Cerebral blood flow differences between long-term meditators and non-meditators

We have studied a number of long-term meditators in previous studies. The purpose of this study was to determine if there are differences in baseline brain function of experienced meditators compared to non-meditators. All subjects were recruited as part of an ongoing study of different meditation practices. We evaluated 12 advanced meditators and 14 non-meditators with cerebral blood flow (CBF) SPECT imaging at rest. Images were analyzed with both region of interest and statistical parametric mapping. The CBF of long-term meditators was significantly higher (p < .05) compared to non-meditators in the prefrontal cortex, parietal cortex, thalamus, putamen, caudate, and midbrain. There was also a significant difference in the thalamic laterality with long-term meditators having greater asymmetry. The observed changes associated with long-term meditation appear in structures that underlie the attention network and also those that relate to emotion and autonomic function.     

The mindful eye: Smooth pursuit and saccadic eye movements in meditators and non-meditators

BackgroundThis study examined the effects of cultivated (i.e. developed through training) and dispositional (trait) mindfulness on smooth pursuit (SPEM) and antisaccade (AS) tasks known to engage the fronto-parietal network implicated in attentional and motion detection processes, and the fronto-striatal network implicated in cognitive control, respectively.MethodsSixty healthy men (19–59 years), of whom 30 were experienced mindfulness practitioners and 30 meditation-naïve, underwent infrared oculographic assessment of SPEM and AS performance. Trait mindfulness was assessed using the self-report Five Facet Mindfulness Questionnaire (FFMQ).ResultsMeditators, relative to meditation-naïve individuals, made significantly fewer catch-up and anticipatory saccades during the SPEM task, and had significantly lower intra-individual variability in gain and spatial error during the AS task. No SPEM or AS measure correlated significantly with FFMQ scores in meditation-naïve individuals.ConclusionsCultivated, but not dispositional, mindfulness is associated with improved attention and sensorimotor control as indexed by SPEM and AS tasks.     

Visual sensitivity and mindfulness meditation

Practitioners of the mindfulness form of Buddhist meditation were tested for visual sensitivity before and immediately after a 3-mo. retreat during which they practiced mindfulness meditation for 16 hr. each day. A control group composed of the staff at the retreat center was similarly tested. Visual sensitivity was defined in two ways: by a detection threshold based on the duration of simple light flashes and a discrimination threshold based on the interval between successive simple light flashes. All light flashes were presented tachistoscopically and were of fixed luminance. After the retreat, practitioners could detect shorter single-light flashes and required a shorter interval to differentiate between successive flashes correctly. The control group did not change on either measure. Phenomenological reports indicate that mindfulness practice enables practitioners to become aware of some of the usually preattentive processes involved in visual detection. The results support the statements found in Buddhist texts on meditation concerning the changes in perception encountered during the practice of mindfulness.     

Emotional-vulnerability and mindfulness: a preliminary test of associations among negative affectivity, anxiety sensitivity, and mindfulness skills

This study evaluated associations between general (negative affectivity) and specific (anxiety sensitivity) factors that may relate to the mindfulness skill domains assessed by the Kentucky Inventory of Mindfulness Skills. Participants were 154 young adults (88 females; M(age) = 22.4 years, SD = 7.9) recruited from the community. Partially consistent with predictions, higher levels of negative affectivity were significantly associated with lower levels of Awareness, Acceptance, and Describe mindfulness skills, and higher levels of anxiety sensitivity were significantly associated with lower levels of Awareness and Acceptance mindfulness skills. Additionally, negative affectivity and anxiety sensitivity each demonstrated unique relations to participants' ability to experience the present state without evaluating or judging its content (Accept factor), after accounting for their shared variance, but only anxiety sensitivity demonstrated a unique association to the Act with Awareness factor independent of variance explained by negative affectivity. Findings are discussed in relation to theory and research on mindfulness processes.     

Attention and sensitivity in visual search

Summary In continuous visual search, targets can be detected within a certain area around the fixation point (control area). Recent observations have suggested that these areas are asymmetrical in their vertical extent, i.e., that targets can be detected at greater distances below than above the fixation point. In order to obtain more direct evidence on this asymmetry, two experiments were conducted using a contingent-display technique. Pronounced asymmetry of the vertical detection span was observed. A model is presented according to which the asymmetry results from the superposition of two sources: the permanent distribution of sensitivity and the actual distribution of attention along the vertical axis of the visual field. The detectability of a target at a given location is a joint function of the strength of these two factors at that location.     

