Design protocol data analysis methods form a well-known set of techniques used by design researchers to further understand the conceptual design process. Verbal protocols are a popular technique used to analyze design activities. However, verbal protocols are known to have some limitations. A recurring problem in design protocol analysis is to segment and code protocol data into logical and semantic units. This is usually a manual step and little work has been done on fully automated segmentation techniques. Physiological signals such as electroencephalograms (EEG) can provide assistance in solving this problem. Such problems are typical inverse problems that occur in the line of research. A thought process needs to be reconstructed from its output, an EEG signal. We propose an EEG-based method for design protocol coding and segmentation. We provide experimental validation of our methods and compare manual segmentation by domain experts to algorithmic segmentation using EEG. The best performing automated segmentation method (when manual segmentation is the baseline) is found to have an average deviation from manual segmentations of 2 s. Furthermore, EEG-based segmentation can identify cognitive structures that simple observation of design protocols cannot. EEG-based segmentation does not replace complex domain expert segmentation but rather complements it. Techniques such as verbal protocols are known to fail in some circumstances. EEG-based segmentation has the added feature that it is fully automated and can be readily integrated in engineering systems and subsystems. It is effectively a window into the mind.

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This paper proposes a task-related electroencephalogram research framework (tEEG framework) to guide scholars’ research on EEG-based cognitive and affective studies in the context of design. The proposed tEEG framework aims to investigate design activities with loosely controlled experiments and decompose a complex design process into multiple primitive cognitive activities, corresponding to which different research hypotheses on basic design activities can be effectively formulated and tested. Thereafter, existing EEG techniques and methods can be applied to analyse EEG signals related to design. Three application examples are presented at the end of this paper to demonstrate how the proposed framework can be applied to analyse design activities. The tEEG framework is presented to guide EEG-based cognitive and affective studies in the context of design. Existing methods and models are summarized, for the effective application of the tEEG framework, from the current literature spread in a wide spectrum of resources and fields.

Direct interfacing of computers with the human brain is one of the holy grails of computer science and has been in the computing folklore since the very beginning of computing history. The challenges researchers are facing are non-trivial and the breakthroughs are non-negligeable. Measuring the hardness of a mental task is a fundamental problem in design sciences. In this context, the relationship between electroencephalograms (EEG) signals and the design process is an area of research with applications to the understanding of the creative process and next generation CAD/E systems. Such systems are aiming at becoming more collaborative, conceptual, creative and cognitive. We posit that the relationship between EEG signals, cognitive states and the perceived hardness of design problems is non-trivial. Different problems typically have different levels of perceived hardness. To test this, we study the use of microstate analysis to the segmentation of videos of subjects submitted to creative tasks of various difficulty. Problems and subtasks of different perceived hardness can be shown to exhibit different levels of transient microstates, a measure we have defined on the complexity of the microstate segmentation. We show that the human brain seems to be using 1–20% of its transient microstate capacity.

Physiological signals are at the core of affective and cognitive engineering methods which aim at providing a more humancentric perspective to engineering concepts and systems. Labelling physiological signals with meaningful words such as concentration, fatigue or effort is a hard task. Although those labels are well-documented in the medical and related literature, their meaning gets lost in translation in engineering and design sciences. Multistate analysis of physiological signals aims at alleviating this process by identifying pittfalls and errors backed by hard numerical and statistical evidence. In this paper, we use multistate analysis of EEG signals to revisit the effort-fatigue tradeoff in the conceptual design process. Many rules of thumb and intuitions may exist about the effort-fatigue tradeoff and the goal is to provide a quantitative framework where this tradeoff can bear meaning. Following our multistate analysis, we define different types of fatigue (TYPE 1-5 Fatigue) which behave differently based on our numerical analysis and conclude that fatigue and by extension effort are multidimensional concepts.