Exploring the Limits of Peripheral Vision for the Control of Movement

The role played by peripheral visual information in the control of aiming movements is not fully understood, as is indicated by the conflicting results reported in the literature. In the present study, the authors tested and confirmed the hypothesis that the source of the conflict lies in the portion of the visual peripheral field that has been under scrutiny in the different studies. Participants (N = 60) moved a computer mouse from a fixed starting position to 1 of 3 targets under varied vision conditions. The portion of the peripheral visual field that best ensured directional accuracy of a sweeping movement was found to be located between 20° and 10° of visual angle, whereas the area found to favor directional accuracy of an aiming movement comprised 30° through 10° of visual angle.     

The Role of Scheduling in Learning Through Observation

In the 2 experiments reported in the present article, participants (N = 40, Experiment 1; N = 60, Experiment 2) learned to solve complex puzzles under different schedules of physical practice, observation, or a combination of the two. The results of both studies indicated that observation, in the absence of any physical practice, allows the development of an accurate but relatively nonfunctional cognitive representation. The data suggest that, even when the motor demands are minimal, the functional significance of the cognitive representation is not maximally realized until physical interaction with the task is possible. Thus, providing the participant with an interspersed practice schedule during acquisition enables that interaction to occur, thereby allowing the absolute number of physical practice trials to be reduced and replaced by observation trials, but leading to equivalent learning.     

Duration perception of emotional stimuli: Using evaluative conditioning to avoid sensory confounds

It has been found that emotional pictures are estimated to last longer than neutral ones. However, emotional and neutral stimuli often differ in their physical characteristics, too. Since this might also affect time perception, we present a method disentangling a possible confounding regarding the processing of physically different stimulus material. In the evaluative condition paradigm, participants, at first, learnt the association of neutral images with a certain Landolt ring and of emotional images with another Landolt ring with a different gap position. The conditioned Landolt rings were subsequently used in a temporal bisection task. In two experiments, the results revealed a temporal overestimation of Landolt rings conditioned with emotional pictures compared to neutral pictures showing that the temporal overestimation of emotional stimuli cannot be attributed to perceptual differences between neutral and emotional stimuli. The method provides the potential for investigating emotional effects on various perceptual processes.     

Visual control of manual aiming movements in 6- to 10-year-old children and adults

Recent results indicate that adults modulate their initial movement impulse toward a stationary visual target by processing visual afferent information. The authors investigated whether the mechanisms responsible for those modulations are already in place in young children or develop as the children grow older. Adults (n = 10) and 6-, 8- and 10-year-old children (ns = 6, 7, and 7, respectively) performed a video-aiming task while vision of the cursor they were moving was (acquisition) or was not (transfer) visible. The results indicated that within-participant variability of the initial impulse trajectory of the children's aiming movement leveled-off in acquisition between peak extent deceleration and the end of the initial impulse, whereas it increased linearly as movement unfolded in transfer. The results also indicated that children modulate their initial movement impulse when visual afferent information is available, although to a lesser extent than adults do, and strongly imply that contrary to past suggestions, the initial impulse of an aiming movement is not ballistic.     

The role of oculomotor information in the learning of sequential aiming movements

With their eyes initially on either the home, midline, or final end position, 30 participants practiced a 2-target aiming movement. After 120 acquisition trials, participants performed a retention test and were then transferred to each of the other 2 eye conditions. During acquisition, all groups improved over practice, but the home group showed the greatest improvement. The temporal improvement was most pronounced in the times spent after peak velocity. Retention and transfer tests indicated that participants performed best under eye-movement conditions that were the same as the 1 they had practiced in. There was also positive transfer of training between conditions in which the oculomotor information was similar. Thus, to optimize learning, one should practice under the same afferent and oculomotor conditions that will be required for the final performance.     

Cognitive slowing and learning of target detection skills in pre-demented subjects

Alzheimer's disease produces a generalized slowing of cognitive processing increasing with the progression of dementia. However little is known about this phenomenon in the pre-demented stages. Our purpose was to investigate cognitive slowing in pre-demented subjects and their ability to develop target detection skills while performing a cancellation task. The results on 16 pre-demented subjects and 32 matched controls show that cognitive slowing is already present 3 years before subjects fulfill dementia criteria, at a stage where errors are still not different between pre-demented and control subjects. Additionally, the two groups significantly improved their time performances all along the test suggesting that both groups including the pre-demented group were able to progressively acquire a target detection skill.     

