Ph.D., Birkbeck University of London, Psychology (2019)
M.S., UCL & Birkbeck University of London, Educational Neuroscience (2015)
M.S., University of Sheffield, Cognitive and Computational Neuroscience (2012)
B.S., University of Glasgow, Mathematics & Psychology (2011)
Tawna Roberts, Postdoctoral Faculty Sponsor
Validation of the PowerRef 3 for Measuring Accommodation: Comparison With the Grand Seiko WAM-5500A Autorefractor.
Translational vision science & technology
2022; 11 (10): 25
This validation study examines the PowerRef 3 as a method for measuring accommodation objectively. We assess agreement with refractive measurements obtained simultaneously by the Grand Seiko WAM-5500A autorefractor.Refractive measurements were recorded simultaneously using the PowerRef 3 and WAM-5500A in 32 noncyclopleged participants aged 15 to 46 years. Accommodative states were recorded for 10 seconds at six accommodative demands (5 diopters [D], 4 D, 3 D, 2.5 D, 2 D, and 0 D) while participants fixated a high-contrast Maltese cross. WAM-5500A measurements were converted to power in the vertical meridian for comparison with PowerRef 3 data. Dioptric difference values were computed, and agreement was assessed using Bland-Altman plots with 95% limits of agreement (LOA) and intraclass correlation coefficient analyses.The mean absolute dioptric differences measured 0.14 D or less across accommodative demands. Analyses showed an excellent intraclass correlation coefficient across the tested demands (0.93). Bland-Altman plots indicated a bias of -0.02 D with 95% LOA of -1.03 D to 0.99 D. The 95% LOA was smallest for the 3 D demand (-0.71 D to 0.64 D), and largest at 5 D demand (-1.51 D to 1.30 D).The mean dioptric differences between the PowerRef 3 and WAM-5500A autorefractor were small and not clinically significant. While some variability in agreement was observed depending on the tested demand, the PowerRef 3 demonstrated good agreement with the WAM-5500A.The PowerRef 3 may be used to obtain objective measures of accommodation both monocularly and binocularly and provides a more flexible method, especially in pediatric populations.
View details for DOI 10.1167/tvst.11.10.25
View details for PubMedID 36255360
Associations Between Distance Visual Acuity and Cycloplegic Refractive Error in Children Aged 5 to 9 Years
ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 2022
View details for Web of Science ID 000844401304104
Cultural differences in mutual gaze during face-to-face interactions: A dual head-mounted eye-tracking study
View details for DOI 10.1080/13506285.2021.1928354
View details for Web of Science ID 000652780600001
Early bilingual experience is associated with change detection ability in adults.
2021; 11 (1): 2068
To adapt to their more varied and unpredictable (language) environments, infants from bilingual homes may gather more information (sample more of their environment) by shifting their visual attention more frequently. However, it is not known whether this early adaptation is age-specific or lasts into adulthood. If the latter, we would expect to observe it in adults who acquired their second language early, not late, in life. Here we show that early bilingual adults are faster at disengaging attention to shift attention, and at noticing changes between visual stimuli, than late bilingual adults. In one experiment, participants were presented with the same two visual stimuli; one changed (almost imperceptibly), the other remained the same. Initially, participants looked at both stimuli equally; eventually, they fixated more on the changing stimulus. This shift in looking occurred in the early but not late bilinguals. It suggests that cognitive processes adapt to early bilingual experiences.
View details for DOI 10.1038/s41598-021-81545-5
View details for PubMedID 33483591
Cultural influences on face scanning are consistent across infancy and adulthood.
Infant behavior & development
2020; 61: 101503
The emergence of cultural differences in face scanning is thought to be shaped by social experience. However, previous studies mainly investigated eye movements of adults and little is known about early development. The current study recorded eye movements of British and Japanese infants (aged 10 and 16 months) and adults, who were presented with static and dynamic faces on screen. Cultural differences were observed across all age groups, with British participants exhibiting more mouth scanning, and Japanese individuals showing increased central face (nose) scanning for dynamic stimuli. Age-related influences independent of culture were also revealed, with a shift from eye to mouth scanning between 10 and 16 months, while adults distributed their gaze more flexibly. Against our prediction, no age-related increases in cultural differences were observed, suggesting the possibility that cultural differences are largely manifest by 10 months of age. Overall, the findings suggest that individuals adopt visual strategies in line with their cultural background from early in infancy, pointing to the development of a highly adaptive face processing system that is shaped by early sociocultural experience.
