Case studies of mental models in home heat control: searching for feedback, valve, timer and switch theories

An intergroup case study was undertaken to determine if: 1) There exist distinct mental models of home heating function, that differ significantly from the actual functioning of UK heating systems; and 2) Mental models of thermostat function can be categorized according to Kempton’s (1986) valve and feedback shared theories, and others from the literature. Distinct, inaccurate mental models of the heating system, as well as thermostat devices in isolation, were described. It was possible to categorise thermostat models by Kempton’s (1986) feedback shared theory, but other theories proved ambiguous. Alternate control devices could be categorized by Timer (Norman, 2002) and Switch (Peffer et al., 2011) theories. The need to consider the mental models of the heating system in terms of an integrated set of control devices, and to consider user’s goals and expectations of the system benefit, was highlighted. The value of discovering shared theories, and understanding user mental models, of home heating, are discussed with reference to their present day relevance for reducing energy consumption

Using the notion of mental models in design to encourage optimal behaviour in home heating use

Introduction: Understanding how to influence householder’s energy consuming behaviour, could inform far reaching strategies to combat climate change. A Mental Model (MM) approach to design, to encourage optimal behaviour was explored. Challenges exist in accessing, describing and analysing user MMs and associated behaviour.Method: A method that considered bias in interpretation was developed, involving a structured interview, concept maps and graphical self-reported behaviour. Using this method, 6 householders in matched accommodation, over winter 2011/2012, participated in a home heating case study. Thermostat set point data was also collected from participant’s households. A home heating expert was interviewed using the same method, for comparison.Results and discussion: Key variations in MMs of home heating were found. The differences in user MMs from each other, and an expert, were insightful in explaining non-optimal home heating operation. These suggest design solutions that could promote or compensate for user mental models to influence energy consumption

When energy saving advice leads to more, rather than less, consumption

Energy saving technology that relies on behaviour change fails to deliver on its promise. Energy saving advice also has limited effect. This paper examines and reveals how technology and energy saving advice interacts with householders’ thought processes to influence energy consumption. A case study of three households that held a ‘Feedback’ mental model of the home heating thermostat, as defined by Kempton [1986. ‘Two Theories of Home Heat Control’. Cognitive Science 10 (1): 75–90], was undertaken to understand the driver behind differences in their home heating strategies, and the effect on energy consumption. Analysis was undertaken from five different data sources comprising: (1) boiler on durations, (2) thermostat set point adjustments, (3) self-reported strategies with home heating controls, (4) user mental model descriptions of the home heating system, and (5) Interview transcripts. The authors found that differences in user mental models of home heating at the system level explained differences in the strategies chosen at the control device level. Differences in boiler on periods were found to relate to limitations of the ‘Feedback’ mental model; that is, the model fails to consider the effect of the movement of warm air within the home and the impact of internal/external temperature differentials on heat loss rates. The authors argue that technology and advice should be tailored to the thought processes adopted by householders in order to promote behaviour that would realise intended energy savings

Mind the gap – Deriving a compatible user mental model of the home heating system to encourage sustainable behaviour

Householders' behaviour with their home heating systems is a considerable contributor to domestic energy consumption. To create a design specification for the ‘scaffolding’ needed for sustainable behaviour with home heating controls, Norman's (1986) Gulf of Execution and Evaluation was applied to the home heating system. A Home Heating Design Model (DM) was produced with a home heating expert. Norman's (1986) 7 Stages of Activity were considered to derive a Compatible User Mental Model (CUMM) of a typical Heating System. Considerable variation in the concepts needed at each stage was found. Elements that could be derived from the DM supported stages relating to action specification, execution, perception and interpretation, but many are not communicated in the design of typical heating controls. Stages relating to goals, intentions and evaluation required concepts beyond the DM. A systems view that tackles design for sustainable behaviour from a variety of levels is needed

Models of models: filtering and bias rings in depiction of knowledge structures and their implications for design

