Contacto con los participantes y recogida de datos

8. Experiment – Older Adults

8.1 Experiment 6

8.1.1 Participants

40 adults between 60 and 80 years of age (Mean: 67.1, SD: 6.1) participated in the experiment. All participants were monolingual native speakers of German and had normal or corrected-to-normal vision. Older adults were recruited by flyers distributed in the University, the city center of Bielefeld and senior centers in Bielefeld. Testing took place in the eye-tracking laboratory of the Language and Cognition Group. They received 10 Euro for their participation and testing took approximately 60 minutes in total.

8.1.2 Materials and Cognitive Tests

Materials were identical to experiment 3 (i.e., only the target agent smiled; the patient had a neutral expression and the distractor character a negative expression, the prime face was natural). For the older participants, additional cognitive tests were administered prior to the eye-tracking study. These tests were selected subtests of the Wechsler Intelligenztest für Erwachsene (WAIS, Wechsler, 1981). Cognitive performance was measured by using the picture completion, the digit-symbol mapping, the digit span, the similarities subtest (Wechsler, 1981) and a verbal fluency test (a subtest from Aschenbrenner, Tucha, & Lange, 2000). The latter required participants to name as many examples of a category (animals) as possible and as many words with an initial letter (the letter ‘L’) as possible within one minute. All subjects were given the same tests in the same order and with the same time limits to be completed. The cognitive tests ensured that on-line and off-line results of the eye-tracking study were not confounded by between-subject differences in cognitive performance, such as verbal, working and spatial memory. Administering the cognitive tests took approximately 15 minutes.

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8.1.3 Hypotheses

Taking older adults’ strong bias towards positive emotions into account (see Section 3.7.1.2), we hypothesized that this age group would show stronger or earlier effects of the emotional prime in real-time sentence processing and stronger effects on question answering. Effects of the emotional prime were hence predicted to arise earlier during sentence processing compared to the younger adults who showed the first effects of the positive prime in the Adverb region. Moreover, since the prime effects were only marginal in younger adults, we predicted stronger effects here.

Regarding the depicted action, we did not predict differences from the younger adults in the use of the direct cue for OVS sentence processing and thematic role assignment. Nevertheless, regarding older adults general decline in cognitive functions (Salthouse, 2010), it was also possible that the visual context effects emerged later during on-line sentence processing compared to younger adults.

8.1.4 Results and Discussion

8.1.4.1 Eye-movement Results

The results for the older adults revealed a main effect of action in the Adverb (F1(1,39)= 17.896, p< .05, F2(1,15)= 3.166, p= .095), Verb-Adverb (F1(1,39)= 16,398, p< .05, F2(1,15)= 4.097, p= .061) and the Long region (F1(1,39)= 2.797, p= .102).

This effect can be seen in Graph 27, which also shows that the action effect only emerged at the end of the Verb region, i.e., where the blue and the red lines start to diverge. Hence, older adults were delayed by one word region compared to the younger adults (see Graph 7), i.e., the effect emerged at the same time as the action effect for the children (see Graph 23).

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Graph 27: Time course for the eye-movement results by condition (exp. 6).

Interestingly, the interaction between action and prime was trending in the subject analysis in the Adverb region (F1(1,39)= 2.693, p= .109). Graph 28 illustrates that this interaction was driven by the depicted action. However, it suggests that older adults also seem to have made use of the positive prime face even when no action was present compared to the no-cue condition. In the time course graph (Graph 27) this can be seen right at the beginning of the Adverb region, i.e., when the emotional valence of the adverb became available (where the solid blue line diverges from the dotted blue line). We have to keep in mind however, that the failure to find a significant interaction might not just be due to the weak effects of the emotional prime but also to the fact that there were only 4 data points per subject, i.e., 160 in total that could be used to yield an interaction between prime and action.

Graph 28: Mean log ratio of looks for the interaction between prime and action in the Adverb region (not sign., exp. 6). Error bars show the standard error.

0 0.5 1 1.5 2

positive prime incongruent prime

mean log ratio of looks

Interaction Prime x Action (Adverb Region)

depicted action no action

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Crucially, the results yielded a marginal main effect of prime in the subject analysis of the NP2 region (F1(1,39)= 3.785, p= .059). Graph 29 indicates that older adults showed a preference to look at the target agent when they had been primed with a positive facial expression compared to an incongruent prime.

Graph 29: Mean log ratio of looks for the main effect of prime in the NP2 region (F1, exp. 6). Error bars show the standard error.

However, as this effect only emerged in the NP2 region, older adults do not seem to have made use of the positive prime face to anticipate the correct role filler. As the time course graph (Graph 27) shows, the solid lines (the prime condition) only diverge late during the NP2 region from the dotted lines (the incongruent prime condition). Hence, it rather seems that older adults kept the emotional prime face in memory and reactivated its valence again when they heard the target agent named (perhaps to match the prime face valence with the positively congruent facial expression of the target agent).

However, regarding the delay for the action effect compared with younger adults, older adults may simply integrate visual cues more slowly than younger adults. For both the action and the prime effect, they were delayed by one word region.

8.1.4.2 Accuracy Results

The accuracy results for the older adults yielded a marginal main effect of action (F1(1,39)= 3.162, p= .083, F2(1,15)= 9.567, p< .05). The means indicate that older adults answered more comprehension questions correctly when an action was (vs. was not) depicted in the scene (Graph 30). By contrast, the positive prime did not have an

0 0.5 1 1.5 2 2.5

positive prime incongruent prime

mean log ratio of looks

Main Effect of Prime (NP2 Region)

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effect on the accuracy results. Nevertheless, they answered 91% of the face-recall questions correctly suggesting they had no problems in recalling the valence of the emotional prime face. These results thus underline the eye-tracking results regarding the facilitative effect of the depicted action. However, the emotional prime face did not seem to improve participants’ accuracy in answering the comprehension question.

Graph 30: Accuracy for the main effect of action (exp. 6). The y-axis displays the percentage of correctly answered trials averaged across participants. The percentages are shown in the center of each bar.

8.1.4.3 Cognitive Test Results

Older adults’ cognitive test scores are shown in Graph 31. As can be seen in this graph, they performed best in the Similarities task and worst in the Digit-Symbol Mapping task. The mean for the Verbal Fluency task was 38.825 generated words. In order to test whether accuracy results and the cognitive test scores correlate with each other, we computed Spearman’s rho¹⁹. The result yielded a medium-size but significant correlation (rs= .372, p< .05). Graph 32 illustrates this correlation and suggests that although most subjects performed at ceiling in answering the comprehension question, high accuracy scores do not necessarily also have to imply a high performance in the cognitive tests.

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19 !Spearman’s rho was chosen over Pearson’s correlation because both variables were not normally distributed.!

92 86

75 80 85 90 95 100

depicted action no action

percent accuracy