DESARROLLO DE LAS SESIONES

FIGURE 5.3a. Individual memory scores as a function of repetition rate,

lists 1-4, Experiment 2.

FIGURE

5.3b. Mean memory scores of each group as a function of

A marginal speed difference occurred with the two short English lists, probably due to their compilation according to Lenneberg's (1967) "rule o f thumb", where word length can be operationalised as the number o f syllables. However, syllable length also contributes to word length (Baddeley et al., 1975; Cowan et al., 1992). Thus List 3 (long sign/short English) may have been repeated more slowly by the Oral group because it contained more long vowels and words o f longer canonical form than its short English partner (List 1: short sign/short English). This might account for the Sign length x English length interaction. Because the repetition times o f the Oral group on the two long English lists were almost identical, the finding that the short English list took longer to repeat at the long sign length would have spuriously inflated the influence o f sign length for this group. This would reduce the likelihood o f a Sign length x Group interaction for repetition and memory performance, as was indeed the case.

The performance o f the "hybrid" SE group fell between the performance o f the two remaining groups. This gives added weight to the conclusion that item length may be a factor in the recall o f all three groups. For example, the influence o f sign length on memory was least for the Oral group, greater for the SE group, and greatest for the Auslan group. This is exactly what would be expected o f subjects whose reliance on sign is absent, partial, or total, respectively. As anticipated, the impact o f English length was a mirror image o f these results.

The different patterns o f response were all the more striking in view o f the finding that the groups did not differ on their overall memory score, suggesting that general cognitive ability factors were not influencing the outcome. The absence o f overall group differences also suggests that cherological coding cannot simply be equated with "movement memory", for which normally-hearing subjects generally show a smaller span compared to their memory for words (Smyth, Pearson, & Pendleton, 1988).

The generality o f these conclusions remain untested however. As is evident from the literature, the coding performances o f the deaf are highly susceptible to task demands. For this reason, and because o f the need to clarify the sign length effect, it was decided to assess the robustness o f this outcome by testing for item length effects with orthographic stimuli in Experiment 3.

5.4

Experiment 3: Orthographic presentation and the item length effect

5.4.1 Overview of Experiment 3

In Experiment 3, the aims and methodology were identical to those of Experiment 2 in all major respects, with two exceptions: the timed repetition measure and the memory stimuli. The former now comprised a reading task. The latter incorporated the four lists used previously, but these were presented orthographically on a VCR monitor.

The reading task was identical to that used in Experiment 1. It was used again here because the orthographic presentation o f the memory lists dictated that decoding o f print was an integral part o f the task - a part that the repetition test tapped only minimally.

The shift from primary linguistic presentation in Experiment 2 to orthographic presentation in Experiment 3 allowed an assessment o f the impact o f presentation condition upon memory. If the span o f any group were affected by presentation condition, this would indicate that performance could be affected by factors apart from rehearsal speed (such as reading ability or speechreading ability), and that these factors would have to be considered in any comprehensive account o f the memory deficit o f deaf people.

However, it was not expected that memory spans would differ in these two experiments, even though primary linguistic presentation may facilitate recall in other contexts (Poizner, Bellugi, & Tweney, 1981). For the signers, the small set size and opportunities for familiarisation were expected to counteract any difficulties o f the print- to-sign translation. Additionally, eight blocks displaying each printed word and a picture o f its corresponding sign were in view o f the subject throughout the session.

In the case o f the Oral group, despite the well-documented difficulties of speechreading (Berger, 1972; Clouser, 1977; Conrad, 1977a; Jeffers & Barley, 1971; Mogford, 1987; Summerfield, 1987), no subject was expected to be disadvantaged in Experiment 2, because o f high contextual support: each item had only to be discriminated from seven others, all eight possibilities being displayed on the blocks in front o f the subjects. A small response set and the provision o f contextual cues are known to dramatically facilitate recall o f lipread material (Lyxell & Ronnberg, 1987). Lipreading each list in Experiment 2 may also have been enhanced by the inclusion of common nouns only, which are generally easier to lipread than articles, pronouns and conjunctions (Pickett, 1980).

5.4.2 Predictions

The first three predictions were identical to those o f Experiment 2. These were:

(i) Group 1 (Auslan):

Short signs (Lists 1 and 2) would be read faster and recalled better than long signs (Lists 3 and 4).

(ii) Group 3 (Oral):

Short words (Lists 1 and 3) would be read faster and remembered better than long words (Lists 2 and 4).