Physiological anxiety responses in transcendental meditators and nonmeditators

In Exp. I, the spontaneous GSR of seven Transcendental Meditators and seven nonmeditators was measured in a sequence of five conditions: stress (shock avoidance)--rest--meditation (meditators) or rest/eyes closed (nonmeditators)--stress (shock avoidance)--rest. In Exp. II, the spontaneous GSR of a similar group of subjects was measured in a sequence of three conditions: rest--meditation or rest/eyes closed--rest. Analysis of variance did not yield significant differences between meditators and nonmeditators although analysis did verify that the shock-avoidance task effectively produced anxiety. It was concluded that Transcendental Meditation is not an effective means of reducing autonomic responses to stress under the present testing conditions.     

Individual Differences in visual imagery and spatial ability

Spatial ability is generally assumed to involve construction, transformation, and interpretation of mental images. To explore the relationship between spatial ability and both image quality and image process efficiency, 79 subjects performed eight spatial tests, completed three imagery questionnaires, and participated in six laboratory tasks. These laboratory tasks were devised to measure image quality and the efficiency of image generation, image rotation, image scanning, adding and subtracting detail in images, and integration of images. Although ratings of imagery control and vividness were unrelated to spatial test performance, laboratory measures of process efficiency and image quality were strongly related to spatial test performance and weakly related to one another. A structural equation model identified a single spatial factor, Visualization ability, that can be decomposed into unique variance plus a linear combination of measures of image quality and image process efficiency. An interpretation of this model is that successful performance on spatial tests requires maintenance of a high-quality image and efficient image transformation and inspection processes.     

Processing fluency affects behavior more strongly among people higher in trait mindfulness

Processing fluency is the ease of processing information about a stimulus, which people can attribute to the experience of enjoyment. Despite consistent findings that processing fluency can affect self-reported judgments, little research has examined whether processing fluency or its interactions with personality traits can affect behavior. The current studies demonstrate that processing fluency is more likely to affect behavior among people higher in trait mindfulness. We manipulated processing fluency with rhyming versus nonrhyming maxims in Study 1 and with regulatory fit versus nonfit in Study 2. Participants higher in mindfulness showed a stronger positive effect for processing fluency on the dependent variable: the number of ideas they listed in a task they continued for as long as they enjoyed it.     

Knowledge alters visual contrast sensitivity

Research has shown that the visual system’s sensitivity to variations in luminance (visual contrast) within a particular area of the retina is affected in a bottom-up fashion by the ambient contrast levels in nearby regions. Specifically, changes in the ambient contrast in areas surrounding the target area alter the sensitivity to visual contrast within the target area. More recent research has shown that paying attention to the target or target area modulates contrast sensitivity, suggesting a top-down influence over contrast sensitivity that is mediated by attention. Here we report another form of top-down influence over contrast sensitivity that is unlikely to be mediated by attention. In particular, we show that knowledge and/or expectations about the levels of visual contrast that may appear in upcoming targets also affect how sensitive the observer is to the contrast in the target. This sort of knowledge-driven, top-down contrast sensitivity control could be used to preset the visual system’s contrast sensitivity to maximize discriminability and to protect contrast-sensitive processes from a contrast overload. Overall, our results suggest that existing models of contrast sensitivity might benefit from the inclusion of top-down control mechanisms.     

Orientation sensitivity in the peripheral visual field

Orientation sensitivity in the peripheral visual field has been tested in two tasks: (a) setting horizontal the orientation of a grating at various retinal eccentricities, and (b) matching the orientation of a peripherally viewed grating as close as possible to an oblique reference viewed foveally. Both performances fall off with increasing retinal eccentricity. Magnification of the stimulus optimizes peripheral performance. Peripheral performance, optimized by magnification, varies with retinal eccentricity. It approaches, but does not reach, the foveal value (tested by the same method) at 10 deg of eccentricity, and is much lower at 20 and 30 deg of eccentricity.     

Vibro-tactile and visual asynchronies: sensitivity and consistency

We investigated the consistency between tactually and visually designated empty time intervals. In a forced-choice discrimination task, participants judged whether the second of two intervals was shorter or longer than the first interval. Two pulses defined the intervals. The pulse was either a vibro-tactile burst presented to the fingertip, or a foveally presented white square. The comparisons were made for uni-modal and cross-modal intervals. We used four levels of standard interval durations in the range of 100- 800 ms. The results showed that tactile empty intervals must be 8.5% shorter to be perceived as long as visual intervals. This cross-modal bias is larger for small intervals and decreases with increasing standard intervals. The Weber fractions (the threshold divided by the standard interval) are 20% and are constant over the standard intervals. This indicates that the Weber law holds for the range of interval lengths tested. Furthermore, the Weber fractions are consistent over uni-modal and cross-modal comparisons, which indicates that there is no additional noise involved in the cross-modal comparisons.     

