Introduction & Methods To study the within-trial time-course of attentional selection and the. Simon effect we analysed RT and accuracy distributions in the Egly ...
Temporary negative compatibility effects in RT and accuracy distributions in the Egly paradigm Sven Panis, Helena Wortmann, Theresa Willenbücher & Thomas Schmidt University of Kaiserslautern, Germany
Introduction & Methods
50
380
0 -100 -150 -450
360 Mean Correct RT
To study the within-trial time-course of attentional selection and the Simon effect we analysed RT and accuracy distributions in the Egly paradigm (Egly, Driver, & Rafal, 1994). In 89% of trials a cue appeared shortly at one of the four ends of two vertical or horizontal rectangles. In 75% of cued trials this cue was valid and the 50 ms target arrow appeared with a cue-target SOA of 150 ms. In the invalid-cue conditions the target either appeared at the other end of the cued rectangle (invalid-same) or at one end of the uncued rectangle (invalid-different). Participants had to discriminate the target orientation (left/right). Variables of interest are ORIENTATION (H/V), CUE-POSITION-VALIDITY (no cue or NC, valid or VA, invalid-same or IS, invalid-different or ID), COMPATIBILITY between egocentric target location and direction (compatible or C, incompatible or I), and TIME.
-850
example of VA-C-H trial
340
320
300 va
is
id
nc
CUE VALIDITY
Statistical analysis
By analysing mean correct RT and overall accuracy, most cognitive experiments have conflated the effects of their manipulations of interest with the effect of the passage of time within the response collection period. To understand a dynamical system we must measure quantities that track the output state over time to study whether and when different manipulations affect it, to try to infer the spatio-temporal interplay between different cognitive component processes. In a two-choice RT experiment, there are two types of events that can end the measurement of the passage of time in a trial: the occurrence of a correct response and of an error. Here we employ discrete-time competing-risks event history analysis (Allison, 2010; Singer & Willett, 2003). First, the hazard function tracks the tendency to respond over time by estimating the conditional probability that a response will occur sometime during time bin t, given that the response did not yet occur before the start of time bin t (i.e., given that the waiting time has increased until the start of bin t): h(t) = Prob(RT=t|RT≥t). Second, the conditional accuracy function tracks the probability over time that a response observed sometime during bin t is correct: CA(t) = Prob(correct|RT=t). AVERAGE ACROSS ALL SUBJECTS (N = 10)
SAME PATTERN AS AVERAGE FOR 5 SUBJECTS
UNEXPECTED NCE IN ca(t)-VA FOR 5 SUBJECTS
* 8 of 10: Extra response occurrence (increase in hazard) due to ALLOCENTRIC target location around 180 ms.
+
+ VA
- > + IS
+ < ID
+
+ NC
* 10 of 10: Unexpected errors in compatible VAca(t) for H and/or V => ACTIVE INHIBITION. * Strong NCE in IS-x-H and ID-x-V => inhibition of response triggered by target location wrt focus attention.
Location Cue
/ /
/ /
Left Left
Left Left
Right Right
Right Right
Left Left
Left Left
Left Left
Left Left
Left Left
Left Left
Left Left
Left Left
Left Left
Left Left
Allocentric
Left Up
Left Up
Left Up
Left Up
Left Up
Left Up
Left Up
Left Up
wrt focus attention
Up-Left Up-Left up Left Left
Up-Left Up-Left up Left Right
/ / up Left Left
/ / up Left Right
Left Left up Left Left
Left Left up Left Right
Up Up up Left Left
Up Up up Left Right
Location Target Egocentric
Object Location Target Orientation
Conclusions Traditionally, the egocentric irrelevant target location activates the corresponding response (direct route) which can interfere with the controlled response
(grey dotted arrow). Our data show the additional involvement of allocentric location coding, and of location coding with respect to the focus (not the movement) of attention. Whether one observes an overall positive or negative compatibility effect thus depends on cue-validity AND orientation (the Egly design contains a confound). To explain our results we need to assume active inhibition (probably through the basal ganglia) of any premature response activation due to task-irrelevant spatial information.
References
Allison, P. D. (2010). Survival analysis using SAS: A practical guide, Second Edition. SAS Institute Inc., Cary, NC, USA. Egly, R., Driver, J., & Rafal,R.D.(1994). Shifting visual attention between objects and locations: Evidence from normal and parietal lesion subjects. JoEP:General, 123 (2), 161-177. Lu, C.-H., & Proctor, R. W. (1995). The influence of irrelevant location information on performance: A review of the Simon and spatial Stroop effects. Psychonomic Bulletin & Review, 2 (2), 174-207. Singer, J. D., & Willett, J. B. (2003). Applied longitudinal data analysis: Modelling change and event occurrence. New York: Oxford University Press Inc.
