people are sometimes unable to adapt their strategies to unexpected changes in their surroundings. This cognitive inflexibility only affects a persons performance when the environmental changes are relevant to the particular problem-solving strategy that they are using. This paper describes a new methodology to detect cognitive flexibility in the use of strategies and presents an experiment designed to test the hypothesis, proving that the type of training affects cognitive flexibility.