Differences between searching among objects and searching among holes

We report results from six experiments in which participants had to search for a "C" among "O" distractors. The search items were either holes or objects, defined by motion, contrast, or both. Our main findings were (1) it was easier to search among objects than to search among holes, and (2) the difference between search among objects and search among holes was primarily caused by grouping with the background. The data support the hypothesis that the shape of a hole is only available indirectly. We further note that, in our experiments, search performance for both holes and objects depended on the surface medium used to define the search items.     

Sound improves diminished visual temporal sensitivity in schizophrenia

Visual temporal processing and multisensory integration (MSI) of sound and vision were examined in individuals with schizophrenia using a visual temporal order judgment (TOJ) task. Compared to a non-psychiatric control group, persons with schizophrenia were less sensitive judging the temporal order of two successively presented visual stimuli. However, their sensitivity to visual temporal order improved as in the control group when two accessory sounds were added (temporal ventriloquism). These findings indicate that individuals with schizophrenia have diminished sensitivity to visual temporal order, but no deficits in the integration of low-level auditory and visual information.     

Bandpass characteristics of high-frequency sensitivity and visual experience in blindsight

Patient RP suffers a unilateral right homonymous quadrant anopia but demonstrates better than chance discrimination for stimuli presented in the blind field at temporal frequencies between 33 and 47 Hz (all significant at p < .05, binomial). Examination of her reports of visual experience during blind-field discrimination suggests a more complex picture in which experiences particular to correct discrimination are not found at low-mid-gamma frequencies, but are significantly more likely than average (76%, p < .001) at a lower frequency (22 Hz) at which blindsight is not observed. We believe that visual experience may serve to support blindsight if discrimination tasks are generally impaired at frequencies outside of the low-mid-gamma band. If this is so, although generally experienced as non-specific and unstructured light, the visual experience that accompanies discrimination performance must be based upon a neural representation which includes information on the visual features present in the stimulus.     

Runners and meditators: a comparison of personality profiles

Although both running and meditating have been considered as healthful and enlightening, no data have yet been published comparing the personality profiles of the two groups. A sample of 48 runners and 43 meditators, all males between the ages of 40 and 60, were given the Cattell 16 PF Test Profile and the results were compared. The meditators were significantly more assertive and enthusiastic than the runners. They also appear as Significantly less conscientious and controlled than the runners, as well as more experimenting and suspicious.     

Contrast sensitivity during horizontal visual pursuit: dynamic sensitivity functions.

The contrast sensitivity functions of college students for grating targets presented at angular velocities of 0, 30, 60, and 90 deg s-1 were determined for target durations of 200 and 600 ms. The most pronounced effects of target movement were evident at the mid to high spatial frequencies in which sensitivity was markedly reduced as velocity increased. These adverse effects were greatest in the 200 ms condition, in which performance was largely limited to the saccadic eye movement system. In the 600 ms condition, in which both saccadic and smooth pursuit eye movements were possible, contrast sensitivity for the low-frequency target actually improved significantly for the 30 and 60 deg s-1 targets, whereas only adverse effects of target motion were found for targets of mid and high spatial frequencies. The results are discussed in terms of the limitations of traditional visual assessment procedures and the practical and theoretical benefits of conceptualizing the joint effects of target composition and target movement.     

Speechreading skill and visual movement sensitivity are related in deaf speechreaders

Individual speechreading abilities have been linked with a range of cognitive and language-processing factors. The role of specifically visual abilities in relation to the processing of visible speech is less studied. Here we report that the detection of coherent visible motion in random-dot kinematogram displays is related to speechreading skill in deaf, but not in hearing, speechreaders. A control task requiring the detection of visual form showed no such relationship. Additionally, people born deaf were better speechreaders than hearing people on a new test of silent speechreading.     

Depression, low self-esteem and mindfulness

Negative biases in processing information about the self have long been recognised as a central feature in the development and maintenance of clinical depression. In practice, however, it may not be easy to distinguish between patients whose negative thinking about the self is primarily an aspect of current mood state, and those for whom it represents a reflection of more enduring issues (low self-esteem). The paper speculates that, in both cases, metacognitive awareness (acceptance of the idea that thoughts, assumptions and beliefs are mental events and processes rather than reflections of objective truth) may be an important precursor to active engagement in therapy on the part of the patient, and considers what aspects of cognitive therapy might be used to promote it in clinical practice.