archives@tulane.edu / Making eye contact is one of the earliest, most important forms of communication. Newborns are sensitive to adults’ gaze direction (Farroni, Massaccesi, Pividori, & Johnson, 2004), and by 4 months infants learn more about an object that an adult has looked at (Reid & Striano, 2005). Emotional facial expressions influence infants’ scanning of adults’ eyes (Shepard & Spence, 2012), which may affect their sensitivity to eye gaze cues. In two experiments, we examined the effects of silent dynamic emotional messages on 6-month-old infants’ scanning of face features, as well as their sensitivity to and learning from eye gaze cues. In Experiment 1, infants completed a gaze cueing task in which speakers delivered silent approving, comforting, prohibition, and neutral messages and then shifted their eye gaze to a peripheral target. Although infants showed increased attention to the eyes during prohibition and comforting messages, all infants showed enhanced gaze cueing in the context of approving messages. Moreover, female infants showed trend-level gaze cueing following approving messages, whereas male infants showed trend-level gaze cueing following neutral messages. In Experiment 2, a separate group of infants completed a similar gaze cueing task that included a visual paired comparison test phase to examine learning of the gaze-cued and non-cued targets, based on the hypothesis that increased sensitivity to gaze cues would enhance learning of the cued targets. As in Experiment 1, infants showed increased attention to the eyes during comforting messages. However, we did not find any reliable gaze cueing effects. Infants spent more time looking at test targets following approving messages but did not show evidence of enhanced learning of cued targets. Overall, findings from both experiments suggest that 6-month-olds are more responsive to gaze cues in the context of approving messages, underscoring the significance of positive infant-directed interactions to the development of early joint attention. We conclude by discussing clinical implications, limitations (including a relevant error in Experiment 2), and future directions. / 1 / Claire Frances Noonan

In their first year, infants’ ability to follow eye gaze to allocate attention shifts from being a response to low-level perceptual cues, to a deeper understanding of social intent. By 4 months infants look longer to uncued versus cued targets following a gaze cuing event, suggesting that infants better encode targets cued by shifts in eye gaze compared to targets not cued by eye gaze. From 6 to 9 months of age infants develop biases in face processing such that they show increased differentiation of faces within highly familiar groups (e.g., own-race) and a decreased differentiation of faces within unfamiliar or infrequently experienced groups (e.g., other-race). Although the development of cued object learning and face biases are both important social processes, they have primarily been studied independently. The current study examined whether early face processing biases for familiar compared to unfamiliar groups influences object encoding within the context of a gaze-cuing paradigm. Five- and 10-month-old infants viewed videos of adults, who varied by race and sex, shift their eye gaze towards one of two objects. The two objects were then presented side-by-side and fixation duration for the cued and uncued object was measured. Results revealed 5-month-old infants look significantly longer to uncued versus cued objects when the cuing face was a female. Additionally, 10-month-old infants displayed significantly longer looking to the uncued relative to the cued object when the cuing face was a female and from the infant’s own-race group. These findings are the first to demonstrate that perceptual narrowing based on sex and race shape infants’ use of social cues for allocating visual attention to objects in their environment.