Mental models are poorly specified in three ways: in their defining criteria, their source and the bias to which they have been subjected. Literature from psychology, HCI and human factors sources was reviewed to determine the utility of 'mental models' as a design tool. The definitions and theories offered by key contributors to the notion of mental models were compared. Schematics, representing both the knowledge structures proposed in cognitive processing, as well as the layers of bias evident when forming or accessing mental models, were constructed. Fundamental similarities and differences in the use of this notion, as well as ambiguities in definition, were highlighted graphically. The need for specificity in the use of mental models was emphasised as essential for pragmatic application in design. The use of graphical comparison was proposed as a means of identifying the risk of bias and a means to categorise approaches to mental model research

Mental model interface design: putting users in control of home heating

Occupant behaviour is a key variable affecting the amount of energy used in homes. The understanding, interface and interaction with heating controls hold the potential to influence how heating is operated and, in turn, how much energy is consumed. A study is presented to test a series of hypotheses that the design of the home-heating interface can positively influence the achievement of home-heating goals, if it is specifically designed to communicate a user mental model (UMM) of how the system functions. This would encourage appropriate inhabitant behaviour. The experiment involved 20 pairs of participants matched by age, gender and home-heating experience. The participants were asked to attain a series of home-heating goals using an accelerated home-heating simulator. The impact of specific design features of a novel interface design was compared with an interface offering a traditional home-heating system experience. The evidence confirms that design features contributed to differences in UMMs, intentional behaviour and goal achievement. A mental model approach to design can be used as a means of putting users ‘in control’ of their heating system to enable them to fulfil their home-heating goals better

Human factors and ergonomics in interactions with sustainable appliances and devices

This chapter offers a much-needed perspective of the human factors considerations when exploring interactions with sustainable appliances and devices. Using the central heating system as a case study, this chapter highlights the core issues and provides key recommendations for practitioners, designers, and policy makers interested in the important area of sustainable interaction design. By providing an overview of the literature and an example of design application to illustrate the theory, this chapter makes a strong case for adopting a mental models approach to design within a system of systems perspective

Directability, eye-gaze, and the usage of visual displays during an automated vehicle handover task

The proposed next step in semi-automated vehicle technology is to allow a driver to conduct secondary tasks whilst automation is in full control of the driving task. The driver may be required to take control and promptly re-enter ‘the control loop’ if an automated feature reaches a design, geographical or capability boundary. In these circumstances it is of importance to raise the ‘Situation Awareness’ (SA) of the system through transactions between driver and vehicle. Communication literature suggests that a useful method for facilitating interactions between driver and automation is ‘directability’, guidance towards future actions or relevant pieces of information (e.g. road hazards). It is proposed that this would lead to improved SA. This study evaluated the role of directability in semi-automated vehicles by testing two research questions, how well can vocal communication from an automated assistant guide driver visual gaze, and how do drivers utilise visual displays during handover and manual driving? Participants took part in a simulated driving handover task on a highway. It was found that vocal guidance was effective in directing visual gaze. Further, the majority of visual-gaze in both handover and manual tasks was directed towards the road environment, and displays close to the road-view. This study provides additional evidence that vocal communication could serve as a reliable SA raising method, as well as provide insights into how different visual displays can be utilised for raising SA in level 3 and 4 automated vehicles

Identified handover tools and techniques in high-risk domains: using distributed situation awareness theory to inform current practices

In high-risk domains, poor shift handover has been identified as a key contributing factor in many incidents. This raises the question of: how can personnel collaborate effectively during shift changes? The vast majority of handover literature relates mainly to healthcare, aviation, energy generation and distribution domains. This review identified 19 distinct handover tools/techniques (HTTs) that domains employ to improve handover communication. The most prevalent HTT is standardisation in the form of a structured checklist, followed by the bidirectional exchange of information. This review assesses and summarises HTTs using ‘distributed situation awareness’ theory, and provides a comprehensive review on what is currently practised in high-risk domain handover, as well as a discussion around their potential contribution to raising distributed situation awareness.</p