TY  - JOUR
A1  - Hohenstein, Sven
A1  - Matuschek, Hannes
A1  - Kliegl, Reinhold
T1  - Linked linear mixed models: A joint analysis of fixation locations and fixation durations in natural reading
JF  - Psychonomic bulletin & review : a journal of the Psychonomic Society
N2  - The complexity of eye-movement control during reading allows measurement of many dependent variables, the most prominent ones being fixation durations and their locations in words. In current practice, either variable may serve as dependent variable or covariate for the other in linear mixed models (LMMs) featuring also psycholinguistic covariates of word recognition and sentence comprehension. Rather than analyzing fixation location and duration with separate LMMs, we propose linking the two according to their sequential dependency. Specifically, we include predicted fixation location (estimated in the first LMM from psycholinguistic covariates) and its associated residual fixation location as covariates in the second, fixation-duration LMM. This linked LMM affords a distinction between direct and indirect effects (mediated through fixation location) of psycholinguistic covariates on fixation durations. Results confirm the robustness of distributed processing in the perceptual span. They also offer a resolution of the paradox of the inverted optimal viewing position (IOVP) effect (i.e., longer fixation durations in the center than at the beginning and end of words) although the opposite (i.e., an OVP effect) is predicted from default assumptions of psycholinguistic processing efficiency: The IOVP effect in fixation durations is due to the residual fixation-location covariate, presumably driven primarily by saccadic error, and the OVP effect (at least the left part of it) is uncovered with the predicted fixation-location covariate, capturing the indirect effects of psycholinguistic covariates. We expect that linked LMMs will be useful for the analysis of other dynamically related multiple outcomes, a conundrum of most psychonomic research.
KW  - Linear mixed model
KW  - Model linkage
KW  - Eye movements
KW  - Reading
Y1  - 2017
U6  - https://doi.org/10.3758/s13423-016-1138-y
SN  - 1069-9384
SN  - 1531-5320
VL  - 24
SP  - 637
EP  - 651
PB  - Springer
CY  - New York
ER  - 
TY  - JOUR
A1  - Dimigen, Olaf
A1  - Sommer, Werner
A1  - Hohlfeld, Annette
A1  - Jacobs, Arthur M.
A1  - Kliegl, Reinhold
T1  - Coregistration of eye movements and EEG in natural reading analyses and review
JF  - Journal of experimental psychology : General
N2  - Brain-electric correlates of reading have traditionally been studied with word-by-word presentation, a condition that eliminates important aspects of the normal reading process and precludes direct comparisons between neural activity and oculomotor behavior. In the present study, we investigated effects of word predictability on eye movements (EM) and fixation-related brain potentials (FRPs) during natural sentence reading. Electroencephalogram (EEG) and EM (via video-based eye tracking) were recorded simultaneously while subjects read heterogeneous German sentences, moving their eyes freely over the text. FRPs were time-locked to first-pass reading fixations and analyzed according to the cloze probability of the currently fixated word. We replicated robust effects of word predictability on EMs and the N400 component in FRPs. The data were then used to model the relation among fixation duration, gaze duration, and N400 amplitude, and to trace the time course of EEG effects relative to effects in EM behavior. In an extended Methodological Discussion section, we review 4 technical and data-analytical problems that need to be addressed when FRPs are recorded in free-viewing situations (such as reading, visual search, or scene perception) and propose solutions. Results suggest that EEG recordings during normal vision are feasible and useful to consolidate findings from EEG and eye-tracking studies.
KW  - EEG
KW  - eye tracking
KW  - fixation-related potentials
KW  - artifact correction
KW  - natural viewing
Y1  - 2011
U6  - https://doi.org/10.1037/a0023885
SN  - 0096-3445
VL  - 140
IS  - 4
SP  - 552
EP  - 572
PB  - American Psychological Association
CY  - Washington
ER  -