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<Paper uid="P99-1056">
  <Title>The grapho-phonological system of written French: Statistical analysis and empirical validation</Title>
  <Section position="4" start_page="437" end_page="439" type="intro">
    <SectionTitle>
2. Empirical study: Grapheme frequency
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    <Paragraph position="0"> and grapheme entropy To assess readers' sensitivity to grapheme frequency and grapheme entropy we collected naming latencies for pseudowords contrasted on those two dimensions.</Paragraph>
    <Section position="1" start_page="438" end_page="439" type="sub_section">
      <SectionTitle>
2.1. Method
Participants. Twenty French-speaking students
</SectionTitle>
      <Paragraph position="0"> from the Free University of Brussels took part in the experiment for course credits. All had normal or corrected to normal vision.</Paragraph>
      <Paragraph position="1"> Materials. Two lists of 64 pseudowords were constructed. The first list contrasted grapheme frequency and the second manipulated grapheme entropy. The grapheme frequency and grapheme entropy estimates for pseudowords were computed by averaging respectively grapheme frequency or grapheme entropy across all graphemes in the letter string. Low and high values items were selected among the lowest 30% and highest 30% values in a database of about 15.000 pseudowords constructed by combining phonotactically legal consonant and vocalic clusters.</Paragraph>
      <Paragraph position="2"> The frequency list comprised 32 pairs of items. In each pair, one pseudoword had a high averaged grapheme frequency, and the other had a low averaged grapheme frequency, with entropy kept constant. Similarly, the entropy list included 32 pairs of pseudowords with contrasting average values of entropy and close values of average grapheme frequency.</Paragraph>
      <Paragraph position="3"> In addition, stimuli in a matched pair were controlled for a number of orthographic properties known to influence naming latency (number of letters and phonemes; lexical neighborhood size; number of body friends; positional and non positional bigram frequency; grapheme segmentation probability; grapheme complexity). Procedure. Participants were tested individually in a computerized situation (PC and MEL experimentation software). They were successively tested in a immediate naming and a delayed naming task with the same stimuli. In the immediate naming condition, participants were instructed to read aloud pseudowords as quickly and as accurately as possible, and we recorded response times and errors. In the delayed naming task, the same stimuli were presented in a different random order, but participants were required to delay their overt response until a response signal appeared on screen. The delay varied randomly from trial to trial between 1200 and 1500 msec. Since participants are instructed to fully prepare their response for overt pronunciation during the delay period, the delayed naming procedure is meant to provide an estimate of potential artefactual differences between stimulus sets due to articulatory factors and to differential sensitivity of the microphone to various onset phonemes.</Paragraph>
      <Paragraph position="4"> Pseudowords were presented in a random order, different for each participant, with a pause after blocks of 32 stimuli. They were displayed in lower case, in white on a black background. In the immediate naming task, each trial began with a fixation sign (*) presented at the center of the screen for 300 msec. It was followed by a black screen for 200 msee and then a pseudoword which stayed on the screen until the vocal response triggered the microphone or for a maximum delay of 2000 msec. An interstimulus screen was finally presented for 1000 msee. In the delayed naming task, the fixation point and the black screen were  followed by a pseudoword presented for 1500 msec, followed by a random delay between 1300 and 1500 msec. After this variable delay, a go signal (####) was displayed in the center of the screen till a vocal response triggered the microphone or for a maximum duration of 2000 msec. Pronunciation errors, hesitations and triggering of the microphone by extraneous noises were noted by hand by the experimenter during the experiment.</Paragraph>
    </Section>
  </Section>
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