View details for DOI 10.1016/j.infbeh.2020.101503
View details for PubMedID 33190091
Affective priming enhances gaze cueing effect.
Journal of experimental psychology. Human perception and performance
Other's gaze direction triggers a reflexive shift of attention known as the gaze cueing effect. Fearful facial expressions are further reported to enhance the gaze cueing effect, but it remains unclear whether this facilitative effect is specific to gaze cues or the result of more general increase in attentional resources resulting from affective arousal. We examined the effects of affective priming on the cueing effects of gaze and arrow stimuli in the Posner cueing task. Participants were primed with two types of briefly presented affective stimuli (neutral, threatening), and the target location was cued either by an arrow or a gaze cue in a neutral face. Gaze cues were preceded by the same face with its eyes closed or directed to the viewer. Study 1 (n = 26) assessed the cueing effect using manual key press, and Study 2 (n = 30) employed gaze-contingent eye tracking techniques to assess the cueing effect using time to first fixate the cued target location. Both studies found that threatening priming significantly enhanced the cueing effects of eye gaze but not arrow stimuli. The results therefore suggest that affective priming does not facilitate general attentional orienting, but the facilitation is more specific to social cues such as eye gaze. (PsycInfo Database Record (c) 2020 APA, all rights reserved).
View details for DOI 10.1037/xhp0000880
View details for PubMedID 33166169
Is mere exposure enough? The effects of bilingual environments on infant cognitive development
ROYAL SOCIETY OPEN SCIENCE
2020; 7 (2): 180191
Bilinguals purportedly outperform monolinguals in non-verbal tasks of cognitive control (the 'bilingual advantage'). The most common explanation is that managing two languages during language production constantly draws upon, and thus strengthens, domain-general inhibitory mechanisms (Green 1998 Biling. Lang. Cogn.1, 67-81. (doi:10.1017/S1366728998000133)). However, this theory cannot explain why a bilingual advantage has been found in preverbal infants (Kovacs & Mehler 2009 Proc. Natl Acad. Sci. USA106, 6556-6560. (doi:10.1073/pnas.0811323106)). An alternative explanation is needed. We propose that exposure to more varied, less predictable (language) environments drive infants to sample more by placing less weight on consolidating familiar information in order to orient sooner to (and explore) new stimuli. To confirm the bilingual advantage in infants and test our proposal, we administered four gaze-contingent eye-tracking tasks to seven- to nine-month-old infants who were being raised in either bilingual (n = 51) or monolingual (n = 51) homes. We could not replicate the finding by Kovacs and Mehler that bilingual but not monolingual infants inhibit learned behaviour (experiment 1). However, we found that infants exposed to bilingual environments do indeed explore more than those exposed to monolingual environments, by potentially disengaging attention faster from one stimulus in order to shift attention to another (experiment 3) and by switching attention more frequently between stimuli (experiment 4). These data suggest that experience-driven adaptations may indeed result in infants exposed to bilingual environments switching attention more frequently than infants exposed to a monolingual environment.
View details for DOI 10.1098/rsos.180191
View details for Web of Science ID 000518020200016
View details for PubMedID 32257297
View details for PubMedCentralID PMC7062077
Culture modulates face scanning during dyadic social interactions
2020; 10 (1): 1958
Recent studies have revealed significant cultural modulations on face scanning strategies, thereby challenging the notion of universality in face perception. Current findings are based on screen-based paradigms, which offer high degrees of experimental control, but lack critical characteristics common to social interactions (e.g., social presence, dynamic visual saliency), and complementary approaches are required. The current study used head-mounted eye tracking techniques to investigate the visual strategies for face scanning in British/Irish (in the UK) and Japanese adults (in Japan) who were engaged in dyadic social interactions with a local research assistant. We developed novel computational data pre-processing tools and data-driven analysis techniques based on Monte Carlo permutation testing. The results revealed significant cultural differences in face scanning during social interactions for the first time, with British/Irish participants showing increased mouth scanning and the Japanese group engaging in greater eye and central face looking. Both cultural groups further showed more face orienting during periods of listening relative to speaking, and during the introduction task compared to a storytelling game, thereby replicating previous studies testing Western populations. Altogether, these findings point to the significant role of postnatal social experience in specialised face perception and highlight the adaptive nature of the face processing system.
