MORE THAN MEETS THE EYE: STIMULUS-RESPONSE COMPATIBILITY EFFECTS IN EYE MOVEMENTS
Distinctions between set- and element-level compatibility have been made regarding
stimulus-response compatibility (SRC) effects. Prior research has revealed a relationship
between these two types of compatibility such that an increase in set-level effects results
in an analogous increase in element-level effects. There are different ways that location
information can be conveyed visually: location-words (“left” and “right”), directionalarrows (pointing left and right), and physical-locations (stimuli appearing in the left or
right areas of the visual field). Set-level compatibility is higher for location-words paired
with vocal “left”-“right” responses than for the other two stimulus modalities, and vice
versa for pairings with left-right keypress responses, and the element-level compatibility
effects differ in size accordingly.
My dissertation research focused on examining set- and element-level
compatibility effects within the saccadic eye-movement system. These effects were
considered within the dimensional overlap framework proposed by Kornblum,
Hasbroucq, and Osman (1990), according to which the element-level mapping effects are
an increasing function of set-level compatibility. All experiments were conducted using
introductory psychology students.
In Experiment 1, participants responded using a left-right unimanual joystick
movement or eye movement to a location-word or physical-location stimulus. In addition to an analysis of variance (ANOVA) of mean reaction time (RT) and response accuracy
for the respective conditions, compatibility effects across the RT distribution were
investigated by dividing trials into quantiles. Experiment 1 produced a set-level
compatibility effect for the congruent mapping: Eye-movement responses (rather than
joystick movements) were found to be relatively more compatible with physical-location
stimuli than with location-word stimuli. In addition, the high set-level compatibility
conditions exhibited a larger element-level mapping effect than the low set-level
compatibility conditions. RT distribution analysis showed that both eye- and joystickmovements yielded a steadily increasing element-level mapping effect across bins, except
for physical-location stimuli mapped to joystick responses, for which the function was
flat.
In Experiment 2, the location-word stimuli used in Experiment 1 were replaced by
directional-arrow stimuli. Eye movements (and not joystick movements) showed larger
set- and element-level SRC effects when paired with physical-location stimuli than with
directional-arrows. As in Experiment 1, the physical-location stimuli paired with eyemovement responses demonstrated an increase in the element-level mapping effect across
the RT distribution. However, for the three other three set-level pairings, the elementlevel mapping effects were relatively constant across the RT distribution. This pattern
further indicates a preferential benefit for eye movements paired with physical-location
stimuli.
Experiment 3 directly compared the location-word stimuli used in Experiment 1
and the directional-arrow stimuli used in Experiment 2. The element-level mapping effect
was larger for location-words than for directional-arrows, but both types of stimuli produced similar interaction patterns regarding the set-level manipulation. That is, the
differences between each response modality and stimulus type produced similar patterns
of element-level mapping effect differences. The location-word stimuli produced
consistently large effects and served as a driving factor across the set-level comparisons.
The location-words showed a large increase in element-level mapping effect across the
RT distribution compared to only a small increase for the directional-arrows, which in
both cases did not differ between eye- and joystick-movement responses.
Together the three experiments provide support for the hypothesis that eyemovement responses to physical-location stimuli are a unique, highly optimal set-level
pairing relative to location-words or directional-arrows denoting spatially relevant
location. In the context of a continuum outlining the relative position of different
response and stimulus pairings, the results imply that eye-movement responses are
similar in compatibility to joystick movements, except for the specific pairing with
physical-location stimuli.
The results offer some support for Kornblum et al.’s (1990) account that suggests
a tightly coupled relationship between set- and element-level compatibility effects. Not
only do the results provide understanding about the existence of compatibility effects
within the saccadic system, they allow for some considerations about how attention is
allocated preferentially to certain stimuli rather than others. They also enable predictions
about similar underlying mechanisms that might be involved in saccadic and manual
response modalities. Taken together, it seems that the eye-movement system adheres to
conventional notions about motoric behavior; however, it also has its own unique
properties that make it highly tuned to exogenously guided stimuli.
History
Degree Type
- Doctor of Philosophy
Department
- Psychological Sciences
Campus location
- West Lafayette