Fitts’ Law as a Function of System Dynamics and Target Uncertainty

Fitts’ law was found to hold for discrete movements executed by subjects controlling the velocity of a cursor with a control stick. The slope of movement time versus index of difficulty was approximately twice as large as for a comparable position control system. Target uncertainty also increased the slope of total time versus index of difficulty, and this effect is interpreted in terms of adaptive tuning of the human movement system.     

Sentence processing in Lewy body spectrum disorder: the role of working memory

Prior work has related sentence processing to executive deficits in non-demented patients with Parkinson's disease (PD). We extended this investigation to patients with dementia with Lewy bodies (DLB) and PD dementia (PDD) by examining grammatical and working memory components of sentence processing in the full range of patients with Lewy body spectrum disorder (LBSD). Thirty-three patients with LBSD were given a two-alternative, forced-choice sentence-picture matching task. Sentence type, working memory, and grammatical structure were systematically manipulated in the sentences. We found that patients with PDD and DLB were significantly impaired relative to non-demented PD patients and healthy controls. The deficit in PDD/DLB was most pronounced for sentences lengthened by the strategic placement of an additional prepositional phrase and for sentences with an additional proposition due to a center-embedded clause. However, there was no effect for subject-relative versus object-relative grammatical structure. An MRI voxel-based morphometry analysis in a subset of patients showed significant gray matter thinning in the frontal lobe bilaterally, and this extended to temporal, parietal and occipital regions. A regression analysis related sentence processing difficulty in LBSD to frontal neocortex, including inferior prefrontal, premotor, and dorsolateral prefrontal regions, as well as right superior temporal cortex. These findings are consistent with the hypothesis that patients with PDD and DLB have difficulty processing sentences with increased working memory demands and that this deficit is related in part to their frontal disease.     

Phosphorylation of mitogen-activated protein kinase in the medial prefrontal cortex and the amygdala following memory retrieval or forgetting in developing rats

We examined neuronal correlates of forgetting in rats by detection of phosphorylated mitogen-activated protein kinase (pMAPK) in the medial prefrontal cortex (mPFC) and amygdala. In Experiment 1, postnatal day (P)23 and P16 rats received paired noise CS-shock US presentations. When tested immediately after conditioning, P23 and P16 rats exhibited similar levels of conditioned fear; when tested after 2 days, however, P16 rats showed poor CS-elicited freezing relative to P23 rats. In Experiment 2, P16 and P23 rats received either paired or unpaired CS-US presentations, and then were tested 48 h later. Consistent with Experiment 1, P16 rats showed forgetting whereas P23 rats exhibited good retention at test. Additionally, unpaired groups showed poor CS-elicited freezing at test. Immunohistochemistry showed that P23 and P16 rats given paired presentations exhibited significant elevation of pMAPK-immunoreactive (ir) neurons in the amygdala compared to rats given unpaired presentations. That is, MAPK phosphorylation in the amygdala tracked learning history rather than behavioral performance at test. In contrast, only the P23-paired group showed an elevated number of pMAPK-ir neurons in mPFC, indicating that MAPK phosphorylation in the mPFC tracks memory expression. Different test-perfusion intervals were employed in Experiment 3, which showed that the developmental dissociation in the pMAPK-ir neurons observed in the mPFC in Experiment 2 was not due to age differences in the rate of phosphorylation of MAPK. These findings provide initial evidence suggesting that while the mPFC is involved in memory retrieval, MAPK phosphorylation in the amygdala may be a persisting neural signature of fear memory.     

Accuracy and repeatability of the Yale physical activity survey in assessing physical activity of older adults.

The purpose of this study was to extend the initial evaluation of the Yale Physical Activity Survey to assess physical activity in older adults. The survey yields three indicators of physical activity reflecting activities performed during a typical week of the previous month (Total Time, Total Energy Expenditure) and the past month (Total Activity Summary Index). Questionnaire validity was studied in 56 men and women, ages 56 to 86 years, by comparing the average of 3- or 7 day 24-hr. physical activity records (n=56), predicted maximal oxygen consumption (VO2 max) (n = 23) and the sum of three skinfold measurements. Two-week repeatability was estimated by calculating an intraclass coefficient using an analysis of variance with repeated measures. Spearman rhos were used to study questionnaire validity. Analysis showed the survey was easily administered and scored and exhibited moderate-to-good repeatability. For the first administration the Total Energy Expenditure Index was significantly associated with the physical activity diary (r = .27). On the second administration, correlations were significant for the physical activity diary with the Total Energy Expenditure Index (r = .30), the Total Activity Summary Index (r = .36), and the Total Time Index (r = .27), and for VO2 max and the Total Time Index (r = .49) and Total Activity Summary Index (r = .64). Relative to the criterion measures used in this study, some validity was evident for the second administration in this relatively active and healthy sample of older adults.     

