Perceptual strength is different from sensorimotor strength: Evidence from the centre–periphery asymmetry in masked priming

Near-threshold prime stimuli can facilitate or hinder responses to target stimuli, creating either a positive compatibility effect (PCE) or a negative compatibility effect (NCE). An asymmetry has been reported between primes presented in near periphery, which produced a PCE, and foveal primes, which produced an NCE under comparable conditions. This asymmetry has been attributed to the difference in retinal sensitivity, but it remains unclear whether this means that equating discrimination performance for primes in fovea and periphery, in order to account for differences in perceptual sensitivity, would make the priming effects the same. Wider work indicates that perceptual ability can dissociate from visuomotor effects, predicting that equating perceptual ability for fovea and periphery would not equate priming. We tested these opposite possibilities by matching discrimination performance for masked Gabor patches in fovea and near periphery (6°) and using these as primes in a masked priming paradigm expected to elicit NCEs. We found the asymmetry remained: NCE for fovea and PCE for periphery. We replicated this with both blocked and randomized procedures to check for attentional effects. We conclude that equating perceptual strength (discriminability) of stimuli does not equate their sensorimotor impact due to differences in the relative importance of different visual pathways and differing temporal dynamics in perceptual and sensorimotor processes.     

Community-driven learning activities,creating futures: 30,000 people can't be wrong—Can they?

A major vehicle for the practice of community psychology is through the organization of community-based activities. My colleagues and I have developed many programs for community learning centers, in-school and after school programs, and community technology centers. In the last 10 years, 30,000 people (mostly children) have participated in activities designed for enjoyment and learning, with a view to adding protective factors and reducing negative factors in at-risk communities. Development of these programs for literacy, education, life and work skills, has increasingly followed a community responsive model. Within each program, we created explicit images of future success. That is, people could see themselves being successful where they normally fail: self modeling with feedforward. Data reports show that individuals generalized and maintained their new skills and attitudes, but the sustainability of programs has been variable. Analysis of the variations indicates the importance of program level feedforward that brings the future into the present. The discussion includes consideration of how individual-level and community-level practices can inform each other. Author Note: Aspects of this article have been presented at the 10th Trans-Tasman Community Psychology Conference, Sydney, April 2006, and in an invited address at the 114th annual convention of the American Psychological Association, New Orleans, August 2006. Partial support in the preparation of this paper was provided by mutliple grants from the US Department of Education, although no endorsement is implied.     

Decision support for real-time, dynamic decision-making tasks

By definition, dynamic decision making dictates that multiple and interrelated decisions be made in a continuously changing environment. Such decision making is difficult and often taxes individuals’ cognitive resources. Here I investigated ways in which to support decision making in these environments. I evaluated three forms of decision support: outcome feedback, cognitive feedback, and feedforward that incorporated (to varying degrees) common features of learning theories associated with dynamic tasks. Participants in a laboratory experiment performed a real-time, dynamic decision-making task while receiving one of the different types of decision support. During the first 2 days, individuals received one type of decision support, but on the third day they performed the task without this support. Participants who received feedforward improved their performance considerably and continued to exhibit improved performance even after discontinuation of the decision support on the third day. Neither outcome feedback nor cognitive feedback resulted in improved performance. More research is necessary to conclusively identify the best forms of dynamic decision-making support and their durability when transferred to new tasks.     

TMS effects on subjective and objective measures of vision: stimulation intensity and pre- versus post-stimulus masking

Transcranial magnetic stimulation (TMS) can be used to mask visual stimuli, disrupting visual task performance or preventing visual awareness. While TMS masking studies generally fix stimulation intensity, we hypothesized that varying the intensity of TMS pulses in a masking paradigm might inform several ongoing debates concerning TMS disruption of vision as measured subjectively versus objectively, and pre-stimulus (forward) versus post-stimulus (backward) TMS masking. We here show that both pre-stimulus TMS pulses and post-stimulus TMS pulses could strongly mask visual stimuli. We found no dissociations between TMS effects on the subjective and objective measures of vision for any masking window or intensity, ruling out the option that TMS intensity levels determine whether dissociations between subjective and objective vision are obtained. For the post-stimulus time window particularly, we suggest that these data provide new constraints for (e.g. recurrent) models of vision and visual awareness. Finally, our data are in line with the idea that pre-stimulus masking operates differently from conventional post-stimulus masking.     

Using spotted hyena optimizer for training feedforward neural networks

Spotted hyena optimizer (SHO) is a novel metaheuristic optimization algorithm based on the behavior of spotted hyena and their collaborative behavior in nature. In this paper, we design a spotted hyena optimizer for training feedforward neural network (FNN), which is regarded as a challenging task since it is easy to fall into local optima. Our objective is to apply metaheuristic optimization algorithm to tackle this problem better than the mathematical and deterministic methods. In order to confirm that using SHO to train FNN is more effective, five classification datasets and three function-approximations are applied to benchmark the performance of the proposed method. The experimental results show that the proposed SHO algorithm for optimization FNN has the best comprehensive performance and has more outstanding performance than other the state-of-the-art metaheuristic algorithms in terms of the performance measures.     

Explorations of anticipatory behavioral control (ABC): a report from the cognitive psychology unit of the University of Würzburg

The report comprises recent theoretical considerations, experimental research, and simulations which all aim at a clarification of anticipatory mechanisms of behavioral control.     

Periodic change in phase relationship between target and hand motion during visuo-manual tracking task: Behavioral evidence for intermittent control

When one performs visuo-manual tracking tasks, velocity profile of hand movements shows discontinuous patterns even if the target moves smoothly. A crucial factor of this “intermittency” is considerable delay in the sensorimotor feedback loop, and several researchers have suggested that the cause is intermittent correction of motor commands. However, when and how the brain monitors task performance and updates motor commands in a continuous motor task is uncertain. We examined how tracking error was affected by the timing of target disappearance during a tracking task. Results showed that tracking error, defined as the average phase difference between target and hand, varied periodically in all conditions. Hand preceded target at one specific phase but followed it at another, implying that motor control was not performed in a temporally uniform manner. Tracking stability was evaluated by the variance in phase difference, and changed depending on the timing of target-removal. The variability was larger when target disappeared around turning points than that when it disappeared around the center of motion. This shows that visual information at turning points is more effectively exploited for motor control of sinusoidal target tracking, suggesting that our brain controls hand movements with intermittent reference to visual information.     

Motor adaptation and manual transfer: Insight into the persistent nature of sensorimotor representations

It is well known that sensorimotor memories are built and updated through experience with objects. These representations are useful to anticipatory and feedforward control processes that preset grip and load forces during lifting. When individuals lift objects with qualities that are not congruent with their memory-derived expectations, feedback processes adjust motor plans to achieve successful lifts and contribute to the updating of the stored representations. The two experiments presented examine motor adaptation to an illusory size–weight lifting task, and the transfer of this motor adaptation to the unexposed hand. In Experiment 1, performers acquired motor adaptation with their right hand and transfer was measured on their left hand. In Experiment 2, adaptation was acquired with the left hand and transfer was measured on the right hand. In order to investigate the persistence of sensorimotor memories, these experiments measure adaptation, retention, and transfer after 15 min and 24 h delay periods. Both experiments confirm that experience with objects leads to adaptation of force scaling processes, that these adaptations transcend effector and are persistent. The results are discussed in terms favouring interpretations that describe motor adaptations to illusion as being centrally available.