On the Non-Existence of Optimal Solutions and the Occurrence of “Degeneracy” in the CANDECOMP/PARAFAC Model

The CANDECOMP/PARAFAC (CP) model decomposes a three-way array into a prespecified number of R factors and a residual array by minimizing the sum of squares of the latter. It is well known that an optimal solution for CP need not exist. We show that if an optimal CP solution does not exist, then any sequence of CP factors monotonically decreasing the CP criterion value to its infimum will exhibit the features of a so-called “degeneracy”. That is, the parameter matrices become nearly rank deficient and the Euclidean norm of some factors tends to infinity. We also show that the CP criterion function does attain its infimum if one of the parameter matrices is constrained to be column-wise orthonormal.     

Native language influences on word recognition in a second language: a megastudy

Many studies have reported that word recognition in a second language (L2) is affected by the native language (L1). However, little is known about the role of the specific language combination of the bilinguals. To investigate this issue, the authors administered a word identification task (progressive demasking) on 1,025 monosyllabic English (L2) words to native speakers of French, German, and Dutch. A regression approach was adopted, including a large number of within- and between-language variables as predictors. A substantial overlap of reaction time patterns was found across the groups of bilinguals, showing that word recognition results obtained for one group of bilinguals generalize to bilinguals with different mother tongues. Moreover, among the set of significant predictors, only one between-language variable was present (cognate status); all others reflected characteristics of the target language. Thus, although influences across languages exist, word recognition in L2 by proficient bilinguals is primarily determined by within-language factors, whereas cross-language effects appear to be limited. An additional comparison of the bilingual data with a native control group showed that there are subtle but significant differences between L1 and L2 processing.     

Women's meta-perceptions of attractiveness and their relations to body image

The present study examined meta-perceptions of attractiveness among women. More specifically, ratings were collected about how women thought their partner, family and friends, and strangers would view their physical attractiveness. In an online survey, 1287 Dutch women (aged 19-80 years) answered questions concerning meta-perceptions of attractiveness, demographic data, body mass index (BMI), body image (Body Areas Satisfaction Scale, self-rated general physical attractiveness, and actual-ideal weight discrepancy), and self-esteem. Results showed that women's meta-perceptions of attractiveness reflected the level of closeness of the relationship with the other person, with the most positive meta-perceptions reported for the partner, followed by those for family and friends, and the least positive meta-perceptions for strangers. Meta-perceptions were strongly related to body image, self-esteem and BMI. Self-ratings of attractiveness appeared to be lower than all meta-perceptions of attractiveness, suggesting that women are aware of their own negative self-bias and/or other people's positive bias.     

Social comparisons in the classroom: an investigation of the better than average effect among secondary school children

The better than average (BTA) effect refers to the tendency for the majority of people to rate themselves as being higher on positive attributes and lower on negative attributes than other people. The present study examined the occurrence of the BTA effect on five important characteristics among 15,806 first-year secondary school Dutch students. In addition, it explored the influence of students' gender, cultural background, and ability level on their evaluations of characteristics relative to their classmates. Results yielded small BTA effects, with the exception of the item “being eager to get high grades,” on which the effect was much larger. In addition, larger BTA effects were found among boys than girls, but this difference could not be attributed to actual differences in performance. Likewise, larger BTA effects were found among ethnic minority students from Turkish and Moroccan backgrounds than ethnic majority students, but this difference also could not be attributed to actual differences in performance. Theoretical and practical implications of these findings are discussed.     

An investigation into the impact of acute stress on encoding in older adults

Acute psychological stress commonly occurs in young and older adults’ lives. Though several studies have examined the influence of stress on how young adults learn new information, the present study is the first to directly examine these effects in older adults. Fifty older adults (M age = 71.9) were subjected to either stress induction or a control task before learning two types of information: a short video and a series of pictures. Twenty-four hours later, they were exposed to misleading information about the video and then completed memory tests for the video and pictures. Heart rate and cortisol measures suggest that a physiological stress response was successfully induced. Though pre-encoding stress had little impact on memory accuracy, stress did influence errors of omission on the cued recall test for the video. Findings are discussed in the context of previous research examining the effects of stress on memory in older adults.     

