  We present iScale, a survey tool for the retrospective elicitation of
longitudinal user experience data. iScale employs sketching in imposing a
process in the reconstruction of one's experiences with the aim to minimize
retrospection bias. Two versions, the Constructive and the Value-Account
iScale, were motivated by two distinct theories on how people reconstruct
emotional experiences from memory. These two versions were tested in two
separate studies. Study 1 aimed at providing qualitative insight into the use
of iScale and compared its performance to that of free-hand sketching. Study 2
compared the two versions of iScale to free recall, a control condition that
does not influence the reconstruction process. Significant differences between
iScale and free recall were found. Overall, iScale resulted in an increase in
the amount, the richness, and the test-retest reliability of recalled
information. These results provide support for the viability of retrospective
techniques as a cost-effective alternative to longitudinal studies.
