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style="font-family: -moz-fixed; font-size: 13px;" lang="x-western">Hi
all
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I am college student and I have an internship in N.I.H . I really need
to learn E_prime , but I can not make my first task right and I don't
know which steps I did wrong . Can somebody describe each step of this
task for me ? I would be grateful if somebody help me . This is the
task :
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Multitask Badre Wagner Neuron 2004
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Figure 1. Task Schematic Depicting the Order and Timing of Events
during Each Trial and Illustrating the Four Conditions at Response
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(A) All trials began with the serial presentation of three words
followed by a bias cue. Subjects used this cue to select or prepare the
expected response. Following a 3000 ms delay, a response cue was
presented in red. The subject was given 1500 ms to respond. There were
two types of Response cues, with each cueing either an Expected or
Unexpected response, resulting in four conditions at response.
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(B) When a word (Repeat) cue was presented at response, subjects
covertly repeated the word and pressed a button. On 75% of Repeat
trials, the word cued the Expected response; on the remaining 25% of
trials, the response was Unexpected.
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(C) When a number (Refresh) cue was presented, subjects covertly
repeated the word from the memory set that corresponded to that number
in ordinal position (e.g., “2” cued the second word). Again, on 75% of
the trials the number cued the Expected response, and on 25% of the
trials the response was Unexpected.
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On each trial, a 3 s delay followed presentation of the bias cue, and
then a final response cue was presented to signal the target response
to be immediately executed (Figure 1A). The response cue signaled
either the expected or an unexpected response—a manipulation of
response selection demands. Moreover, the cue stimulus either directly
mapped onto a response or required access to recently active
representations within working memory—a manipulation of refresh and
subgoal/integration demands. These conditions and their implications
for control processing are further detailed below.
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The sensitivity of PFC to “response selection” demands was tested by
arranging a mismatch on conflict trials between the expected response,
based on the bias cue, and the cued response (Figure 1B). On half of
the trials, the response cue was a word (Repeat cue), and subjects were
instructed to covertly repeat the word and press a button once having
done so. The word was always one of the three words from that trial's
memory set. Furthermore, 75% of the time the Repeat cue, and thus the
response, was the same as the word that had been expected based on the
bias cue presented prior to the delay and so was consistent with the
Expected response (i.e., no response conflict). For the remaining 25%
of Repeat trials, the response cue corresponded to one of the other
words in the memory set, thus requiring an Unexpected response.
Accordingly, during Unexpected trials, the prepared or prepotent
response was incongruent with the response signaled by the response
cue. Hence, analogous to the Stroop task, Repeat-Unexpected trials
required selection of a response pathway based on bottom-up visual
input in the face of a task-irrelevant, prepotent response (although,
in contrast to Stroop, here the prepotent response was established by a
top-down bias or selection process engaged upon presentation of the
bias cue rather than a learned preexperimental association). Thus, for
Repeat trials any sensitivity of PFC to expectation would reflect
response conflict and response selection demands.
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To test the sensitivity of PFC to refresh and subgoaling/integration
demands, we devised two additional conditions in which response
conflict was present or absent in the face of a need to execute a
subgoal entailing the integration of two cues, and to subsequently
refresh a recently active representation (Raye et al., 2002).
Specifically, in the Refresh condition, the response cue entailed a
symbolic stimulus that required retrieval of a representation from
within working memory, with some trials requiring an expected response
and others requiring an unexpected response (Figure 1C). During the
half of all events that were Refresh trials, the response cue was a
number (Refresh cue), rather than a word. As with the bias cue, the
Refresh cue referred to the ordinal position of one of the words. In
response to the Refresh cue, subjects were to covertly repeat the
corresponding word that was cued by the number (Raye et al., 2002) and
to press a button once having done so. Hence, differential sensitivity
to this condition over the Repeat condition might reflect processes
engaged to refresh a recently active representation within working
memory. Importantly, Refresh trials further required
subgoaling/integration because the symbolic response cue had to be
specified prior to response selection. That is, Refresh trials
necessitated that the response cue be compared/integrated with the bias
cue to determine if the prepared response was or was not the target
response. This integration stage entailed execution of a subgoal en
route to satisfying the global goal of executing a response independent
of whether the response was expected or not, a distinction that
differentiates this integration process from the hypothesized refresh
process. Hence, to the extent that a region of PFC is engaged in
refreshing, it should principally reveal a difference between
Refresh-Unexpected and Repeat-Unexpected. Whereas, if a region of PFC
is critical for subgoaling/integration, it should be sensitive to the
need to Refresh regardless of whether the response is expected or
unexpected, because both conditions require subgoaling and integration.
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In addition to the main effects of refreshing and
subgoaling/integration, response conflict was also manipulated within
the Refresh condition. As in the Repeat condition, for 75% of Refresh
trials the number cued the same word as had been indicated by the bias
cue, and so the response was Expected even though the representation
cueing the response (a symbolic cue) differed from the prepared
representation (the response word). For the remaining 25% of Refresh
trials, the number cued one of the other two words, and so the response
was Unexpected. Thus, as with the Repeat-Unexpected condition, the
Refresh-Unexpected condition required a response in the presence of
conflict from the prepared but irrelevant response.
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