Dementia praecox as a failure of neoteny

The theory of neoteny assumes that adult animals that are higher on the phylogenetic scale retain juvenile characteristics for greater periods of their lifetime. This hypothesis would account for the continuation of curiosity, learning and playfulness in humans and other higher primates in contrast to less evolved mammals. The failure of the neoteny process could result in humans that have lost these juvenile characteristics and lack motivation, curiosity and the capacity to learn freely. These features are indicative of the negative symptoms of dementia praecox, a chronic mental illness that strikes individuals as they become adults.It is postulated that a possible mechanism in the etiology of dementia praecox is the failure of regulator genes to program structural genes to produce enzymes necessary for neoteny. Positive symptoms of the disorder may be conceptualized as the organisms aberrant response to this activation failure. The role of regulator genes in chronic illness may prove a significant avenue for further investigation.     

Nature versus nurture: The simple contrast

We respond to the commentary of Franklin, Wright, and Davies (Journal of Experimental Child Psychology,102, 239-245 [2009]) by returning to the simple contrast between nature and nurture. We find no evidence from the toddler data that makes us revise our ideas that color categories are learned and never innate.     

Local and global processing: observations from a remote culture

In Experiment 1, a normal adult population drawn from a remote culture (Himba) in northern Namibia made similarity matches to [Navon, D. (1977). Forest before trees: The precedence of global features in visual perception. Cognitive Psychology, 9, 353-383] hierarchical figures. The Himba showed a local bias stronger than that has been previously observed in any other non-clinical human population. However, in Experiment 2, their recognition of normal or distorted ("Thatcherized") faces did not appear to have been affected by their attention to detail as has been suggested for autistic populations. The data are consistent with a cultural/experiential origin for population differences in local processing and suggest that attention to the local and global properties of stimuli may differ for hierarchical figures and faces.     

Patients suffering from nonspecific work-related upper extremity disorders exhibit insufficient movement strategies

The purpose of this research was to investigate whether patients experiencing nonspecific complaints of the forearm caused by sustained use of the personal computer exhibit deviant movement strategies as compared to healthy participants. Patients (N=10) and controls (N=24) performed a graphical aiming task combined with an auditory memory task. Force production (pen pressure), kinematic- and performance variables were recorded. During a trial, the control group gradually increased pen pressure from the stationary phases to the dynamic phase. The patients increased their pen pressure much more abruptly and to such a degree that the final pressure during real-time movement far exceeded that of the controls. Memory load led to a greater increase of pen pressure from the stationary phase to the dynamic phase in the patient group. Patients further displayed longer reaction times. The results are discussed within the framework of our recent theory on the role of neuromotor noise in the regulation of task performance under conditions of stress.     

Color categories: evidence for the cultural relativity hypothesis

The question of whether language affects our categorization of perceptual continua is of particular interest for the domain of color where constraints on categorization have been proposed both within the visual system and in the visual environment. Recent research (Roberson, Davies, & Davidoff, 2000; Roberson et al., in press) found substantial evidence of cognitive color differences between different language communities, but concerns remained as to how representative might be a tiny, extremely remote community. The present study replicates and extends previous findings using additional paradigms among a larger community in a different visual environment. Adult semi-nomadic tribesmen in Southern Africa carried out similarity judgments, short-term memory and long-term learning tasks. They showed different cognitive organization of color to both English and another language with the five color terms. Moreover, Categorical Perception effects were found to differ even between languages with broadly similar color categories. The results provide further evidence of the tight relationship between language and cognition.     

Constraints on decision making: Implications from genetics, personality, and addiction

An influential neurocomputational theory of the biological mechanisms of decision making, the “basal ganglia go/no-go model,” holds that individual variability in decision making is determined by differences in the makeup of a striatal system for approach and avoidance learning. The model has been tested empirically with the probabilistic selection task (PST), which determines whether individuals learn better from positive or negative feedback. In accordance with the model, in the present study we examined whether an individual’s ability to learn from positive and negative reinforcement can be predicted by genetic factors related to the midbrain dopamine system. We also asked whether psychiatric and personality factors related to substance dependence and dopamine affect PST performance. Although we found characteristics that predicted individual differences in approach versus avoidance learning, these observations were qualified by additional findings that appear inconsistent with the predictions of the go/no-go model. These results highlight a need for future research to validate the PST as a measure of basal ganglia reward learning.     

A standard for test reliability in group research

Many authors adhere to the rule that test reliabilities should be at least .70 or .80 in group research. This article introduces a new standard according to which reliabilities can be evaluated. This standard is based on the costs or time of the experiment and of administering the test. For example, if test administration costs are 7 % of the total experimental costs, the efficient value of the reliability is .93. If the actual reliability of a test is equal to this efficient reliability, the test size maximizes the statistical power of the experiment, given the costs. As a standard in experimental research, it is proposed that the reliability of the dependent variable be close to the efficient reliability. Adhering to this standard will enhance the statistical power and reduce the costs of experiments.     

The Prediction of Family Interaction from a Battery of Projective Techniques

This study first explored the adequacy of items on the Rorschach Rating Scale (RRS), which measures Rorschach constructs from a variety of scoring systems. Analyses determined that all items had an adequate capacity to differentiate people and none were clearly redundant. At the same time, the current version of the RRS requires good reading comprehension skills for accurate completion (13th grade level). Next, we developed two sets of RRS scales. Factor analysis of observer ratings (N = 234) indicated the RRS contained six broad, empirically derived factors. In addition, 19 conceptually derived scales were developed from the RRS item pool. Both sets of scales were evaluated for reliability and then compared to the Big Five model (B5M) of personality through a series of factor and regression analyses. Results indicated that RRS scales do not provide adequate definition of all B5M dimensions and B5M scales do not provide adequate definition of all RRS dimensions. We discuss the place of psychotic processes within a comprehensive model of personality and other implications from these findings.     

A 21st century cognitive portrait of the Himba,a remote people of Namibia

This research sketches the cognitive portrait of the Himba, a remote population from Northern Namibia living in a non-industrial society almost completely devoid of modern artefacts. We compared the Himba sample to a French sample, exploring cognitive reflection, moral judgement, cooperative behaviour, paranormal beliefs, and happiness. We looked for both differences and similarities across cultures, and for the way cognitive functioning is associated with a range of demographic variables. Results showed some important group differences, with the Himba being more intuitive, more religious, happier, and less utilitarian than the French participants. Further, the predictors of these beliefs and behaviours differed between the two groups. The present results provide additional support to the recent line of research targeting cultural variations and similarities, and call for the need to expand psychology research beyond the Western world.