The Role of Randomization in Bayesian and Frequentist Design of Clinical Trial

A key role in inference is played by randomization, which has been extensively used in clinical trials designs. Randomization is primarily intended to prevent the source of bias in treatment allocation by producing comparable groups. In the frequentist framework of inference, randomization allows also for the use of probability theory to express the likelihood of chance as a source for the difference of end outcome. In the Bayesian framework, its role is more nuanced. The Bayesian analysis of clinical trials can afford a valid rationale for selective controls, pointing out a more limited role for randomization than it is generally accorded. This paper is aimed to offer a view of randomization from the perspective of both frequentist and Bayesian statistics and discussing the role of randomization also in theoretical decision models.

     

Global/local processing of hierarchical visual stimuli in a conflict–choice task by capuchin monkeys (<Emphasis Type="Italic">Sapajus</Emphasis> spp.)

In the last two decades, comparative research has addressed the issue of how the global and local levels of structure of visual stimuli are processed by different species, using Navon-type hierarchical figures, i.e. smaller local elements that form larger global configurations. Determining whether or not the variety of procedures adopted to test different species with hierarchical figures are equivalent is of crucial importance to ensure comparability of results. Among non-human species, global/local processing has been extensively studied in tufted capuchin monkeys using matching-to-sample tasks with hierarchical patterns. Local dominance has emerged consistently in these New World primates. In the present study, we assessed capuchins’ processing of hierarchical stimuli with a method frequently adopted in studies of global/local processing in non-primate species: the conflict–choice task. Different from the matching-to-sample procedure, this task involved processing local and global information retained in long-term memory. Capuchins were trained to discriminate between consistent hierarchical stimuli (similar global and local shape) and then tested with inconsistent hierarchical stimuli (different global and local shapes). We found that capuchins preferred the hierarchical stimuli featuring the correct local elements rather than those with the correct global configuration. This finding confirms that capuchins’ local dominance, typically observed using matching-to-sample procedures, is also expressed as a local preference in the conflict–choice task. Our study adds to the growing body of comparative studies on visual grouping functions by demonstrating that the methods most frequently used in the literature on global/local processing produce analogous results irrespective of extent of the involvement of memory processes.     

The attentional cost of inattentional blindness

When our attention is engaged in a visual task, we can be blind to events which would otherwise not be missed. In three experiments, 97 out of the 165 observers performing a visual attention task failed to notice an unexpected, irrelevant object moving across the display. Surprisingly, this object significantly lowered accuracy in the primary task when, and only when, it failed to reach awareness. We suggest that an unexpected stimulus causes a state of alert that would normally generate an attentional shift; if this response is prevented by an attention-consuming task, a portion of the attentional resources remains allocated to the object. Such a portion is large enough to disturb performance, but not so large that the object can be recognized as task-irrelevant and accordingly ignored. Our findings have one counterintuitive implication: irrelevant stimuli might hamper some types of performance only when perceived subliminally.     

Mother-child emotional availability in ecological perspective: three countries, two regions, two genders

This study used a cross-national framework to examine country, region, and gender differences in emotional availability (EA), a prominent index of mutual socioemotional adaptation in the parent-child dyad. Altogether 220 Argentine, Italian, and U.S. mothers and their daughters and sons from both rural and metropolitan areas took part in home observations when the children were 20 months old. In terms of country, Italian mothers were more sensitive and optimally structuring, and Italian children were more responsive and involving, than Argentine and U.S. dyads. In terms of region, rural mothers were more intrusive than metropolitan mothers, and boys from metropolitan areas were more responsive than boys from rural areas. In terms of gender, mothers of girls were more sensitive and optimally structuring than mothers of boys, and daughters were more responsive and involving than sons. Understanding how country, region, and gender influence EA exposes forces that shape child development, parent-infant interaction, and family systems.     

Parental bonding and personality disorder: the mediating role of alexithymia

This study explored whether alexithymic features mediate the effect of perceived adverse parenting during childhood on being diagnosed with a PD in adulthood. Two hundred sixty-five psychiatric outpatients were evaluated with the Toronto Alexithymia Scale (TAS-20), the Parental Bonding Instrument (PBI), the Structured Interview for DSM-IV Personality, the Structured Clinical Interview for DSM-IV Axis I Disorders, the Clinical Global Impression scale, and the Global Assessment of Functioning scale. The statistical model for mediation proposed by Baron and Kenny (1986) was employed to detect whether the TAS scores account for the relation between PBI scores and a PD diagnosis. The results indicated that although altered parental bonding (and specifically, excessive maternal protection) may enhance the risk of PD, its effect is completely mediated by the alexithymic feature Difficulty Describing Feelings to Others (DDF), after controlling for gender, age, educational level, type, severity and age of onset of Axis I disorders. Therefore, this study suggests that the presence of DDF accounts for the effect of maternal overprotection as a risk factor for PD.     

