Hierarchies of Self-Organizing Maps for action recognition

We propose a hierarchical neural architecture able to recognise observed human actions. Each layer in the architecture represents increasingly complex human activity features. The first layer consists of a SOM which performs dimensionality reduction and clustering of the feature space. It represents the dynamics of the stream of posture frames in action sequences as activity trajectories over time. The second layer in the hierarchy consists of another SOM which clusters the activity trajectories of the first-layer SOM and learns to represent action prototypes. The third- and last-layer of the hierarchy consists of a neural network that learns to label action prototypes of the second-layer SOM and is independent – to certain extent – of the camera’s angle and relative distance to the actor. The experiments were carried out with encouraging results with action movies taken from the INRIA 4D repository. In terms of representational accuracy, measured as the recognition rate over the training set, the architecture exhibits 100% accuracy indicating that actions with overlapping patterns of activity can be correctly discriminated. On the other hand, the architecture exhibits 53% recognition rate when presented with the same actions interpreted and performed by a different actor. Experiments on actions captured from different view points revealed a robustness of our system to camera rotation. Indeed, recognition accuracy was comparable to the single viewpoint case. To further assess the performance of the system we have also devised a behavioural experiments in which humans were asked to recognise the same set of actions, captured from different points of view. Results form such a behavioural study let us argue that our architecture is a good candidate as cognitive model of human action recognition, as architectural results are comparable to those observed in humans.     

Predicting Change in Parenting Stress Across Early Childhood: Child and Maternal Factors

This study examined maternal parenting stress in a sample of 430 boys and girls including those at risk for externalizing behavior problems. Children and their mothers were assessed when the children were ages 2, 4, and 5. Hierarchical linear modeling (HLM) was used to examine stability of parenting stress across early childhood and to examine child and maternal factors predicting parenting stress at age 2 and changes in parenting stress across time. Results indicated that single parenthood, maternal psychopathology, child anger proneness, and child emotion dysregulation predicted 2-year parenting stress. Child externalizing behaviors predicted initial status and changes across time in parenting stress. Stability of parenting stress was dependent upon child externalizing problems, as well as interactions between child externalizing problems and gender, and child externalizing problems and emotion regulation. Results are discussed in the context of mechanisms by which parenting stress may influence the development of child externalizing behaviors.     

Hierarchical Model of Generalized and Specific Vulnerabilities in Anxiety

This study evaluated a theoretical hierarchical relationship among the general anxiety vulnerability variable of neuroticism, the specific vulnerability variables of anxiety sensitivity and intolerance of uncertainty, and variables reflecting specific anxiety foci including panic symptoms, health anxiety, obsessive-compulsive symptoms and generalized anxiety/worry. Questionnaires assessing these variables were administered to a non-clinical sample of 91 first-year psychology students (64.8% women). Path analysis results were highly consistent with the hypothesized hierarchical model. Neuroticism was found to have a significant direct effect on both anxiety sensitivity and intolerance of uncertainty. Both neuroticism and anxiety sensitivity had direct significant effects on panic symptoms, neuroticism and intolerance of uncertainty both made significant direct contributions to the prediction of worry, and neuroticism made a significant direct contribution to the prediction of obsessive-compulsive symptoms. Contrary to the hypothesized model, anxiety sensitivity but not neuroticism uniquely predicted health anxiety. The results of this study provide initial empirical evidence for a hierarchical relationship among general and specific vulnerabilities, and specific anxiety manifestations.     

Does visual working memory work as a few fixed slots?

The present study investigated whether visual working memory (VWM) functions as a few (about 3?～ 4) fixed slots by examining how the distribution of VWM is adjusted. Adopting a change-detection paradigm, we required subjects to memorize four items, one of which was prioritized. If VWM functions as 3?～?4 slots, allocating multiple slots to the prioritized item would leave no slot for some other items; consequently no information would be stored for them, leading to a substantial decrease in change-detection performance no matter whether small or large changes occurred. The result showed that small changes on the unfavoured items were detected less accurately, indicating that more VWM was allocated to the favoured item. Yet meanwhile large changes that occurred on those unfavoured items could still be detected as well as those on the favoured one, indicating that each of them was still stored to some extent rather than completely discarded. The results suggested that VWM may not work as 3?～?4 fixed slots. Possible mechanisms were discussed based on the present results, including a modified slot model with more available slots, a continuous resource model, and a hierarchical model that assumes storage of ensemble information in addition to the information of individual items.     

