Age changes in the missing-letter effect revisited

When participants search for a target letter while reading, they make more omissions if the target letter is embedded in frequent function words than in less frequent content words. Reflecting developmental changes in component language and literacy skills, the size of this effect increases with age. With adults, the missing-letter effect is due to both word function and word frequency. With children, it is unclear whether the growing size of the missing-letter effect across development is due to a larger effect of word function, word frequency, or both because previous studies with children seeking to isolate the influence of word frequency and word function suffer from important methodological limitations. With these methodological limitations eliminated (Experiments 1 and 2), performance in a letter detection task was assessed for children in Grades 1, 2, 3, 4, and 7 as well as for undergraduate students. The results revealed that the influence of word function increases with age, whereas the effect of frequency is fairly stable across ages. Furthermore, normative predictability data collected in Experiment 3 revealed that third graders and undergraduate students were equally good at predicting function slots in a sentence.     

The role of the hippocampus in the retrieval of a spatial location

Based on computational models of the hippocampus, it has been suggested that a possible mechanism for memory retrieval is pattern completion, wherein an autoassociative network recalls previous patterns of activity given noisy or degraded cues. However, there are few behavioral data examining pattern completion per se in the hippocampus. Here, we present a study in which rats were tested on a spatial location retrieval paradigm, each trial of which consisted of a sample and choice phase. During the sample phase, rats were trained to displace an object in one of 15 possible locations to retrieve a food reward and return to the start-box on a cheeseboard maze. The object was then removed and the same location was re-baited for the choice phase. The rats' accuracy in returning to the correct location was recorded. On test trials, visual extramaze cues, vestibular cues, or both were manipulated to assess pattern completion in normal rats. Subjects were then randomly assigned to receive a cortical control, a sham, or a dorsal and ventral hippocampal lesion and were retested on the task. Control and unoperated rats were able to perform the task when visual extramaze or vestibular cues were reliable, but not when they were manipulated. Rats with hippocampal lesions were impaired in the baseline condition, as well as during all manipulations. These results support the hypothesis that the hippocampus supports the retrieval of a spatial location, possibly through a process of pattern completion.     

Update on the biology of seasonal affective disorder

The etiology and pathophysiology of seasonal affective disorder (SAD) has been linked to the seasons and to light since its first conceptualization. Aspects of SAD that make it particularly amenable to biological investigation include the predictable recurrent episodes, the rapid response to a nonpharmacologic treatment, the specific neurovegetative features, and the availability of rich animal models of seasonality. This paper reviews new findings for the major biological hypotheses for SAD, focusing on circadian rhythms, neurotransmitters, and molecular genetics. Integrative issues and future directions for the study of SAD, including the heuristic value of a dual-vulnerability hypothesis that conceptualizes seasonality as a dimensional construct and the importance of studying endophenotypes, will be discussed.     

Reversal of motor learning in the vestibulo-ocular reflex in the absence of visual input

Motor learning in the vestibulo-ocular reflex (VOR) and eyeblink conditioning use similar neural circuitry, and they may use similar cellular plasticity mechanisms. Classically conditioned eyeblink responses undergo extinction after prolonged exposure to the conditioned stimulus in the absence of the unconditioned stimulus. We investigated the possibility that a process similar to extinction may reverse learned changes in the VOR. We induced a learned alteration of the VOR response in rhesus monkeys using magnifying or miniaturizing goggles, which caused head movements to be accompanied by visual image motion. After learning, head movements in the absence of visual stimulation caused a loss of the learned eye movement response. When the learned gain was low, this reversal of learning occurred only when head movements were delivered, and not when the head was held stationary in the absence of visual input, suggesting that this reversal is mediated by an active, extinction-like process.     

Predictive validity of the Psychopathy Checklist: Youth Version for general and violent recidivism

Several authors have expressed concern regarding the use of youth psychopathy assessments in determinations of risk for general and violent offending. The Psychopathy Checklist: Youth Version (PCL:YV) was completed with 182 male adolescent offenders in this prospective study (average 14.5 month follow-up) of general and violent recidivism. Both a two-factor and three-factor model of the PCL:YV significantly predicted general and violent recidivism at a predictive accuracy ranging from 68 to 63%. However, regression analyses indicated these associations were explained primarily by behavioral psychopathic symptoms, rather than interpersonal or affective traits. Implications for the use of psychopathy assessments for risk during adolescence are discussed.     

Morphological family size in a morphologically rich language: the case of Finnish compared with Dutch and Hebrew

Finnish has a very productive morphology in which a stem can give rise to several thousand words. This study presents a visual lexical decision experiment addressing the processing consequences of the huge productivity of Finnish morphology. The authors observed that in Finnish words with larger morphological families elicited shorter response latencies. However, in contrast to Dutch and Hebrew, it is not the complete morphological family of a complex Finnish word that codetermines response latencies but only the subset of words directly derived from the complex word itself. Comparisons with parallel experiments using translation equivalents in Dutch and Hebrew showed substantial cross-language predictivity of family size between Finnish and Dutch but not between Finnish and Hebrew, reflecting the different ways in which the Hebrew and Finnish morphological systems contribute to the semantic organization of concepts in the mental lexicon.     

The effects of differential negative reinforcement of other behavior and noncontingent escape on compliance

The present study evaluated the effects of noncontingent escape and differential negative reinforcement of other behavior in reducing problem behaviors and increasing compliance in 2 children with disabilities. Results showed that both methods reduced problem behavior and increased compliance for both children.     

Conscientiousness, autonomy fit, and development: a longitudinal study

The authors examined employee development and its relationship with Conscientiousness and person-environment fit (in terms of needs and supplies of autonomy). They hypothesized that Conscientiousness would be positively associated with development but only when employees felt that the autonomy supplied by the organization did not fit their needs. In other words, whereas Conscientiousness could supply the dispositional resources for development, misfit was needed to create the need for development. The results supported the authors' predictions. Conscientiousness was positively related to development but only when employees were misfits with respect to autonomy. Employee involvement in development activities was then linked to subsequent fit.