Page 163 - Contributed Paper Session (CPS) - Volume 4

CPS2165 Carla Susete Gonçalves Francisco et al.

Reaction times: A new approach using new
advances in distribution theory
,1
2
Carla Susete G. Francisco , José António S. Macias , Filipa Neiva C. Ribeiro 1
1 Catholic University of Portugal, Lisbon, Portugal
2 University of Coruna, Coruna, Spain
Abstract:
Reaction times (RTs) have been an important measure in the investigation
of the cognitive process. Both psychologists and neurologists have been
engaged in the development of studies on the evaluation of models to
describe the RTs processes. A very important issue is the study of
probability distributions that describe the RTs, which more general
probability distribution families can hardly explain. Among the several
existing models, the most usual for this type of study is the LATER (Linear
Approach to Threshold with Ergodic Rate) of Carpenter (1981). Nakahara
et al. (2006) developed an extension of the LATER model, which they call
the extended LATER model (ELATER), to account for trial-by-trial variability
of both pre- and post-processes together. Moscoso (2008) develops a new
theory in which TRs are directly proportional to the difficulty of the task
and inversely proportional to the rate at which information becomes
available to solve. The possibility of fluctuations might be taken into
account, in both the information gain rate (r) and in the resting level to the
distance (∆) of threshold and then TRs will follow a distribution
corresponding to the ratio between two normally distributed variables. The
LATER model considers that the values of (r) and (∆) are statistically
independent of each other, although new pieces of evidence considered
aren´t correct, once several experiments produced the necessity for
introducing an additional parameter into the model representing the
correlation between (r) and (∆). This project aims to develop a new model
from the Fieller distribution for the ratio of two normally distributed
variables. Finally, another issue that could cast doubts on the plausibility
of LATER as a model of activity accumulation of the neurons is the
constrained linear trajectory of the accumulation of evidence of validity. A
reformulation of the LATER in terms of the diffusion process, named
LATER-d was analyzed.

Keywords
Drift-diffusion model; Ergodic Rate; LATER; Reaction time; Rise-to-
threshold model.

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