Spouses' Cortisol Associations and Moderators: Testing Physiological Synchrony and Connectedness in Everyday Life

In this study, associations were examined between cortisol levels of wives and husbands in 47 heterosexual married couples. Both partners' salivary cortisol levels were measured at the same moments seven times a day on 2 typical weekdays. After accounting for the effects of the diurnal rhythm of cortisol and relevant control variables, dyadic hierarchical linear modeling indicated significant positive linkages between partners' cortisol levels, consistent with the hypothesized within‐couple physiological synchrony. Variables reflecting more (spousal presence) or less connectedness (loneliness, being alone) were also collected at the time of each cortisol sample. Results indicated that husbands' cortisol levels were higher at moments they reported feeling lonelier and lower at moments they were in the presence of their spouse. Wives' cortisol levels were higher at moments they were alone. In addition, wife–husband cortisol synchrony was stronger for husbands who spent relatively more time with their spouse across the study period—even after accounting for time spent with others in general. These findings suggest that marital partners evidence positive within‐couple cortisol associations, and that connectedness (particularly physical closeness) may underpin spouses' physiological synchrony.     

Peer Substance Use and Homelessness Predicting Substance Abuse from Adolescence Through Early Adulthood

Adolescents who experience homelessness are at higher risk for abusing substances, and for being exposed to substance-using peers. The current study used a longitudinal design to track substance abuse, affiliation with substance-using peers, and episodes of homelessness among a sample of 223 adolescents who were housed at the baseline data collection and 148 adolescents who were housed at baseline. Participants were interviewed at six waves over 6.5 years, covering an age range from 13 to 25. Many participants experienced a recurrence of homelessness during follow-up, with 64.6 % of the baseline homeless group and 22.6 % of the baseline housed group reporting an additional episode of homelessness. Both alcohol abuse and other drug abuse symptoms showed an increase in adolescence followed by slowing in early adulthood. Recent homelessness and friend alcohol use predicted alcohol abuse symptoms, and the strength of the influence of friend use decreased over time. Recent homelessness and friend drug use predicted other drug abuse symptoms. Duration of the initial episode of adolescent homelessness showed no influence on substance abuse over time, or the effects of other predictors, highlighting the importance of conceptualizing the experience of homelessness as a recent stressor rather than an enduring personal characteristic.     

Information-Hierarchical Organization of Natural Systems I: The Information-Physical Principle

The mathematical notion of information characterizing system organization as such has been developed. The information-physical principle, which characterizes an information exchange in natural hierarchical systems and has been confirmed by its numerous applications, is laid down. It is shown to be based on the ancient “matter–measure–information” concept of physical world structure and talked about in the Hermes Trismegistus's will.     

Hierarchical structure of the Eysenck Personality Inventory in a large population sample: Goldberg’s trait-tier mapping procedure

The structure of the Eysenck Personality Inventory (EPI) is poorly understood, and applications have mostly been confined to the broad Neuroticism, Extraversion and Lie scales. Using a hierarchical factoring procedure, we mapped the sequential differentiation of EPI scales from broad, molar factors to more specific, molecular factors, in a UK population sample of over 6500 persons. Replicable facets at the lowest tier of Neuroticism included oversensitivity, mood lability, nervous tension and rumination. The lowest order set of replicable Extraversion facets consisted of social dynamism, sociotropy, haste, jocularity, communalism and impulsivity. The Lie scale consisted of an interpersonal virtue and a behavioral diligence facet. Users of the EPI may be well served in some circumstances by considering its broad Neuroticism, Extraversion and Lie scales as multifactorial, a feature that was explicitly incorporated into subsequent Eysenck inventories and is consistent with other hierarchical trait structures.     

Youth belonging and cognitive engagement in organized activities: A large-scale field study

Numerous studies of organized activities have found that participation is associated with a range of positive outcomes; however, findings from recent randomized trials have been more mixed. Understanding youth's psychological experiences of program involvement – their cognitive and emotional reaction to and participation in activities – may be key to understanding the influence of organized activities. Hierarchical linear modeling was used to investigate correlates of youth belonging and cognitive engagement in a sample of 1160 youth in 123 program offerings in 66 sites. Results revealed that intensity (frequency) of exposure positively predicted belonging and cognitive engagement; however, duration was negatively associated with cognitive engagement. The staff practice of providing a welcoming atmosphere predicted belonging; whereas provision of active skill-building predicted cognitive engagement. These relations were found to vary across content type.