Process tracing in decision making

The methodology derived from the information processing approach, often referred to as process tracing, has been used to uncover the cognitive processes

preceding the decision maker’s response (Payne et al., 1978). There are several process-tracing methods that have been applied in decision-making research. According to Schulte-Mecklenbeck, Kühberger and Ranyard (2011), they can loosely be classified into three groups: a) methods for tracing information acquisition (e.g. information boards, eye tracking and active information search); b) methods for tracing information integration and evaluation (e.g. thinking aloud and structured response elicitation), and c) methods for tracing physiological, neurological, and other accompanying cognitive processes (e.g. measurement of reaction time, galvanic skin conductance, pupil dilation and neuronal techniques of location). As one of the aims of this doctoral dissertation is to explore information search behaviour that precedes a final choice, in the next section, I focus on explaining the methods for tracing information acquisition.

2.2.1.1 Information boards

This is a process-tracing technique where participants acquire information by opening envelopes from a matrix of envelopes attached to a sheet of cardboard. Each

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envelope contains a card with some text on it. To acquire a specific piece of

information, the participant has to take a card out of the appropriate envelope, turn it around, read it, and place it back into the envelope (Payne, 1976; Wilkins, 1967).

This technique provides data regarding what information the decision maker seeks, the sequence of information acquired, and how much information is acquired (Kühberger, Schulte-Mecklenbeck, & Ranyard, 2011). In the late 1970s, information boards became more sophisticated due to the introduction of computer-based

information acquisition systems. Information boards were therefore no longer the only type of presentation devices. Instead, computer monitors were introduced for the presentation purposes and keypresses were used to indicate which cells should be opened (Payne & Braunstein, 1978). Ten years later, the introduction of a computer mouse has led to the further development and introduction of the Mouselab system which is, as the name suggests, a system that uses a mouse to perform various decision experiments (Bettman, Johnson, & Payne, 1990; Johnson, Payne, Schkade, & Bettman, 1989). More specifically, this system could have been used to present the experiment instructions as well as a decision problem using one of five possible types of screen layout (e.g. matrix, gamble, decision-tree). In addition, it could have automatically recorded the content of the acquired information, the duration of each acquisition and search order, and choice (Johnson et al., 1989), which was a significant improvement compared to its ancestor, simple information boards. Currently, there are various more advanced (and freely available) online or offline versions of Mouselab system such as MouselabWEB (Willemsen & Johnson, 2008) or MouseTracker (Freeman & Ambady, 2010).

2.2.1.2 Eye tracking

Eye tracking refers to a process-tracing technique where participants’

information acquisition behaviour is traced by recording their eye movements.

increasingly popular over the last couple of decades (Kühberger et al., 2011). There are two main assumptions which closely connect eye movements to cognitive processes, namely the immediacy and the eye-mind assumption (Just & Carpenter, 1980). The immediacy assumption suggests that the mind follows the eye, i.e. information is interpreted as soon as it is encountered, at the expense of possible false initial

interpretations. The eye-mind assumption suggests that the eye follows the mind, i.e.

the eye remains fixated on an object as long as this object is being processed.

In a way similar to Mouselab, computer screens are used to present information in experiments when recording eye movements. However, instead of using a computer mouse to choose pieces of information, decision makers simply look at the information presented on the screen. The information acquisition process therefore resembles a more natural situation (Reisen et al., 2008). The eye tracking equipment records

saccadic, i.e. rapid, voluntary movements from one object to another, and non-saccadic eye movements, i.e. focusing on a single point or object of interest (Russo, 2011).

Parameters of specific interest for decision researchers are saccadic movements and fixations. Therefore, to draw inferences about cognitive processes, one can explore the tempo, amplitude, duration or latency of saccadic movements and the duration,

frequency and scanning path of fixations (Kühberger et al., 2011).

Generally, eye tracking techniques can be divided into two groups: a group focusing on measuring the position of the eye relative to the head and a group focusing on measuring the orientation of the eye in space, or the so called point of regard (i.e.

gaze point). There are four categories of eye movement measurement methodologies used to estimate the point of regard. These involve the measurement of: electro-oculography, i.e. measuring the position of the eye by placing skin electrodes around the eye and recording potential differences; scleral contact lens/search coil, i.e.

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attaching a mechanical or optical reference object mounted on a contact lens and then positioning it directly on the eye; photo-oculography or video-oculography, i.e.

measuring the distinct characteristics of the eyes under rotation/translation, and video-based combined pupil/corneal reflection, i.e. measuring the point of regard by either keeping the head position fixed or by measuring features such as corneal reflection and the pupil centre (Duchowski, 2007; Young & Sheena, 1975). The last category, video-based combined pupil/corneal reflection, is the prevailing method for estimating the point of regard, and has made eye tracking more convenient to use and therefore applicable in a broad range of research topics.

Further advancements in the field have led to the development of the two distinct groups of eye trackers: remote eye trackers (i.e. desktop eye trackers) and mobile eye trackers. The leading manufacturers in this field are SR Research with the EyeLink system, SensoMotoric Instruments (SMI) and Applied Systems Laboratory (ASL) with Tobii Technology (Holmqvist et al., 2011). Recently, eye tracking has been receiving growing interest from the field that develops virtual reality. Therefore, there are already several available solutions on the market. This combination of

methodologies has great potential to make research in “natural” environments more accessible, and therefore enhance the external validity of experiments.

2.2.1.3 Active information search

Active information search (AIS) refers to a process-tracing technique where participants only receive a basic description of the decision task. Therefore, to receive additional information, a participant needs to ask questions (Kühberger et al., 2011).

This method was first introduced by Engländer and Tyszka (1980) and later developed by Huber, Wider and Huber (1997) who wanted to develop a method which would require less reactive information presentation or, put differently, participants would not be required to use a specific, already predetermined, piece of information.

participant with only a necessary description of the decision task. To minimize the danger of influencing the participant, the description should be as short as possible.

However, the description also needs to be rich enough to enable the participant to formulate questions. Next, to obtain more information about the task from the

experimenter, the participant needs to ask questions. The participant can ask any type and as many questions as she wants, as well as repeat already asked questions. To avoid situations where the experimenter answers the questions and therefore potentially influences the participant, the questions are recorded, and answers are given on small cards from a list of already prepared answers. Therefore, for each decision task, pilot studies are used to optimize the short description of the task and to find as many questions as possible, which allows preparing the list of answers. However, if the participant asks a question which was not encountered during the pilot study, the experimenter needs to answer it during the experiment by improvising. The probability of new questions asked should therefore be small.

This method was further developed by Huber, Beutter, Montoya and Huber (2001) who introduced a structured version of the AIS. More specifically, instead of leaving the formulation of questions completely to the participant, in this version, she can choose a question from a list of questions and ask them to the experimenter one at the time. Questions are structured based on different types of questions identified in Huber et al. (1997). Some of the examples are questions concerning the probability of an event, questions dealing with the participant’s control over the external event or negative consequences, questions requiring information regarding what can be done in case of a negative event, questions regarding certain or uncertain consequences of a specific alternative and so on. In the standard version of AIS method, the type, frequency and sequence of the collected information are recorded, whereas in the

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computerized version (e.g. WebDiP system – Web Decision Processes), one can also record the reading time (Kühberger et al., 2011).