On the relation between process models for decision making and latent variable models for individual differences

This manuscript analyzes latent variable models from a cognitive psychology perspective. We start
by
discussing
work
by
Tuerlinckx
and
De
Boeck
(2005),
who
proved
that
a diffusion model for
two‐choice
response
processes
entails
a two‐parameter
logistic
Item
Response Theory
(IRT) model
for
individual
differences
in
the
response
data.
Following
this
line
of
reasoning,
we
discuss the appropriateness of IRT for measuring abilities and bipolar traits, such as pro/contra attitudes. Surprisingly, if a diffusion model underlies the response processes, IRT models are appropriate
for
bipolar
traits,
but
not
for
ability
tests.
A reconsideration
of
the
concept
of
ability that
is
appropriate
for
such
situations
leads
to
a
new
item
response
model
for
accuracy
and
speed based on the idea that ability has a natural zero point. The model implies fundamentally new ways
to
think
about
guessing,
response
speed
and
person
fit
in
item
response
theory.
We
discuss the
relation
between
this
model
and
existing
models,
as
well
as
implications
for psychology
and psychometrics.