Mapping and correcting the influence of gaze position on pupil size measurements

Pupil size is correlated with a wide variety of important cognitive variables and is increasingly being used by cognitive scientists. Pupil data can be recorded inexpensively and non-invasively by many commonly used video-based eye-tracking cameras. Despite the relative ease of data collection and increasing prevalence of pupil data in the cognitive literature, researchers often underestimate the methodological challenges associated with controlling for confounds that can result in misinterpretation of their data. One serious confound that is often not properly controlled is pupil foreshortening error (PFE)—the foreshortening of the pupil image as the eye rotates away from the camera. Here we systematically map PFE using an artificial eye model and then apply a geometric model correction. Three artificial eyes with different fixed pupil sizes were used to systematically measure changes in pupil size as a function of gaze position with a desktop EyeLink 1000 tracker. A grid-based map of pupil measurements was recorded with each artificial eye across three experimental layouts of the eye-tracking camera and display. Large, systematic deviations in pupil size were observed across all nine maps. The measured PFE was corrected by a geometric model that expressed the foreshortening of the pupil area as a function of the cosine of the angle between the eye-to-camera axis and the eye-to-stimulus axis. The model reduced the root mean squared error of pupil measurements by 82.5 % when the model parameters were pre-set to the physical layout dimensions, and by 97.5 % when they were optimized to fit the empirical error surface.     

Verbal memory deficits in children with less than 750 g birth weight.

Numerous studies have documented memory deficits in very low birthweight (VLBW, < 1500 g) children, yet we know little about the nature of these memory problems. To clarify memory sequelae and examine memory deficits in relation to the degree of low birth weight, we administered the California Verbal Learning Test-Children's Version (CVLT-C) to a regional sample of 57 < 750 g birthweight children and to groups of 53 750-1499 g birthweight children and 49 term-born controls. Group comparisons revealed significant differences between the < 750 g birthweight group and term-born children on measures of list learning, delayed recall, and inaccurate recall. In addition, the percentage improvement in correct recognitions relative to long-term delayed recall was greater in the < 750 g group than in the term-born controls. Similar differences were observed between VLBW children with and without abnormal neonatal cerebral ultrasounds (high- and low-risk groups). Differences in learning rate between the VLBW and term-born groups, and between high- and low-risk VLBW children, were evident even when vocabulary skill was covaried or when children with neurosensory deficits or IQ < 80 were excluded from analysis. The findings document deficits in verbal memory in the subset of VLBW children at greatest biological risk, and suggest that acquisition processes are selectively impaired.     

Generalization of Supermarket Shopping Skills for Individuals with Mild Intellectual Disabilities Using Stimulus Equivalence Training

The Psychological Record - We developed an intervention to promote generalization in an applied community setting. The intervention was derived primarily from experimental research examining...     

Securing Cisgendered Futures: Intersex Management under the “Disorders of Sex Development” Treatment Model

In this critical, feminist account of the management of intersex conditions under 2006’s controversial “Disorders of Sex Development” (DSD) treatment model, I argue that like the “Optimal Gender of Rearing” (OGR) treatment model it replaced, DSD aims at securing a cisgendered future for the intersex patient, referring to a normalized trajectory of development across the lifespan in which multiple sexed, gendered, and sexual characteristics remain in “coherent” alignment. I argue this by critically analyzing two ways that intersex management has changed between OGR and DSD: 1) regarding sex‐assignment recommendations for three patient populations and, 2) with the prenatal treatment of pregnant individuals at risk of conceiving a fetus with congenital adrenal hyperplasia with the steroid hormone dexamethasone. I conclude that like OGR before it, DSD also unjustifiably presumes that typical genitalia are necessary for cisgendered development. However, unlike OGR, it appeals to the empirically inadequate, theoretically suspect, and biologically determinist model of gender development known as brain‐organization theory. Given this, I conclude that the treatment of intersex people under DSD continues to be driven by problematically heterosexist and transphobic assumptions regarding the value and normalcy of cisgendered life, while practically and discursively constituting it as such.     

Genetic and environmental influences on early literacy skills across school grade contexts

Recent research suggests that the etiology of reading achievement can differ across environmental contexts. In the US, schools are commonly assigned grades (e.g. ‘A’, ‘B’) often interpreted to indicate school quality. This study explored differences in the etiology of early literacy skills for students based on these school grades. Participants included twins drawn from the Florida Twin Project on Reading (n = 1313 pairs) aged 4 to 10 years during the 2006–07 school year. Early literacy skills were assessed with DIBELS subtests: Oral Reading Fluency (ORF), Nonsense Word Fluency (NWF), Initial Sound Fluency (ISF), Letter Naming Fluency (LNF), and Phoneme Segmentation Fluency (PSF). School grade data were retrieved from the Florida Department of Education. Multi‐group analyses were conducted separately for subsamples defined by ‘A’ or ‘non‐A’ schools, controlling for school‐level socioeconomic status. Results indicated significant etiological differences on pre‐reading skills (ISF, LNF, and PSF), but not word‐level reading skills (ORF and NWF). There was a consistent trend of greater environmental influences on pre‐reading skills in non‐A schools, arguably representing ‘poorer’ environmental contexts than the A schools. Importantly, this is the case outside of resources linked with school‐level SES, indicating that something about the direct environment on pre‐reading skills in the non‐A school context is more variable than for A schools.