Noise-robust fixation detection in eye movement data: Identification by two-means clustering (I2MC)

Eye-tracking research in infants and older children has gained a lot of momentum over the last decades. Although eye-tracking research in these participant groups has become easier with the advance of the remote eye-tracker, this often comes at the cost of poorer data quality than in research with well-trained adults (Hessels, Andersson, Hooge, Nyström, & Kemner Infancy, 20, 601–633, 2015; Wass, Forssman, & Leppänen Infancy, 19, 427–460, 2014). Current fixation detection algorithms are not built for data from infants and young children. As a result, some researchers have even turned to hand correction of fixation detections (Saez de Urabain, Johnson, & Smith Behavior Research Methods, 47, 53–72, 2015). Here we introduce a fixation detection algorithm—identification by two-means clustering (I2MC)—built specifically for data across a wide range of noise levels and when periods of data loss may occur. We evaluated the I2MC algorithm against seven state-of-the-art event detection algorithms, and report that the I2MC algorithm’s output is the most robust to high noise and data loss levels. The algorithm is automatic, works offline, and is suitable for eye-tracking data recorded with remote or tower-mounted eye-trackers using static stimuli. In addition to application of the I2MC algorithm in eye-tracking research with infants, school children, and certain patient groups, the I2MC algorithm also may be useful when the noise and data loss levels are markedly different between trials, participants, or time points (e.g., longitudinal research).     

A secreted form of the beta-amyloid precursor protein (sAPP695) improves spatial recognition memory in OF1 mice

The beta-amyloid precursor protein (APP) plays a central role in Alzheimer's disease (AD) and appears to be a multifunctional protein. Secreted forms of APP (sAPP) have memory-enhancing effects in certain behavioral paradigms. To investigate sAPP's role in spatial memory processes, we adapted a spatial recognition task and evaluated (1) the performance of OF1 mice after massed training (single 15-min acquisition session) and distributed training (three 5-min acquisition sessions), (2) the decline of spatial recognition performance by introducing different delays (5min, 1, 3, and 24h) between the acquisition and retention phases, and (3) the effects of sAPP(695) on spatial recognition memory. In the present study, mice selectively reacted to a change in the spatial configuration of five objects. Indeed, 3min post-acquisition, mice performed similarly in the massed and distributed versions of the task, by re-exploring the two displaced objects only, whereas mice exposed to the same spatial configuration did not. Additionally, all mice did react to a novel object in a subsequent object recognition phase. Mice detected object displacements 5min, 1h, or 3h post-acquisition, but no more at a 24h-delay. Finally, mice treated with sAPP(695) intracerebroventricularly at a dose of 0.5pg/4microL/mouse, 20-min pre-acquisition or 5-min post-acquisition, still reacted to a spatial change in objects position 24h post-acquisition, in marked contrast to NaCl-treated mice. Our data demonstrate that sAPP(695) significantly improves a form of spatial memory, and confirms the hypothesis of an action of this protein on early memory processes.     

Selective visual attention for ugly and beautiful body parts in eating disorders

Body image disturbance is characteristic of eating disorders, and current treatments use body exposure to reduce bad body feelings. There is however little known about the cognitive effects of body exposure. In the present study, eye movement registration (electroculography) as a direct index of selective visual attention was used while eating symptomatic and normal control participants were exposed to digitalized pictures of their own body and control bodies. The data showed a decreased focus on their own 'beautiful' body parts in the high symptomatic participants, whereas inspection of their own 'ugly' body parts was given priority. In the normal control group a self-serving cognitive bias was found: they focused more on their own 'beautiful' body parts and less on their own 'ugly' body parts. When viewing other bodies the pattern was reversed: high symptom participants allocated their attention to the beautiful parts of other bodies, whereas normal controls concentrated on the ugly parts of the other bodies. From the present findings the hypothesis follows that a change in the processing of information might be needed for body exposure to be successful.     

Stability of attachment during the preschool period

Children's attachment patterns at early preschool age and 2 years later as well as factors related to stability-instability were examined in a diverse socioeconomic status French Canadian sample of 120 children. Attachment was assessed during 2 laboratory visits using separation-reunion procedures when the children were approximately 3.5 (J. Cassidy & R. S. Marvin, 1992) and 5.5 (M. Main & J. Cassidy, 1988) years old. Overall, stability of attachment, based on 4-way classification, was moderate (68%, k = .47, p = .01). Change from security to disorganization was associated with the most dramatic decline in interactive quality with mother, lowest marital satisfaction, and greatest likelihood of severe attachment-related family events, namely, loss and parental hospitalization. Families of children who changed from security to organized insecurity presented levels of caregiving and marital dissatisfaction that fell between those of stable secure children and secure children who changed toward disorganization.     

