### abstract ###
in two studies on mobile phone purchase decisions  we investigated consumers' decision strategies with a newly developed process tracing tool called interactive process tracing iapt
this tool is a combination of several process tracing techniques active information search  mouselab  and retrospective verbal protocol
after repeatedly choosing one of four mobile phones  participants formalized their strategy so that it could be used to make choices for them
the choices made by the identified strategies correctly predicted the observed choices in  NUMBER  percent  experiment  NUMBER  and  NUMBER  percent  experiment  NUMBER  of the cases
moreover  in experiment  NUMBER  we directly compared mouselab and eye tracking with respect to their impact on information search and strategy description
we found only minor differences between these two methods
we conclude that iapt is a useful research tool to identify choice strategies  and that using eye tracking technology did not increase its validity beyond that gained with mouselab
### introduction ###
identifying the processes that underlie judgment and decision making has been of great interest to researchers for several decades already
in this context  two major paradigms have been used  structural modeling and process tracing  CITATION
structural modeling aims to uncover psychological processes by relating the provided information to the decisions or judgments  typically via multiple linear regression analysis
the parameters in these models are thought to represent important features of participants' decision strategies  for instance  if a particular attribute receives a high weight in a regression equation it is interpreted as being very important for the decision maker
despite its popularity  this approach has been criticized for ignoring the predecisional phase  that is  the processes that take place between stimulus presentation and final decision
for example  svenson  CITATION  concluded that it is  gradually becoming clear that human decision making cannot be understood simply by studying final decisions  p  NUMBER  and  similarly  payne  braunstein  and carroll  CITATION  argued that the  input-output analyses that have been used in most decision research are not fully adequate to develop and test process models of decision behavior  p  NUMBER 
as a response to these and other objections against structural modeling  CITATION   payne  CITATION  and others developed the process tracing approach by adapting methods from research on human problem solving  CITATION
as opposed to structural modeling  the aim of process tracing is to directly describe the processes taking place during the predecisional phase
to achieve this  the participants' information search and integration is closely observed while they work on the decision task
frequently used methods within this paradigm are information boards  CITATION   verbal protocols  CITATION   the recording of eye movements  CITATION   and the method of active information search  CITATION
in the following  we briefly describe these process tracing methodologies and discuss their strengths and weaknesses
we then present a new tool called interactive process tracing iapt  which we developed to identify the decision processes underlying preferential choice
iapt uses various elements of the process tracing measures mentioned above to combine their strengths and simultaneously overcome some of their weaknesses
we subsequently describe two experiments in which we successfully applied iapt to identify participants' decision strategies
