Age Differences in Emotional Prime Use

Even though the visual context effects were stronger for the dynamic natural emotional prime face compared to the dynamic static emotional prime face, these face effects differed also by the age of the comprehender. While all three age groups could use the direct cue, i.e., the depicted action to determine the correct role filler on-line, only older and younger adults could also use the emotional prime face. Children on the other hand did not show any facilitative effects of this indirect social cue.

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10.6.1 Younger Adults’ Positive Prime Effect

Although younger adults’ positive prime effects were present in the on-line as well as in the off-line data and although they could moreover use the prime face to anticipate the target agent, the magnitude of the positive prime effects were still relatively weak compared to the effects of the direct cue. Taking younger adults negativity bias into account (e.g., Isaacowitz et al., 2009), see also Section 3.7.1.1) these effects might have been stronger if we had used negatively congruent prime - character / sentence trials compared to only positively congruent trials. Yet, our findings suggest that emotional facial expressions, even if they are not in line with the specific emotional bias of an age group can facilitate the real-time comprehension of structurally challenging sentences of a matching emotional valence.

10.6.2 Older Adults’ Positive Prime Effect

Even though the positively matching valence between the prime face, the target agents facial expression and the sentence was in line with older adults positivity bias, they also did not show stronger real-time effects of the indirect cue. Similar to the younger adults, older adults did make use of the positive emotional prime face for on-line sentence processing. Nevertheless, their positive prime effects were as well weaker as their depicted action effects. One possible reason for these relatively weak effects might lie in the comprehension and recall tasks that participants had to perform. As discussed in Section 3.7.1.2, Reed et al. (2014) found a strong influence of task demands on older adults’ positivity bias. They report that the positivity bias was strongest in studies in which emotion processing happened unconstrained. In our studies, even though participants were not asked directly to provide a label for the emotional prime face, in the natural face version (studies 3, 5 and 6) they were occasionally asked to recall what the prime face looked like. They were moreover occasionally asked to state how the displayed characters might be feeling (only in filler trials) and they were asked to indicate ‘who was doing what to whom’ after each trial. Thus this accumulation of slightly different tasks that had to be performed throughout the experiment might have weakened older adults use of the positive prime face.

Moreover, the fact that the woman whose positive and negative facial expressions were used as dynamic natural primes had approximately the same age as our younger

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adult participants might have also played a role for older adults subtle effects of the prime face. We might in contrast have seen stronger positive prime effects for the older adults if we had, in addition, used older adults emotional faces as primes.

Several studies have reported a higher decoding accuracy, longer fixation durations, better expression identification and better memory for own-age compared to other-age faces (Ebner, He, Fichtenholz, McCarthy, & Johnson, 2010; Thibault, Bourgois, &

Hess, 2006; and see Rhodes & Anastasi, 2012 for a meta-analysis on memory of own-age vs. other-own-age faces). On the other hand, that emotions in own-own-age faces are more accurately recognized by in- compared to out-group members seems to be especially the case for negative but not so much for positive emotional facial expressions. Plus, emotion identification appears to be overall more difficult in older compared to younger faces, regardless of the identifier’s age (Riediger, Voelkle, Ebner, &

Lindenberger, 2011). Hence, using in-group instead of out-group faces in accordance with our participants’ ages might have strengthened our positive prime effects, specifically for the older adults. On the other hand, we would not expect a drastic increase in the magnitude of the face effect due to the age of the prime face, as emotion recognition for happy faces is not as strongly influenced by the age of the perceiver as it is for negatively valenced faces (cf., Riediger et al., 2011).

10.6.3 Children’s Positive Prime Effect

Even though the advantage for own-age compared to other-age faces in face recognition has also been suggested for children (Hills & Lewis, 2011; Rhodes &

Anastasi, 2012), we do not think that the positive emotional prime face would have had an effect on children’s sentence processing if we had used children’s instead of adults’ faces as primes for testing children. Rather, the missing effect of the positive emotional prime face – regardless of its degree of naturalness – might be due to an accumulation of cognitively demanding and especially still developing skills in 4-5 year old children. At this age, children are still in the process of acquiring their native language, i.e., they have not yet learned to assign thematic roles in OVS sentences when no supportive visual context is co-present (see Section 2.3). Moreover, they are also still in the process of learning to correctly identify and interpret emotional facial expressions (see Section 3.7.1.3). Hence, using this indirect social cue (which is itself still in development) in order to facilitate the processing of a linguistic structure that

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children also have not fully mastered at that age might be too cognitively demanding.

Additionally, recall that Scherf et al. (2007, see Section 3.6) demonstrated in a functional Magnetic Resonance Imaging (fMRI) study that 5-8-year old children did show significantly less face-specific activation for video sequences of natural faces in the ventral visual cortex compared to adults. However, no differences in activation were found for places or objects compared to adults. Hence, the missing effect of the indirect cue for children could further be due to the fact that they are not yet able to process faces (irrespective of their emotional valence) in the same way as adults.

Additionally, the positivity bias in children is not yet as well established as it is in older adults (see also Section 3.7.1.3). However, recent behavioral findings by Picardo, Baron, Anderson and Todd (2016) strongly support a positivity bias in 5-7-year old children. In two studies using different emotional facial expressions and different participants, Picardo et al. (2016) suggested that children in contrast to young adults rated happy facial expressions as more arousing and intense than negative facial expressions. Moreover, as they controlled for children’s ability to correctly identify all facial expressions, they excluded the possibility that this positivity bias in ratings is due to difficulties in emotion identification. Their studies hence, support neuroimaging findings that demonstrated similar amygdala activation patterns in children for positive faces compared to older but not to younger adults (Todd et al., 2012; Todd et al., 2010, see also Section 3.7.1.3). A positivity bias in children is further supported by Sato and Wakebe (2014). They asked 5-year olds and younger adults if an agent who destroyed a block castle acted intentionally or unintentionally. The agent either hit the block castle, thereby destroying or missing it;

or the agent fell into versus next to the castle, i.e., destroying or missing it. The castle could hence, be intentionally (hitting) or unintentionally (falling) destroyed; or the agent did not destroy the castle but intended to; versus the castle was not destroyed because the agent fell next to it (no intention to destroy the castle). Children in contrast to adults judged the agent’s intention based on the result of the action, i.e., if the castle was destroyed or not. Crucially, children in contrast to adults also judged the agent’s intentions as more positive, meaning that they did not think that the agent intended to destroy the castle. Hence, this recent evidence supports a positivity rather than a negativity bias in 4-5-year old children (for further discussion see also Section 3.7.1.3). However, Berman et al. (2016) and Berman, Graham, Callaway and

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Chambers (2013) found contrasting evidence supporting a negativity bias, at least for vocal affect. Additionally, Vaish et al. (2008) argue for a hard-wired negativity bias based on ontogenetic mechanisms that is present from early infancy. However, recall that this contrasts with neuroimaging studies demonstrating a higher amygdala activation for positive (versus negative) emotional faces for both children and older adults but a higher activation for negative (versus positive) emotional faces for younger adults (Mather et al., 2004; Todd et al., 2012; Todd et al., 2010), hence demonstrating a positivity bias for children and older adults but a negativity bias for younger adults. This bell-shaped development in emotional preferences directly contrasts with arguments for a hard-wired negativity bias.

Thus, whereas there is considerable evidence supporting the positivity bias in older age, there are at least some contrasting findings regarding the positivity bias in young children. Our findings that 4-5-year old children are not yet able to benefit from positive emotional faces for thematic role assignment and the processing of positively valenced OVS sentences might thus additionally be due to a weaker influence of positive emotional facial expressions on children compared to the influence on older adults.