Abstracts 2005 - The Psychonomic Society

Friday Afternoon Papers 77–83
small numbers. In three experiments, participants performed magnitude
and parity judgments of digits while across-trial distance between
the digits systematically varied. The first experiment involved only
parity judgments and showed that latencies of response repetitions increased
with across-trial distance, whereas latencies of response alternations
decreased with distance. The second and third experiments
confirmed this pattern of results in switching from magnitude to parity
with informative and uninformative cues, respectively. The relevance
of the findings to current views on task switching is discussed.
2:30–2:45 (77)
Conflict and Control: Conflict-Triggered Goal Shielding and Distractor
Inhibition in Task Set Switching. THOMAS GOSCHKE,
Dresden University of Technology—Organisms pursuing goal-directed
behavior in a changing environment face two fundamental challenges:
to maintain and shield goals from distraction, on the one hand, and to
flexibly switch between goals and monitor the environment for potentially
significant stimuli, on the other. Here, I show that response conflicts
automatically trigger an enhanced shielding of the currently active
goal by inhibiting distracting information. In a cued task-switching
paradigm in which participants responded to either the shape or the
color of stimuli, conflicts induced by response-incompatible stimuli
produced increased switch costs and incompatibility effects on the
subsequent trial, indicating enhanced persisting inhibition of distracting
stimulus dimensions. In addition, response conflicts impaired
detection of prospective memory cues signaling the requirement to
switch to a different task. Results extend current theories of conflict
monitoring and cognitive control in showing that response conflicts
enhance distractor inhibition on the current trial of a task and impair
background monitoring for potentially significant stimuli.
2:50–3:05 (78)
On the Origins of the Task-Mixing Cost in the Cuing Task-Switching
Paradigm. ORIT RUBIN & NACHSHON MEIRAN, Ben-Gurion
University of the Negev (read by Nachshon Meiran)—Poorer performance
in task switching, relative to single-task conditions, is called
mixing cost (MC). In three experiments exploring the origins of MC,
participants either switched between cued shape and color tasks or
performed them as single tasks. Experiment 1 failed to support the hypothesis
that MC reflects controlled mode of processing, by showing
that a flanker interference effect was not affected by task mixing. Experiment
2 supported the hypothesis that mixed-task trials require the
resolution of task ambiguity by showing that MC existed only with ambiguous
stimuli that afforded both tasks and not with unambiguous stimuli
affording only one task. Experiment 3 failed to support the hypothesis
that holding multiple task sets in working memory (WM) generates
mixing cost, by showing that systematic manipulation of the number
of S–R rules in WM did not affect MC. The results emphasize the role
of competition management between task sets during task control.
3:10–3:25 (79)
Repetition Benefit in Task Switching. MYEONG-HO SOHN, George
Washington University, JOHN R. ANDERSON, Carnegie Mellon University,
& BRUCE C. PETERSON, George Washington University—
Performing a new task is slower than performing a repeated task, and
this difference has been attributed to the benefit of task repetition, as
well as to the cost of engaging a new task. The present study examined
whether task repetition benefits from carryover of the previous
task or priming of an upcoming task. Participants performed two tasks
(T1 and T2) on every trial, and the two tasks were either identical (task
repetition) or different (task switch). T2 was preceded by an uninformative
task cue, which was consistent with T2 (positive cue), inconsistent
(negative cue), or neutral (neutral cue). In general, T2 latency
was shorter in task repetition than in task switch. However, the benefit
of task repetition was observed only with positive or neutral cues
but not with negative cues. These results suggest that task repetition
may benefit from carryover of the recently performed task.
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3:30–3:45 (80)
Is There Volition in the Voluntary Switching Paradigm? ULRICH
MAYR & THEODORE A. BELL, University of Oregon—The voluntary
task-switching paradigm (Arrington & Logan, 2004) requires
“random” selection between tasks and promises a window into executive
task selection independently of exogenous influences present in
standard task-switching situations (Arrington & Logan, 2004). We
show here that the degree to which subjects perserverate the last trial’s
task captures unique individual-differences variance, but also that
the switch rate is under strong stimulus-driven control: “Voluntary”
switches are much more frequent when the stimulus changes than
when it stays the same. Most important, we show that individuals who
selectively slow down on no-switch trials exhibit less perseveration
and stimulus-driven effects (and thus more “voluntary” selection). We
suggest that selective slowing indicates a strategy of treating trials as
discrete events—possibly through inhibition of the preceding task.
These results not only demonstrate massive “nonvoluntary” influences
on voluntary selection, but also show how these influences can
be counteracted through strategic adaptations.
Attention II
Grand Ballroom West, Friday Afternoon, 1:30–3:10
Chaired by Shaun P. Vecera, University of Iowa
1:30–1:45 (81)
The Spatial Distribution of Object-Based Attention. SHAUN P. VE-
CERA, ASHLEIGH M. RICHARD, & ANDREW HOLLINGWORTH,
University of Iowa—The hallmark of object-based attention is that
perceptual judgments are more efficient when a target appears in an
attended object than when it appears in an unattended object. However,
the manner in which attention is oriented to objects and distributed
within objects is poorly understood. We investigated a core issue
in object-based selection: the spatial distribution of attention within
an object. We manipulated the within-object distance between a cue
and a target. Spatial distance effects within objects would support
grouped-array theories of object-based attention (Vecera, 1994). In
accord with grouped-array theories, targets were detected more quickly
near the attended end of an object than further from this attended end.
Similar results were found in a masked discrimination task, which eliminated
the possibility of shifts of spatial attention. Our results suggest
that object-based effects arise because of the spatial profile of attention
across an object, not because of shifts of attention between objects.
1:50–2:05 (82)
Spatial Attention to a Partially Occluded Object. DESTINEE L.
CHAMBERS, KYLE R. CAVE, & SIMON J. BUECHNER, University
of Massachusetts, Amherst, & SHANNON BAILEY, University
of Rochester (read by Kyle R. Cave)—Much of the evidence for objectbased
attention comes from studies with overlapping objects, and understanding
how one object can be selected when it is partly occluded
is key to understanding visual attention. We used spatial probes to
measure the allocation of attention to different parts of a target object
and distractor object when one occluded a portion of the other. The
results show that the region in which part of the target object is occluded
by a distractor receives less attention than do the visible parts
of the target. This result conflicts with findings from Haimson and
Behrmann (2001) indicating that attention was equally allocated to
unoccluded and occluded parts of the target. Comparing these results
shows that under some conditions, spatial attention can be strategically
allocated to only the visible parts of a target, while occluded
parts are inhibited.
2:10–2:25 (83)
Stimulus-Driven Attentional Capture by Objecthood. RUTH KIM-
CHI, YAFFA YESHURUN, & ALIZA COHEN-SAVRANSKY, University
of Haifa—Exogenous cues (e.g., peripheral flickers or abrupt