Speech monitoring skills in Alzheimer's disease, Parkinson's disease, and normal aging.

We examined the abilities of 15 patients with dementia of the Alzheimer type (DAT), 22 patients with Parkinson's Disease (PD), and 141 healthy subjects (ranging in age from 30 to 79 years) to detect and correct their own speech errors. Each subject was shown the Cookie Theft picture of the BDAE (Goodglass & Kaplan, 1972. The assessment of aphasia and related disorders. Philadelphia: Lea & Febiger.) and instructed to tell the examiner the "...story of what's happening in the picture." Self-monitoring performance was assessed by tabulating the number of uncorrected errors as well as repaired errors. We divided repairs into two types based on the psycholinguistics literature (van Wijk & Kempen, 1987. Cognitive Psychology, 19, 403-440). Speech corrections were judged to be lemma repairs when the reparandum was a single word, and reformulation repairs when a new syntactic constituent was added to the reparandum. Patients with DAT corrected only 24% of their total errors and patients with PD only 25%. Healthy subjects, by contrast, corrected from 72 to 92% of their total errors. Patients with DAT tended to rely on reformulation repairs while patients with PD used both repair types about equally often. While healthy elderly Ss (in the 70s group) utilized lemma repairs more often than the reformulation strategy, all other healthy Ss used both strategies about equally often. Across all groups naming performance correlated negatively with numbers of undetected errors. Results point to a previously unrecognized communication disorder associated with PD and DAT and manifested by an impairment in the ability to correct output errors. This impairment may be related to attentional and frontal dysfunction in the two patient groups.     

Research note: Peak velocity timing invariance

Summary Subjects used arm movements to move a dot on a visual display into a predefined target area. Measures of the peak velocity values and the timing of the peaks were taken for the initial (preplanned) and the immediately subsequent (corrective) phases of movement. In both phases the value of the maximum velocity depended on task parameters such as amplitude. However, the time of the peak of each phase relative to its onset was invariant. Some implications of these observations for the nature of motor programs are discussed.     

Effects of varying length of stimulus series and response scale upon response latency,response uncertainty,and transmitted information

A 3 by 3 orthogonal design was employed t o study the interrelations among response latency (RL), response uncertainty (E_R), and transmitted information Nine groups of Ss judged the size of 5, 20, or 40 projected squares in terms of 5, 20, or 40 response categories. Patterns of change in ER and RL over the three stimulus series were differentially effected by increases in the number of available response categories. The increase from 5 to 20 response categories produced, for successively longer stimulus series, a constantly increasing change in E_R; the further increase from 20 to 40 categories produced a contrasting, constantly decreasing change in E_R. The same two changes in number of response categories produced the same pattern of change in RL over the 5- and 20-stimulus series but reversed the pattern for the 40-stimulus series. Correlations between E_R and RL ranged from .28 to .99 and tended to maximize when number of response categories equaled the number of stimuli. I_t was relatively low under all conditions. Within the 5- and 20-stimulus series, increases from 5 to 20 to 40 available responses increased RL in a negatively accelerated fashion but did not increase I_t. Within the 40-stimulus series, the same increases in number of available responses produced an essentially linear increase in both I_t and RL.     

The nature of the association between diet and serum lipids in the community: a twin study.

Diet is commonly thought to be an environmental influence on serum lipid concentrations. This study evaluated whether total caloric and fat intake predict total cholesterol (TC), low-density lipoprotein cholesterol (LDL), high-density lipoprotein cholesterol (HDL), and triglyceride (TRIG) concentrations for environmental, as compared with genetic, reasons among 137 monozygotic and 67 dizygotic young adult twins. When genetic influences were controlled by correlating differences between monozygotic co-twins, a significant association remained between diet and TC, LDL, and HDL, suggesting that these dietary and serum lipid measures correlate for environmental reasons. Twin structural equation modeling confirmed these results. Overall, these results provide additional support for the hypothesis that diet is an environmental influence on TC, LDL, and HDL.