Our ability to be active agents in the world depends on our cognitive system to collect complex multisensory information, i.e. information coming from different senses, and integrate it appropriately. One fundamental topic of interest in the study of cognition is to understand the consequences of deafness on the organization of brain functions, specifically when one sensory modality is either lost or the information coming from that sensory modality is limited. In my work I used the spatial cueing paradigm to study how visual attention and selection is affected by diverse grades of congenital or acquired deafness in different life stages. The goal of the first study was to validate an integrated approach of covert and overt orienting to study social and non-social cueing of attention in hearing adults. Specifically, I examined manual and oculomotor performance of hearing observers performing a peripheral discrimination task with uninformative social (gaze cue) and non-social cues (arrow cue). In Experiment 1 the discrimination task was easy and eye movements were not necessary, whereas in Experiment 2 they were instrumental in identifying the target. Validity effects on manual response time (RT) were similar for the two cues in Experiment 1 and in Experiment 2, though in the presence of eye movements, observers were overall slower to respond to the arrow cue compared to the gaze cue. Cue-direction had an effect on saccadic performance before the discrimination was presented and throughout the duration of the trial. Furthermore, I found evidence of a distinct impact of the type of cue on diverse oculomotor components. While saccade latencies were affected by whether the cue was social or not, saccade landing positions were not affected by cue-type. Critically, the manual validity effect was predicted by the landing position of the initial eye movement. This work suggests that the relationship between eye movements and attention is not straightforward. In hearing adults, in the presence of eye movements, saccade latency was related to the overall speed of manual response, while eye movements landing position was closely related to manual performance in response to the validity of the cues. In the second study, I used the above-mentioned approach to investigate the impact of early profound deafness on the oculomotor control and orienting of attention to social and non-social cues. Previous research on covert orienting to the periphery suggests that early deaf adults are less sensitive to uninformative gaze cues, though were equally or more affected by non-social arrow cues. The aim of this second study was to investigate whether spontaneous eye movement behavior helps explain the reduced contribution of this social cue in deaf adults. Twenty-five deaf and twenty-five age-matched hearing observers took part in the experiment. In both groups, the cueing effect on RT was comparable for the gaze- and arrow-cue, although deaf observers responded significantly slower than hearing controls. While deaf and hearing observers responded equally to the cue presented in isolation, deaf participants relied significantly more on eye movements than hearing controls once the discrimination target was presented. Saccade landing position in the deaf group was affected by validity but not by cue type while latency was not modulated by these factors. Saccade landing position was also strongly related to the magnitude of the validity effect on RT, such that the greater the difference in saccade landing position between invalid and valid trials, the greater the difference in manual RT between invalid and valid trials. This work suggests that the contribution of overt selection in central cueing of attention is more prominent in deaf adults and determines the manual performance. The increase in eye movements and overall slower responses in deaf observers may act as an adaptive strategy to balance the need for accuracy in a context where vision and visual attention are used to monitor the surrounding environment in the absence of auditory input. This tendency to emphasize accuracy of response at the cost of responding more slowly seems to allow them to maintain the same level of cue-driven performance as their hearing peers. In the third study I focused on partial hearing loss. Little is known on the consequences of pure presbycusis, which is usually associated with aging (Age-related Hearing Loss, ARHL). In this case, auditory information is still present, although linked to an amount of uncertainty regarding its usefulness. In this study I started to investigate the role of ARHL on cognition considering covert orienting of attention, selective attention and executive control. I compared older adults with and without mild to moderate presbycusis (26-60 dB) performing 1) a spatial cueing task with uninformative central cues (social vs. non-social cues), 2) a flanker task and 3) a neuropsychological assessment of attention. Notably, while hearing impaired individuals responded as equally fast as their normally hearing peers, they were characterized by reduced validity effects on spatial cueing of attention, though no additional group differences were found between the impact of social and non-social cues. Hearing impaired individuals also demonstrated diminished performance on the Montreal Cognitive Assessment (MoCA) and on tasks requiring divided attention and flexibility. Conversely, overall response times and flanker interference effects were comparable across groups. This work indicates that while response speed and response inhibition appear to be preserved following mild to moderate presbycusis, orienting of attention, divided attention and the ability to flexibly allocate attention, are more deteriorated in older adults with ARHL. These findings suggest that presbycusis might exacerbate the detrimental influences of aging on visual attention. Taken together, the findings of my research project highlight the different role hearing loss may play at different life stages. On the one hand, congenital and early deafness seems to induce cognitive and behavioral compensations, which may encompass oculomotor behavior as well; these changes occur progressively during development and may reflect experience-dependent plasticity. On the other hand, late-life compensations in vision and visual attention in older adults with presbycusis may not take place or do not effectively reduce the negative impact of the auditory impairment. Rather, my data suggest that in this population a deficit in audition may consequently lead to a deficit in visual attention. Future lines of research can aim to better characterize other aspects of attention in the aging population with presbycusis, e.g. peripheral visual attention and the relationship between covert and overt attention. Finally, future research may also consider intervention through early diagnosis and treatment by means of hearing aids, which can be beneficial to cognitive functions and might delay or even prevent cognitive decline in this population, in which sensory compensation may not be sufficient.