Aging effects on memory encoding in the frontal lobes

Functional magnetic resonance imaging (fMRI) was used to compare frontal-lobe activation in younger and older adults during encoding of words into memory. Participants made semantic or nonsemantic judgments about words. Younger adults exhibited greater activation for semantic relative to nonsemantic judgments in several regions, with the largest activation in the left inferior frontal gyrus. Older adults exhibited greater activation for semantic judgments in the same regions. but the extent of activation was reduced in left prefrontal regions. In older adults, there was a significant association between behavioral tests of declarative and working memory and extent of frontal activation. These results suggest that age-associated decreases in memory ability may be due to decreased frontal-lobe contributions to the initial encoding of experience.     

Premarital Sexual Debut in Emerging Adults of South Asian Descent: The Role of Parental Sexual Socialization and Sexual Attitudes

Ethnicity is an important factor in premarital sexual debut as norms regarding appropriate sexual conduct outside of marriage vary considerably across cultures. Emerging adults of South Asian descent living in Western societies are an important demographic group, yet little is known about the factors that contribute to variations in their premarital sexual debut. The goal of this study was to investigate the contributions of parental sexual socialization and attitudes toward premarital sexual behaviors to premarital sexual debut in emerging adults of South Asian descent. University students of South Asian descent (N = 87) aged 18–24 completed a questionnaire containing measures of parental attitudes toward premarital sexual behaviors, their own attitudes toward premarital sexual behaviors, and experience with oral sex and intercourse. Mediation analyses showed that perceptions of mothers’ as more permissive toward premarital sexual behaviors was associated with respondents reporting more permissive attitudes toward premarital sexual behaviors, which in turn was associated with a greater likelihood of having engaged in oral sex and intercourse. No significant effect was found for fathers. These findings suggest that parental sexual socialization may influence emerging adults of South Asian descent’s decision to engage in premarital sexual behaviors through the process of sexual attitudes formation.     

Parallel development of ERP and behavioural measurements of visual segmentation

Visual segmentation, a process in which elements are integrated into a form and segregated from the background, is known to differ from adults at infancy. The further developmental trajectory of this process, and of the underlying brain mechanisms, during childhood and adolescence is unknown. The aim of the study was to investigate the developmental trajectory of ERP reflections of visual segmentation, and to relate this to behavioural performance. One hundred and eleven typically developing children from 7 to 18 years of age were divided into six age groups. Each child performed two visual tasks. In a texture segmentation task, the difference in event‐related potential (ERP) response to homogeneous (no visual segmentation) and checkered stimuli (visual segmentation) was investigated. In addition, behavioural performance on integration of elements into contours was measured. Both behavioural and ERP measurements of visual segmentation differed from adults in 7–12 year‐old children. Behaviourally, young children were less able to integrate elements into a contour than older children. In addition, a developmental change was present in the ERP pattern evoked by homogeneous versus checkered stimuli. The largest differences in behaviour and ERPs were found between 7–8‐ and 9–10‐, and between 11–12‐ and 13–14‐year‐old children, indicating the strongest development between those age groups. Behavioural as well as ERP measurements at 13–14 years of age showed similar results to those of adults. These results reveal that visual segmentation continues to develop until early puberty. Only by 13–14 years of age, children do integrate and segregate visual information as adults do. These results can be interpreted in terms of functional connectivity within the visual cortex.     

Abstract reasoning and the interpretation of basic conditionals

Studies examining the interpretation that is given to if–then statementstypically use what are referred to as basic conditionals, which give contextless relations between two unrelated concrete terms (If the ball is blue, then the shape is square). However, there is some evidence that basic conditionals require a more abstract form of representation. In order to examine this, we presented participants with truth-table tasks involving either basic conditionals or conditionals referring to imaginary categories (If it is a bori, then it has red wings), and standard conditional inference tasks with abstract and familiar premises. As expected, fewer typical defective conditional interpretations were given to basic conditionals. In addition, partial correlations showed a unique relationship between the interpretation of basic conditionals and abstract inferential reasoning. Results suggest that people process basic conditionals as a form of abstract reasoning, and that the interpretation of conditionals must consider the semantic context.     

Suicide Intervention Skills and Related Factors in Community and Health Professionals

Health and community professionals have considerable exposure to suicidal people and need to be well skilled to deal with them. We assessed suicide intervention skills with a Dutch version of the SIRI in 980 health and community professionals and psychology students. Suicide intervention skills clearly differed among professional groups and were strongly related to experience, especially suicide‐specific experience. Some community professionals scored below acceptable levels on their ability to respond appropriately to suicidal people they encounter, and tended to overestimate their skills level. Training is therefore indicated for these groups, and may be useful to more highly experienced groups too.