Postoperative Cognitive Dysfunction Versus Complaints: A Discrepancy in Long-Term Findings

This review describes the discrepancy in findings between postoperative cognitive performance and postoperative cognitive complaints long time after an operation under general anesthesia. Shortly (from 6 hr to 1 week) after an operation a decline in cognitive performance is reported in most studies. However, long time (from 3 weeks to 1–2 years) after an operation this is rarely found although some patients are still reporting cognitive complaints. In general this kind of research is suffering from severe methodological problems (use of insensitive tests, lack of control groups, lack of parallel tests, different definitions of cognitive decline). However, these problems cannot totally explain the discrepancy in findings in the long term. Thus, there are patients who have persistent cognitive complaints long time after an operation, that cannot be measured with cognitive tests. More psychological factors such as fixation on short-term cognitive dysfunction, mood, coping style, and personality are possible explanations for these cognitive complaints in the long term. As a consequence, these factors should be a topic in future research elucidating the persistence of these cognitive complaints long time after an operation under general anesthesia.     

Object pose: perceiving 3-d shape as sticks and slabs

Estimating the pose (three-dimensional orientation) of objects is an important aspect of 3-D shape perception. We studied the ability of observers to match the pose of the principal axes of an object with the pose of a cross consisting of three perpendicular axes. For objects, we used a long and a flat spheroid and eight symmetric objects with aspect ratios of dimensions of approximately 4:2:1. Stimulus cues were the contour and stereo for the spheroids, and contour, stereo, and shading for the symmetric objects. In addition, the spheroids were shown with or without surface texture and with or without active motion. Results show that observers can perform the task with standard deviations of a few degrees, though biases could be as large as 30 degrees. The results can be naturally decomposed in viewer-centered coordinates, and it turns out that the estimation of orientation in the frontoparallel plane (tilt) is more precise than estimation of orientation in depth (slant, roll). A comparison of long and flat spheroids shows that sticks lead to better performance than do slabs. This can even be the case within the same object; the pose of the stick-like aspect is seen with more precision than is the pose of the slab-like aspect. The largest biases occurred when the spheroids were displayed with the binocular contour as the only cue. We can explain these biases by assuming that subjects' settings are influenced by the orientation of the rim.     

Recognition of interlingual homophones in bilingual auditory word recognition

How do bilinguals recognize interlingual homophones? In a gating study, word identification and language membership decisions by Dutch-English bilinguals were delayed for interlingual homophones relative to monolingual controls. At the same time, participant judgments were sensitive to subphonemic cues. These findings suggest that auditory lexical access is language nonselective but is sensitive to language-specific characteristics of the input. In 2 cross-modal priming experiments, visual lexical decision times were shortest for monolingual controls preceded by their auditory equivalents. Response times to interlingual homophones accompanied by their corresponding auditory English or Dutch counterparts were also shorter than in unrelated conditions. However, they were longer than in the related monolingual control conditions, providing evidence for online competition of the 2 near-homophonic representations. Experiment 3 suggested that participants used sublexical cues to differentiate the 2 versions of a homophone after language nonselective access.     

Friendship Selection and Influence Processes for Physical Aggression and Prosociality: Differences between Single-Sex and Mixed-Sex Contexts

The present study examined to what extent selection and influence processes for physical aggression and prosociality in friendship networks differed between sex-specific contexts (i.e., all-male, all-female, and mixed-sex classrooms), while controlling for perceived popularity. Whereas selection processes reflect how behaviors shape friendships, influence processes reveal the reversed pattern by indicating how friends affect individual behaviors. Data were derived from a longitudinal sample of early adolescents from Chile. Four all-male classrooms (n = 150 male adolescents), four all-female classrooms (n = 190 female adolescents), and eight mixed-sex classrooms (n = 272 students) were followed one year from grades 5 to 6 (M _age = 13). Analyses were conducted by means of stochastic-actor-based modeling as implemented in RSIENA. Although it was expected that selection and influence effects for physical aggression and prosociality would vary by context, these effects showed remarkably similar trends across all-male, all-female, and mixed-sex classrooms, with physical aggression reducing and with prosociality increasing the number of nominations received as best friend in all-male and particularly all-female classrooms. Further, perceived popularity increased the number of friendship nominations received in all contexts. Influence processes were only found for perceived popularity, but not for physical aggression and prosociality in any of the three contexts. Together, these findings highlight the importance of both behaviors for friendship selection independent of sex-specific contexts, attenuating the implications of these gendered behaviors for peer relations.     

Body posture facilitates retrieval of autobiographical memories

We assessed potential facilitation of congruent body posture on access to and retention of autobiographical memories in younger and older adults. Response times were shorter when body positions during prompted retrieval of autobiographical events were similar to the body positions in the original events than when body position was incongruent. Free recall of the autobiographical events two weeks later was also better for congruent-posture than for incongruent-posture memories. The findings were similar for younger and older adults, except for the finding that free recall was more accurate in younger adults than in older adults in the congruent condition. We discuss these findings in the context of theories of embodied cognition.