Outcome measures for clinical drug trials in autism

This paper identifies instruments and measures that may be appropriate for randomized clinical trials in participants with autism spectrum disorders (ASDs). The Clinical Global Impressions scale was recommended for all randomized clinical trials. At this point, however, there is no "perfect" choice of outcome measure for core features of autism, although we will discuss five measures of potential utility. Several communication instruments are recommended, based in part on suitability across the age range. In trials where the intention is to alter core features of ASDs, adaptive behavior scales are also worthy of consideration. Several "behavior complexes" common to ASDs are identified, and instruments are recommended for assessment of these. Given the prevalence of cognitive impairment in ASDs, it is important to assess any cognitive effects, although cognitive data from ASD randomized clinical trials, thus far, are minimal. Guidance from trials in related pharmacologic areas and behavioral pharmacology may be helpful. We recommend routine elicitation of side effects, height and weight, vital signs, and (in the case of antipsychotics) extrapyramidal side-effects assessment. It is often appropriate to include laboratory tests and assessments for continence and sleep pattern.     

Phoneme monitoring in silent naming and perception in adults who stutter

The present study investigated phonological encoding skills in persons who stutter (PWS). Participants were 10 PWS (M = 31.8 years, S.D. = 5.9) matched for age, gender, and handedness with 12 persons who do not stutter (PNS) (M = 24.3 years, S.D. = 4.3). The groups were compared in a phoneme monitoring task performed during silent picture naming. The phonological complexity of the target items in the task was varied such that participants monitored either compound words or noun phrases. Performance in this task was compared to phoneme monitoring performed on aurally presented target words to investigate whether any differences observed in silent naming were also evident in perception. Analysis of the response time data, in milliseconds, indicated that PWS were significantly slower as compared to PNS in phoneme monitoring during silent naming; group differences were not obtained in the perception task. The groups were also comparable in the response time to phoneme monitoring within compound words and noun phrases in both silent naming and perception. The findings suggested that PWS were slower in the encoding of segmental, phonological units during silent naming. Furthermore, absence of such differences in perception ruled out a general monitoring deficit in PWS. Findings are interpreted within the context of the psycholinguistic theories of stuttering that postulate phonological encoding and/or monitoring as a causal variable in stuttering.

Educational objectives: As a result of this activity, the participant should: (1) describe relevant literature on phonological encoding skills in children and adults who stutter, (2) identify paradigms that can be used to investigate phonological processing in PWS, and (3) discuss the role of phonological encoding in speech production.     

Speech and nonspeech sequence skill learning in adults who stutter

Two studies compared the speech and nonspeech sequence skill learning of nine persons who stutter (PWS) and nine matched fluent speakers (PNS). Sequence skill learning was defined as a continuing process of stable improvement in speed and/or accuracy of sequencing performance over practice and was measured by comparing PWS's and PNS's performance curves of accuracy, reaction time, and sequence duration, as well as retention and transfer. In experiment one, participants completed a 30-trial finger tapping sequence and in experiment two, a 30-trial read-aloud sequence of nonsense syllables. Significant between-group differences were found in the speed of sequencing performance after practice, and on retention and transfer tests. These results partially supported the inference that PWS demonstrated differences in early stages of sequence skill learning compared to PNS. EDUCATIONAL OBJECTIVES: As a result of this activity the participant will be able to: (1) define skill learning and the important indicators of skill learning; (2) summarize the reviewed literature concerning the performance of PWS on speech and nonspeech sequencing tasks over practice; and (3) explain the implication of reaction time differences over practice between PWS and PNS.     

Influence of education on the pattern of cognitive deterioration in AD patients: the cognitive reserve hypothesis

The cognitive reserve hypothesis proposes that a high educational level could delay the clinical expression of Alzheimer's disease (AD) although neuropathologic changes develop in the brain. Therefore, some studies have reported that when the clinical signs of the disease emerge, high-educated patients may decline more rapidly than low-educated patients because the neuropathology is more advanced. However, these studies have only investigated the decline of global cognition or an isolated cognitive process. To study the differential deterioration pattern of several cognitive processes according to education, the performance of 20 AD patients with a high educational level and a low educational level were compared with the performance of 20 control subjects on a neuropsychological battery. The results showed that cognitive deterioration of AD patients is different according to education, although the global performance was similar in AD patients. The high-educated patients exhibited greater impairment of abstract thinking whereas the low-educated patients showed greater impairment of memory and attentional function. This confirms that some cognitive processes, such as abstract thinking, decline more rapidly in high-educated patients whereas others seem to evolve more slowly if compared to low-educated patients. In this latter case, high-educated patients may still benefit from cognitive reserve after the diagnosis of the dementia.