Maternal aggression toward infanticidal males of different social status in wild house mice (Mus musculus domesticus)

Maternal aggression was examined in wild female mice (Mus musculus domesticus) derived from animals trapped in Alberta, Canada. Lactating females were tested for their behavior toward intruder males during the time of postpartum estrus while housed in a two-cage apparatus containing a defensible nest area. Prior to being used as intruders, sexually naive males were screened for their behavior toward a newborn pup (83% exhibited infanticide). Only infanticidal males were then housed in pairs and allowed to establish a dominance hierarchy. Dominance status was further verified by a urine marking test. The dominant and subordinate infanticidal males were then placed into a lactating female's cage and observed for 1 hr. The test was terminated immediately when a male began to attack the pups. Lactating females attacked the males in both groups, but subordinate males received more intense attacks than dominant males. Dominant males elicited significantly more fear/defense behavior than subordinate intruders. All of the dominant males and only one submissive male attacked the pups. Females were thus successful in blocking infanticide only by infanticidal subordinate males. Since females do not persist in attacking males with high fighting ability, one function of maternal aggression could be to assess the fighting, and resource holding, potential of a future mate. © 1994 Wiley-Liss, Inc.     

Adult attachment styles and psychological disease: examining the mediating role of personality traits

The aim of the present study was to examine differences in anxiety and depression related to differences in attachment models of the self and of others and whether personality traits mediate this relationship. The authors assessed attachment styles, anxiety, depression, and personality traits among 274 adult volunteers. Participants were classified into 4 attachment groups (secure, preoccupied, fearful, and dismissing-avoidant) according to K. Bartholomew's (1990) model. The present authors found significant differences among attachment groups on anxiety and depressive symptoms with attachment styles involving a negative self-model showing higher scores than attachment styles characterized by a positive self-model. The authors also found that differences between attachment styles in anxiety and depression remained significant when personality factors related to attachment prototypes were entered as covariates. Results indicate that secure attachment in adults was associated with better mental health, while insecure attachment styles characterized by negative thinking about the self were associated with higher depression and anxiety scores. Our findings seem to evidence that attachment and personality are only partly overlapping and that attachment cannot be considered as redundant with personality in the explanation of psychological disease.     

Identifying the Creative Act in Advertising: A Study on Naïve People's Awareness of Restructuring

This study investigates whether laypersons can distinguish between creative and non-creative artifacts, identify when creativity emerges, and be aware of the merit to be attributed to those who conceive a creative idea. Study 1 analyzed a creative and a non-creative version of two advertisements. In the creative version, there was an ideational process of advertising drafts where the first meaning changed, whereas in the non-creative version the original meaning did not change. Forty undergraduates were asked to judge beauty and originality of each draft and the contribution that graphics managers gave to the outcome. Non-creative changes did not affect beauty and originality ratings, whereas creative modifications increased originality, but not beauty score. Merit was attributed to the graphics manager who transformed the original meaning. In Study 2, one hundred twenty-eight participants evaluated four combinations of textual (creative/noncreative) and iconic (creative/non-creative) elements which were added to the advertisements. Again, the creative, but not the non-creative, contribution to drafts was acknowledged regarding originality by participants. Findings suggest that people can recognize the presence of creativity when it develops and the restructuring mechanism that supports it.     

Verbal and Nonverbal Anticipatory Mechanisms in Bilinguals

Empirical evidence collected so far has revealed that the bilingual advantage cannot be reduced to a single component of the executive functioning, and point to the need to understand the effects of bilingual experience on cognition as influencing a wider family of mental processes, including, but not limited to, cognitive control. The present study aims to explore a relatively underinvestigated domain of bilingual cognitive processes, namely anticipation, through a series of different paradigms tapping proactive and reactive mechanisms at different levels of cognitive complexity and linguistic components. The sample included 25 adult bilinguals (\(26.5\, \pm \,7.8\) years) and 25 monolinguals (\(26.4\, \pm \, 7\) years) matched for age, gender, and non-verbal IQ. Participants were administered two experimental tasks: Attentional Network Task (ANT), and auditory picture-word identification task. Compared to monolinguals, bilinguals showed overall faster reaction times and reduced conflict effect on both the ANT and the picture-word identification task. In addition, associations between performances in the nonverbal and the verbal tasks support the role of the nonverbal monitoring component on verbal anticipation. Results are discussed in light of a dynamic interaction between proactive and reactive mechanisms of cognitive control.     

Facial expressions and the ability to recognize emotions from the eyes or mouth: A comparison among old adults,young adults,and children

The aim of the present study was to contribute to the literature on the ability to recognize anger, happiness, fear, surprise, sadness, disgust, and neutral emotions from facial information (whole face, eye region, mouth region). More specifically, the aim was to investigate older adults' performance in emotions recognition using the same tool used in the previous studies on children and adults’ performance and verify if the pattern of emotions recognition show differences compared with the other two groups. Results showed that happiness is among the easiest emotions to recognize while the disgust is always among the most difficult emotions to recognize for older adults. The findings seem to indicate that is more easily recognizing emotions when pictures represent the whole face; compared with the specific region (eye and mouth regions), older participants seems to recognize more easily emotions when the mouth region is presented. In general, the results of the study did not detect a decay in the ability to recognize emotions from the face, eyes, or mouth. The performance of the old adults is statistically worse than the other two groups in only a few cases: in anger and disgust recognition from the whole face; in anger recognition from the eye region; and in disgust, fear, and neutral emotion recognition from mouth region.