Instructions as discriminative stimuli (2): A within‐subject examination of the effect of differential reinforcement on establishing novel instructional control1

Abstract: Six undergraduates were exposed to a fixed‐ratio schedule with an instruction to respond slowly and to a differential‐reinforcement‐of‐low‐rate schedule with an instruction to respond rapidly when a white circle was presented on a display monitor. When a yellow circle was presented, however, the subjects were exposed to the fixed‐ratio schedule with the instruction to respond rapidly and to the differential‐reinforcement‐of‐low‐rate schedule with the instruction to respond slowly. Following this, a fixed‐interval schedule was in effect during those stimuli and instructions. Under the white circle, response rates were higher with the instruction to respond slowly than with the instruction to respond rapidly during the fixed‐interval schedule. Such control by instructions was not observed under the yellow circle. A previous study examined establishment of novel instructional control by between‐subject comparisons and found that for three of four subjects ( Okouchi, 1999 ). In contrast, the present results demonstrate the instructional control through within‐subject comparisons for all six subjects.     

The influence of training task stimuli on transfer effects of working memory training in aging

IntroductionWorking memory (WM) training is known to produce benefits in older adults’ WM. Transfer effects to untrained abilities, however, remain controversial and several aspects are thought to influence the generalization of benefits, including the kind of stimuli used in the training tasks, an aspect rarely addressed in older adults.ObjectiveThe present study had two aims: (1) to test the efficacy of a visuospatial WM training procedure in older adults, in terms of specific and transfer effects; (2) to examine in two experiments whether the type of stimuli used in the training task influences the training's effectiveness. Experiment 1 adopted images with a neutral valence while experiment 2 used emotionally positive images based on evidence that older adults tend to remember positive stimuli better. In both experiments, specific training-related gains in a visuospatial WM task (the criterion task) and transfer effects on measures of verbal WM, visuospatial short-term memory, processing speed and reasoning were examined. Maintenance of training benefits was also assessed at an 8-month follow-up.MethodSeventy older adult (63–75 years old) volunteers (35 for experiment 1, and 35 for experiment 2) were randomly assigned to a training or active control group. The same visuospatial WM training procedure was used in both experiments, manipulating only the type of stimuli used (neutral in experiment 1 and emotionally positive in experiment 2).ResultsIn both experiments, only trained participants showed specific benefits in the WM criterion task. These gains were also maintained at the follow-up, but no transfer effects were identified.ConclusionOverall, our findings using the present visuospatial WM training paradigm suggest that it is less effective, in terms of transfer effects, than the same paradigm administered verbally in a previous study, regardless of the type of stimuli used in WM training tasks (neutral or emotionally positive stimuli).     

Spider-Phobic Children Do Not React with Differential Skin Conductance Responses to Masked Phobic Stimuli

In the present study, spider-phobic children (N = 22) were exposed to subliminal presentations of spiders, snakes, and mushrooms, while skin conductance responses (SCRs) were measured. In addition, pre- and post-treatment symptom severity data were obtained. As a group, spider-phobic children did not react with differential SCRs to masked phobic pictures. In addition, no convincing evidence was found to suggest that individual variation in differential SCRs to phobic stimuli is linked to pre-treatment symptom severity or therapy outcome. These findings cast doubts on the idea that phobics' phenomenal experience of their fear as irrational and uncontrollable is a result of pre-attentive physiological fear activation.     

Aging and sleep deprivation affect different neurocognitive stages of spatial information processing during a virtual driving task – An ERP study

We have previously shown that aging deteriorates detection of spatial visual and auditory stimuli and prolongs reaction times measured during a virtual driving task. Sleep deprivation affected the young more than the old. Here we determined the effects of age and sleep deprivation on ERPs elicited by spatial visual and auditory stimuli during virtual driving. Participants were 22 young (18–35 years) and 19 old (65–79) healthy males. Experiments were run in normal daytime condition and after a night of sleep deprivation. Aging shortened the peak latencies of the early P1 and N1 but increased the P3 latency. Sleep deprivation slowed down and diminished the N1 peaks of the young. General right-side preference was seen in latencies. Thus, the effects of aging could be seen in decision making and working memory related processes (P3), whereas those of sleep deprivation could be found in alerting and orienting functions (N1) in the young.