The Change Processes in Selective Attention during Adulthood. Inhibition or Processing Speed?

Selective attention is involved in multiple daily activities. Several authors state that it experiences a decline after 20 years, although there is no agreement regarding the cognitive processes that explain it. Two theories dominate the discussion: The theory of inhibitory inefficiency and the theory of processing speed. At the same time, it has been suggested that there could be complementary relations between both; however, it is not clear what the contribution of inhibition and processing speed is on the changes of selective attention. Therefore, the present study proposes to analyze this contribution, in adults between 20 and 80 years old. To assess selective attention and inhibitory control, two indices of a visual search task were obtained in which participants must identify a target stimulus among a set of distracting stimuli. To evaluate the processing speed, a response speed task was used. The main results indicate that, from the age of 60, a gradual decrease in selective attention begins and that this decline can be largely explained by a decrease in processing speed and inhibitory control. We discuss about the literature on the development of selective attention, the contribution of processing speed, and the inhibitory inefficiency hypothesis.

Analysis of the effectiveness of using the block for limiting the vibrations of the load on the mechanism of movement of the bogie with various control systems

Damping load vibrations in an electric crane drive is an urgent topic for research. The swinging load has a negative effect on the mechanical part of the device, leading to its wear, and on the entire control system as a whole. To combat the swaying of the load, it is proposed to install a vibration damping block created on the basis of an equation describing the dependence of the change in the deviation of the load on the equilibrium position in the plane of movement of the cart. The control signals in the vibration damping unit are the parameters of truck acceleration, suspension length, and weight of the load. At the output of the vibration damping unit, a speed task is formed. A block diagram of the trolley drive control system has been developed. Both scalar systems and systems with direct torque control are used on trolley travel mechanisms. The paper analyzes the efficiency of using the vibration damping unit when using different control systems on the movement mechanism of the bridge crane trolley.

Altered Effective Connectivity during a Processing Speed Task in Individuals with Multiple Sclerosis

Objectives: Processing speed impairment is the most prevalent cognitive deficit in individuals with multiple sclerosis (MS). However, the neural mechanisms associated with processing speed remain under debate. The current investigation provides a dynamic representation of the functioning of the brain network involved in processing speed by examining effective connectivity pattern during a processing speed task in healthy adults and in MS individuals with and without processing speed impairment. Methods: Group assignment (processing speed impaired vs. intact) was based on participants’ performance on the Symbol Digit Modalities test (Parmenter, Testa, Schretlen, Weinstock-Guttman, & Benedict, 2010). First, brain regions involved in the processing speed task were determined in healthy participants. Time series from these functional regions of interest of each group of participants were then subjected to the effective connectivity analysis (Independent Multiple-Sample Greedy Equivalence Search and Linear, Non-Gaussian Orientation, Fixed Structure algorithms) that showed causal influences of one region on another during task performance. Results: The connectivity pattern of the processing speed impaired group was significantly different from the connectivity pattern of the processing speed intact group and of the healthy control group. Differences in the strength of common connections were also observed. Conclusions: Effective connectivity results reveal that MS individuals with processing speed impairment not only have connections that differ from healthy participants and MS individuals without processing speed impairment, but also have increased strengths of connections. (JINS, 2016, 22, 216–224)

Level of Recall, Retrieval Speed, and Variability on the Cued-Recall Retrieval Speed Task (CRRST) in Individuals with Amnestic Mild Cognitive Impairment

Individuals with amnestic mild cognitive impairment (aMCI) show deficits on traditional episodic memory tasks and reductions in speed of performance on reaction time tasks. We present results on a novel task, the Cued-Recall Retrieval Speed Task (CRRST), designed to simultaneously measure level and speed of retrieval. A total of 390 older adults (mean age, 80.2 years), learned 16 words based on corresponding categorical cues. In the retrieval phase, we measured accuracy (% correct) and retrieval speed/reaction time (RT; time from cue presentation to voice onset of a correct response) across 6 trials. Compared to healthy elderly adults (HEA, n = 303), those with aMCI (n = 87) exhibited poorer performance in retrieval speed (difference = −0.13; p < .0001) and accuracy on the first trial (difference = −0.19; p < .0001), and their rate of improvement in retrieval speed was slower over subsequent trials. Those with aMCI also had greater within-person variability in processing speed (variance ratio = 1.22; p = .0098) and greater between-person variability in accuracy (variance ratio = 2.08; p = .0001) relative to HEA. Results are discussed in relation to the possibility that computer-based measures of cued-learning and processing speed variability may facilitate early detection of dementia in at-risk older adults. (JINS, 2012, 18, 260–268)