Experiment of visual feedback--论文代写范文精选

键盘的空格键被每个参与者使用。在写作反馈条件下,参与者由他们的文本复制到空白表。没有反馈的写作状态,参与者组成电子文本，他们提供特殊的纸组成的碳纸之间插入两个空白表。下面的essay代写范文进行详述。

Abstract 
Forty undergraduate students of psychology (mean age: 21.3 years; 27 females, 13 males) of the University of Provence participated in this experiment. Participants were randomly assigned to the two experimental groups (20 participants in the "feedback" condition, and 20 others in the "no feedback" condition). 

Material and apparatus. Participants composed their text and copied on an A4 Wacom digitizer tablet connected to an Apple LC computer with an electronic pen. A computer program in HypertalkTM language controlled the secondary reaction time task and categorized each reaction time with respect to the writer's activity (i.e., handwriting or pausing in the composing and copying tasks). More precisely, when the electronic pen was on or off the tablet for less than 250 ms participants were presumed to be primarily involved in handwriting and RTs were categorized as execution processes. 

Pauses below this threshold were also considered as reflecting low-level operations because they correspond, for example, to the transcription of a dot on the "i." Above this threshold, pauses were considered as time devoted to high-level writing processes, such as planning, translating, or reviewing, and RTs were categorized as high-level writing processes. The program did not record pen movements or length of pauses. Only length of RTs and writer's activity at the moment of the probe were recorded. Writers were sited in the front of the digitized tablet. In all phases of the experiment where probes were distributed, participants were asked to respond to the probes by pressing the spacebar of a computer keyboard with their nondominant hand. The keyboard was installed behind the digitizer tablet but shifted at left or right according to the writers' nondominant hand. 

Thus, the keyboard's spacebar was easily accessible by each participant. In the feedback writing condition, participants composed their text and copied it onto blank sheets with an electronic pen with ink. In the no feedback writing condition, participants composed their text and copied it with an electronic pen without ink. They were provided special sheets consisting of a carbon paper inserted between two blank sheets (the visible sheet was lined). Thus, writers were not able to see what they were writing but the experimenter was able to collect the texts that participants produced. In the two conditions, during the copying task, the text participants had to copy was positioned against a vertical panel in front of them, just behind the keyboard. 

Procedure. First, general instructions concerning the experiment were provided to the participants. Then, in order to compute their mean baseline RTs, participants performed a simple reaction time task. Thirty auditory probes were randomly distributed in an interval with a mean of 10 s and a range of 5 s to 15 s. Participants were asked to react as rapidly as possible whenever they detected a probe. The mean baseline RT of each participant was calculated from the 25 last RTs (the first 5 trials were treated as warming-up trials). 

In the second phase of the experiment, the secondary reaction time task was introduced. Participants were informed that during text composition they would occasionally hear auditory probes. They were again asked to react as rapidly as possible to the probes. During the composition task, probes were distributed randomly in an interval with a mean of 30 s and a range of 15 s to 45 s 2 . Participants composed a persuasive text on the following topic: The universities need more finance to renew their buildings and to buy new computers and teaching material. What do you think about an increase of the university tuition fees to cover these expenses? Can you write pro and con arguments concerning this planned increase of the students' tuition fees?

Participants were informed that they could modify their text by adding, deleting, or rewriting words or sentences. They were told to take as much time as they needed to write their text. They were reminded to concentrate fully on their text but to respond as rapidly as possible to the auditory signals. When they finished, participants had to press a special key on the keyboard to stop the secondary reaction time task. In the next phase of the experiment, participants copied their text (with a digitizer tablet) while again submitting to the secondary reaction time task. To improve the memory accessibility of the written text, participants read it twice before copying it. Participants were informed that they would continue to hear signals occasionally during the copy task and that they had to continue to respond to them as rapidly as possible by pressing the spacebar of the keyboard with their nondominant hand. The experimenter asked the participants to copy their text as it was in the original composition. More precisely, they were asked to be unaware of errors they could detect in the original copy and also of errors they might introduce to the copy. Moreover, participants were asked to copy the text in their usual handwriting style. There was no time limit to perform the copy task.

RT interference A preliminary analysis showed that the baseline RT for participants in the feedback condition (M = 550 ms) and for participants in the no feedback condition (M = 543 ms) was statistically equivalent, t (38) = 0.463,p > .05. For each participant, RT interference scores were calculated for each of the three following writers' activities: handwriting-copying, pausing-composing, and handwritingcomposing. A 2 (Feedback condition: feedback, no feedback) x 3 (Activity: handwriting-copying, pausing-composing, handwriting-composing) analysis of variance was conducted with repeated measures on the last factor. 

The feedback (M = 196 ms) and no feedback (M = 187 ms) conditions were not significantly different, F(1,38) = 0.127, p > .05. A main effect of the Activity factor was observed, F(2,76) = 9.51, p < .001. The Feedback condition x Activity interaction was significant, F(2,76) = 12.03, p < .0001. The mean RT interferences are plotted in Figure 2. To analyze the effect of suppressing the visual feedback processing demands of the high- and low-level writing processes, post hoc comparisons (Sheffé test) were conducted on each RT interference. Reaction time interference associated with handwriting-copying was significantly shorter in the feedback condition than in the no feedback condition (134 ms and 184 ms, respectively, p < .05). RT interference associated with pauses during text composition was not significantly different in the two feedback conditions (feedback = 185 ms; no feedback = 200 ms). RT interference associated with handwriting during the text composition task was significantly longer in the feedback writing condition than in the no feedback writing condition (268 ms and 178 ms, respectively, p < .01).

Writing performance Volume. An effect of feedback condition was observed on the total number of words produced during text composition, t(38) = 2.249, p < .05. In the feedback condition, participants produced fewer words (M = 199) than in the no feedback condition (M = 263, see Table 1). Writing fluency. Fluency was calculated by dividing the total composition time by the total number of words produced during text composition (including crossed-out words). The mean numbers of words per minute (wpm) were entered in a 2 (Feedback condition: feedback, no feedback) X 2 (Task: copying, composing) analysis of variance with repeated measures on the last factor. The number of wpm was not significantly affected by the feedback condition. Across the two tasks, participants produced 17.7 wpm with visual feedback and 17.2 wpm without visual feedback. The task significantly affected the number of wpm, F(1,38) = 117.42, p < .0001. During the copying task, participants wrote 20.8 wpm whereas they wrote 14.2 wpm during text composition. The Feedback condition X Task interaction was not significant (see Table 1).

DISCUSSION 
The experiment presented in this article aimed at investigating the effects of the suppression of visual feedback during text composition on the processing demands and coordination of the low- and high-level writing processes. RT interferences associated to handwriting during a copying task and to pausing and handwriting during a composing task were analyzed. Writers' productivity variables and text quality related variables were collected. Results show that RT interference associated with pauses during text composition was not significantly different in the feedback and no feedback writing conditions. By contrast, RT interference associated with handwriting during copying was longer without visual feedback than with visual feedback. Because mean RT interference associated with handwriting during a copying task evaluated the processing demands of execution processes (see introduction), the present experiment clearly supports the idea that suppression of visual feedback increases the processing demands of execution processes but not those of high-level writing processes (formulating and monitoring processes). One can argue that this finding, namely that the suppression of visual feedback affects the processing.（essay代写)

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