Feedback and self-perception are often studied in relation to task performance as they are often associated with observable differences in performance. However, the way self-perception and feedback may affect each other and an individual has yet to be fully understood. Therefore, the purpose of this study is to determine whether there is a relationship between different types of feedback and subject self-perception, and to understand the effects of using different feedback types. A group of 39 young adults performed a series of amplitude discrimination tasks and were provided with three feedback conditions and completed a survey detailing their perception of their performance and the feedback provided. Results indicated that there is a difference in perception of feedback types, though there was no significant difference in performance between the feedback conditions. Additionally, there was some evidence that a pattern exists by which subjects with lower self-efficacy scores may be more susceptible to performance changes as feedback conditions change. These findings suggest that subjects are responsive to feedback, and that this responsivity could be related to subjects’ self-perception.
The objective of this study was to directly answer the practical question: how long lasting are the observed effects of pulsed electro-magnetic fields (PEMF) on seed germination? Earlier studies have shown that the effect of PEMF treatment on seed germination can be positive, neutral, or negative, exhibiting a tri-phasic inverse hormesis behavior as a function of total PEMF dosage during a single treatment session. This allows an optimal dosage range to be determined for maximum progerminative effect. Dosages in this range were found in earlier studies to increase the germination rate of pepper seeds to ~ 85%, from the baseline germination rate of ~56%, amounting to an increased germination rate of ~150% of baseline. One major practical consideration of this observation is whether the PEMF treatment is durable enough to allow central processing and long-term storage of the seeds for later use, or whether seeds treated by PEMF need to be planted shortly after treatment due to rapid loss of effect over time. If the latter, what is the allowable time between PEMF treatment and planting? In addition to their practical value, these observations will have considerable theoretical value as well. As the underlying biophysical mechanism of PEMF remains to be elucidated, quantitative assessments of the durability of the effect of PEMF treatment will give important clues as to the potential mechanisms involved; for example, whether they involve the activation of enzyme systems that remain activated or taper off, whether they initiate the release or activation of substances in reserve in the germ that are exhausted upon a single use, whether multiple mechanisms are involved as evidenced by multi-phasic decay over time, or whether the progerminative effect can be repeated more than one time in any given seed. For this study, the duration of the progerminative effect was measured by applying a previously-determined “optimal” dose of PEMF to pepper seeds, then storing the seeds in their original paper envelopes in a darkened room at 50% RH and room temperature for a period of up to one year post-treatment before planting, and determination of germination rate at two weeks (14 days). Finally, we study whether the lost progerminative effect can be recovered in stored seeds by reapplication of PEMF at the same dose immediately before planting. Our findings were that (1) the progerminative effect lasted only about 2 days after PEMF exposure, then returned about half way back to baseline and began a slow decline thereafter, but remained at approximately half-way, never returning to baseline even for periods of storage as long as 1 year, (2) a second application of PEMF restored almost all of the progerminative effect even after storage periods of up to one year. Storage periods longer than 1 year were not studied. These results add to the discussion of the mechanisms of PEMF across the span of complex organisms by suggesting the involvement of multiple mechanisms, some durable while others are semi-permanent.
The extent to which entrainment – the phenomenon in neuroscience where neurons synchronize their firing patterns to external stimuli with rhythmic or periodic features – occurs in response to aperiodic or irregular flutter stimuli remains debatable. It has been proposed by Mountcastle et al. that information is processed in a periodic manner; however, more recently, Romo et al. challenged Mountcastle’s theory and proposed that flutter stimulus was encoded based on the rapidly adapting fibers, not the periodicity.1-5 Therefore, if Mountcastle et al. is correct, the brain should be more adept at discriminating frequency between periodic stimuli than between aperiodic stimuli; conversely, if Romo et al. is correct, the brain should be equally good at discriminating frequencies between periodic and aperiodic stimuli. In this study, a two-point vibrotactile stimulation device (The Brain Gauge, Cortical Metrics, USA) was used to stimulate digits II and III of 43 participants’ preferred hand to determine their difference limen (DL) for both amplitude (AD) and frequency (FD) discrimination tests, given aperiodic or periodic stimuli. The tests were performed in the following order: periodic AD, aperiodic AD, periodic FD, and aperiodic FD. The results suggest that the periodicity of the stimuli affects frequency discrimination more than amplitude discrimination and the participants were significantly better at discriminating stimuli with periodic frequencies than aperiodic frequencies. A paired, one-tailed t-test indicated that the subject DLs resulting from periodic stimuli were significantly different (p<0.05) from that resulting from aperiodic stimuli for frequency discrimination, while it was not statistically significant for amplitude discrimination. The results were in favor of Mountcastle’s theory; however, more trials with a more controlled experimental environment may be needed to definitively conclude.
Past research has supported the idea that exercise is beneficial for the mind and cognitive functions. Further, imaging and neurotransmitter studies have shown how acute exercise can increase white matter and monoamines in the brain, thus improving cognition. On this basis, it was inferred that exercise, specifically long-term exercise, will improve an individual’s cognitive performance. To determine this, college-aged subjects were assessed with baseline reaction time and simultaneous amplitude discrimination tests. They subsequently participated in an acute exercise, after completing the same tests, to examine how their performance was affected. To evaluate fitness levels, subjects took a survey reporting their fitness levels and history, and their answers were translated into a comprehensive fitness score. In analyzing fitness score with test data, results concluded that those with more robust fitness levels performed better in the amplitude discrimination task. In addition, their reaction time variability, a consistent measure of cognitive focus, decreased (i.e., improved) following acute exercise. In contrast, those with lower fitness levels witnessed an increase in variability following exercise. This data suggests that taking part in exercise, particularly from a young age, can have long-term beneficial effects on cognitive function.
The goal of this study was to determine how human performance in discriminating between similar frequencies in the auditory spectrum was influenced by modifying the interstimulus interval (ISI). The ISI is defined as the time elapsed from the end of the first stimulus and the beginning of the second stimulus. The relationship between ISI and auditory discrimination was explored using an auditory file comprised of 40 tests that each contained two tones with a frequency difference of 1%. For each test, 44 participants were asked to select the tone they perceived as being a higher frequency. The two frequencies used in each test were centered around one of five base frequencies, and the ISI used in each test was one of eight predetermined intervals. Results from previous auditory frequency discrimination studies regarding the just-noticeable difference (JND) and Weber’s law were used in the selection of the frequency difference of 1% that was used in this experiment. This frequency difference was kept constant across all the tests in order to ensure that the ISI was the main factor influencing participant performance. Participant performance was greatest at an ISI of 1000 ms when results were averaged by frequency. Additionally, as the base frequency increased, average performance generally improved. The findings from this experiment promote further investigation into the effects of varying ISI on the integration of auditory information by the auditory cortex.
