### abstract ###
the aim of this article is to evaluate the contribution of process tracing data to the development and testing of models of judgment and decision making jdm
we draw on our experience of editing the  handbook of process tracing methods for decision research  recently published in the sjdm series
after a brief introduction we first describe classic process tracing methods thinking aloud  mouselab  eye-tracking
then we present a series of examples of how each of these techniques has made important contributions to the development and testing of process models of jdm
we discuss the issue of large data volumes resulting from process tracing and remedies for handling those
finally  we argue for the importance of formulating process hypotheses and opt for a multi-method approach that focuses on the cross-validation of findings
### introduction ###
theories of judgment and decision making jdm can be classified into two general types  formal  or as-if  models  which specify relationships between input task and context parameters and output jdm behavior  and process models  which in addition seek to model explanatory psychological mechanisms underlying such input-output relationships
within the formal modelling tradition theories are evaluated via analysis of their predictions concerning outcome judgments and decisions  and subsequent rigorous experimental tests of such predictions
alternative models are evaluated in terms of the testable predictions that distinguish them  CITATION
process models  on the other hand  can be tested and evaluated in terms of both jdm behavior and process tracing methods  which elicit and analyze observations of a range of verbal and nonverbal antecedents and concomitants of judgments and decisions
imagine you conduct a risky decision making experiment in which you observe choices and collect verbal protocols
you find that the choices conform to  say  prospect theory  CITATION   but the verbal protocol has only infrequent uses of what you coded as evidence for prospect theory e g   reference point setting  coding as gains or losses  probability
what would you conclude  that decision making conforms to prospect theory according to the choices  or that it fails to do so according to the verbal protocols
we surmise that the protocols would be seen as a subordinate  a supplementary source of data in this case
they would tend to be dismissed  if inconsistent with the choice output
in other words  we would hardly be likely to reject prospect theory on the basis of verbal protocols  or any other process data
process data somehow seem to be a subordinate source of evidence
for models that aim at predicting outcomes as-if-models this is appropriate  but not for models that aim to explain both outcome and process process models
the priority of output data is based on a natural sequence of testing dependent variables  predicting choice data is a first criterion for any model  be it a process model or an as-if-model
but beyond this first step there is no reason to prefer outcome over process
rather  for process models process data should be equally important  because they are richer than input-output data and can provide important evidence of explanatory mechanisms  CITATION
an instructive example is the work of glockner and herbold  CITATION   who show that  although prospect theory is certainly a good as-if-model  its process assumptions have to be rejected in favor of alternative models
in this paper we describe methods devised in the field of judgment and decision making jdm to enable the recording of traces of underlying processes and cognitive representations
we will describe these methods on three dimensions  their theoretical contribution  their core methodology and their key results