The thematic apperception test: toward a standard measure of the big three motives

The application of the Thematic Apperception Test to the assessment of motives has been heralded as an important milestone in personality psychology. However, although this approach is well established, there is at present no standard battery of cues for measuring the Big Three motives (achievement, affiliation, power). Furthermore, the extent to which scoring subcategories contribute to overall motive scores has been neglected. Our research with students and managers examined the effectiveness of picture cues in eliciting motive imagery and the prevalence of scoring subcategories within each motive scoring system. Results from 2 data sets comprising 547 men and women suggested that there were 3 cues that should be retained for future research and that motive scoring systems could be refined through removal of redundant subcategories. Further research is needed to systematically investigate the effectiveness of a standard battery of cues and the validity of revised motive scoring systems.     

The equivalence of the Child Behavior Checklist/1 1/2-5 across parent race/ethnicity, income level, and language

This study examined the equivalence of the Child Behavior Checklist/1 1/2-5 (CBCL/1 1/2-5) in 682 parents of 2- to 4-year-old children stratified by parent race/ethnicity (African American, Latino, and non-Latino White), family income (low vs. middle-upper), and language version (Spanish vs. English). Externalizing Scale means differed by income and child gender. Internalizing Scale means differed by income and parent race/ethnicity. Differential item analyses showed that few items functioned differently by racial/ethnic, language, and income group. A confirmatory factor analysis demonstrated that the Externalizing Scale provided a good fit with the data across racial/ethnic and income groups. However, model fit was improved for the Internalizing Scale when factor weights were allowed to vary. Findings support the equivalence of the CBCL/1 1/2-5 when used with parents of low-income preschool children from African American and Latino backgrounds, although further study of the factor structure for the Internalizing Scale is recommended.     

Responses to olfactory stimuli in spotted hyenas (Crocuta crocuta): II. Discrimination of conspecific scent

Scent marking in spotted hyenas (Crocuta crocuta) includes the deposition of anal sac secretions, or "paste," and presumably advertises territorial ownership. To test whether captive hyenas classify and discriminate individuals using odor cues in paste, the authors conducted behavioral discrimination bioassays and recorded hyena investigation of paste extracted from various conspecific donors. In Experiment 1, subjects directed most investigative behavior toward scents from unfamiliar hyenas and members of the opposite sex. In Experiment 2, male hyenas discriminated between concurrent presentations of paste from various unfamiliar females in similar reproductive states. Thus, pasted scent marks convey information about the sex, familiarity, and even identity of conspecifics. Aside from territory maintenance, scent marking may also communicate information about individual sexual status.     

A jigsaw-puzzle imagery task for assessing active visuospatial processes in old and young people

Recent studies have suggested a theoretical distinction between active elaboration and passive storage in visuospatial working memory, but research with older adults has failed to demonstrate a differential preservation of these two abilities. The results are controversial, and the investigation of the active component has been inhibited by the absence of any appropriate experimental procedures. A new task was developed involving the mental reconstruction of pictures of objects from fragmented pieces, and this provides a useful procedure for exploring active visuospatial processing. Significant differences in terms of both correctness and response latency were obtained between young and older adults and between younger old and older old adults. Performance also varied with visual complexity, mental rotation, and processing load. It is concluded that this ecologically relevant procedure constitutes a very powerful, sensitive, and reliable tool for identifying individual differences in visuospatial working memory.     

Mr. Magoo’s mistake

Timothy Williamson has famously argued that the (KK) principle (roughly, that if one knows that p, then one knows that one knows that p) should be rejected. We analyze Williamson’s argument and show that its key premise is ambiguous, and that when it is properly stated this premise no longer supports the argument against (KK). After canvassing possible objections to our argument, we reflect upon some conclusions that suggest significant epistemological ramifications pertaining to the acquisition of knowledge from prior knowledge by deduction.