View details for DOI 10.1038/s41598-020-58802-0
View details for Web of Science ID 000559758600021
View details for PubMedID 32029826
View details for PubMedCentralID PMC7005015
Effect of methylphenidate on visual responses in the superior colliculus in the anaesthetised rat: Role of cortical activation
JOURNAL OF PSYCHOPHARMACOLOGY
2017; 31 (10): 1347–61
The mechanism of action of psychostimulant drugs in the treatment of Attention Deficit Hyperactivity Disorder is still largely unknown, although recent evidence suggests one possibility is that the drugs affect the superior colliculus (SC). We have previously demonstrated that systemically administered d-amphetamine attenuates/abolishes visual responses to wholefield light flashes in the superficial layers of the SC in anaesthetised rats, and the present study sought to extend this work to methylphenidate (MPH). Anaesthetised rats were administered MPH at a range of doses (or saline) and subjected to monocular wholefield light flashes at two intensities, juxta-threshold and super-threshold. In contrast to d-amphetamine, systemic MPH produced an enhancement of visual activity at both intensities. Methylphenidate was also found to produce activation of the cortical EEG in anaesthetised rats. Furthermore, cortical activation induced by electrical stimulation of the pons was found to enhance visual responses in superficial layers of the SC, and when MPH was paired with pontine-induced cortical activation, the response-enhancing effects of MPH were substantially attenuated. Taken together, the results suggest that the enhancement of visual responses in the superficial layers of the SC by MPH in the anaesthetised rat is an artefact of the drug's interaction with cortical arousal.
View details for DOI 10.1177/0269881117730661
View details for Web of Science ID 000412824100008
View details for PubMedID 28925314
A systematic review of physiological methods in rodent pharmacological MRI studies
2015; 232 (3): 489–99
Pharmacological magnetic resonance imaging (phMRI) provides an approach to study effects of drug challenges on brain processes. Elucidating mechanisms of drug action helps us to better understand the workings of neurotransmitter systems, map brain function or facilitate drug development. phMRI is increasingly used in preclinical research employing rodent models; however, data interpretation and integration are complicated by the use of different experimental approaches between laboratories. In particular, the effects of different anaesthetic regimes upon neuronal and haemodynamic processes and baseline physiology could be problematic.This paper investigates how differences in phMRI research methodologies are manifested and considers associated implications, placing particular emphasis on choice of anaesthetic regimes.A systematic review of rodent phMRI studies was conducted. Factors such as those describing anaesthetic regimes (e.g. agent, dosage) and parameters relating to physiological maintenance (e.g. ventilatory gases) and MRI method were recorded.We identified 126 eligible studies and found that the volatile agents isoflurane (43.7 %) and halothane (33.3 %) were most commonly used for anaesthesia, but dosage and mixture of ventilatory gases varied substantially between laboratories. Relevant physiological parameters were usually recorded, although 32 % of studies did not provide cardiovascular measures.Anaesthesia and animal preparation can influence phMRI data profoundly. The variation of anaesthetic type, dosage regime and ventilatory gases makes consolidation of research findings (e.g. within a specific neurotransmitter system) difficult. Standardisation of a small(er) number of preclinical phMRI research methodologies and/or increased consideration of approaches that do not require anaesthesia is necessary to address these challenges.
View details for DOI 10.1007/s00213-014-3855-0
View details for Web of Science ID 000348307000001
View details for PubMedID 25585682
View details for PubMedCentralID PMC4302233