396 research outputs found
Cultural Differences in Group Therapy: A Phenomenological Study of the Lived Embodied Experience of the Cultural Bump
Utilizing transcendental phenomenology, this study sought to better understand dance/movement therapists’ experiences of the culture bump phenomenon in the group therapy setting. Culture bumps are defined as moments in which two or more people enter a situation with different culturally-based expectations about customs, behavior, beliefs, communication styles, and other norms (Archer & Nickson, 2012). Data were collected using individual inperson semi-structured interviews with five Chicagoland dance/movement therapists who self identified as having experienced the phenomenon of the culture bump while in the group therapy setting. Data analysis was completed using Moustakas’ (1994) adaptation of the Stevick-Colaizzi-Keen method and resulted in five textural-structural themes that describe the experience of the phenomenon of the culture bump: a) elusory and complex in nature, b) at its essence, about a meeting of differing expectations, c) having a shifting/changing quality to it, d) inextricably tied to the participant’s own cultural context, and e) therapeutically important material. The participants’ experiences indicated culture bumps are a common occurrence in the group dance/movement therapy setting, and both their presence and the processing of them are breeding grounds for necessary conversations about cultural difference. 54 pages - submitted as an article to the American Journal of Dance Therapy in February of 2018 in a format that meets the criteria for that publication, and so is shorter than a standard thesis
Grouping based feature attribution in metacontrast masking
The visibility of a target can be strongly suppressed by metacontrast masking.
Still, some features of the target can be perceived within the mask. Usually,
these rare cases of feature mis-localizations are assumed to reflect errors of
the visual system. To the contrary, I will show that feature
"mis-localizations" in metacontrast masking follow rules of
motion grouping and, hence, should be viewed as part of a systematic feature
attribution process
What should a quantitative model of masking look like and why would we want it?
Quantitative models of backward masking appeared almost as soon as computing
technology was available to simulate them; and continued interest in masking has
lead to the development of new models. Despite this long history, the impact of
the models on the field has been limited because they have fundamental
shortcomings. This paper discusses these shortcomings and outlines what future
quantitative models should look like. It also discusses several issues about
modeling and how a model could be used by researchers to better explore masking
and other aspects of cognition
Spatial frequency processing and the prediction of reading ability: A preliminary investigation
Binding binding: Departure points for a different version of the perceptual retouch theory
In the perceptual retouch theory, masking and related microgenetic phenomena were
explained as a result of interaction between specific cortical representational
systems and the non-specific sub-cortical modulation system. Masking appears as
deprivation of sufficient modulation of the consciousness mechanism suffered by
the target-specific signals because of the temporal delay of non-specific
modulation (necessary for conscious representation), which explicates the
later-coming mask information instead of the already decayed target information.
The core of the model envisaged relative magnitudes of EPSPs of single cortical
cells driven by target and mask signals at the moment when the nonspecific,
presynaptic, excitatory input arrives from the thalamus. In the light of the
current evidence about the importance of synchronised activity of specific and
non-specific systems in generating consciousness, the retouch theory requires
perhaps a different view. This article presents some premises for modification
of the retouch theory, where instead of the cumulative presynaptic spike
activities and EPSPs of single cells, the oscillatory activity in the gamma
range of the participating systems is considered and shown to be consistent with
the basic ideas of the retouch theory. In this conceptualisation, O-binding
refers to specific encoding which is based on gamma-band synchronised
oscillations in the activity of specific cortical sensory modules that represent
features and objects; C-binding refers to the gamma-band oscillations in the
activity of the non-specific thalamic systems, which is necessary for the
O-binding based data to become consciously experienced
Visual masking and the dynamics of human perception, cognition, and consciousness A century of progress, a contemporary synthesis, and future directions
The 1990s, the “decade of the brain,” witnessed major advances in the study of
visual perception, cognition, and consciousness. Impressive techniques in
neurophysiology, neuroanatomy, neuropsychology, electrophysiology, psychophysics
and brain-imaging were developed to address how the nervous system transforms
and represents visual inputs. Many of these advances have dealt with the
steady-state properties of processing. To complement this “steady-state
approach,” more recent research emphasized the importance of dynamic aspects of
visual processing. Visual masking has been a paradigm of choice for more than a
century when it comes to the study of dynamic vision. A recent workshop
(http://lpsy.epfl.ch/VMworkshop/), held in Delmenhorst, Germany,
brought together an international group of researchers to present
state-of-the-art research on dynamic visual processing with a focus on visual
masking. This special issue presents peer-reviewed contributions by the workshop
participants and provides a contemporary synthesis of how visual masking can
inform the dynamics of human perception, cognition, and consciousness
Electrophysiological activation by masked primes: Independence of prime-related and target-related activities
Visual stimuli that are made invisible by metacontrast masking (primes) have a
marked influence on behavioral and psychophysiological measures such as reaction
time (RT) and the lateralized readiness potential (LRP). 4 experiments are
reported that shed light on the effects that masked primes have on the LRP.
Participants had a go-nogo task in which the prime was associated with 1 of 2
responses even if the target required participants to refrain from responding.
To analyze the electrophysiological responses, we computed the LRP and applied
an averaging method separating the activation due to the prime and the target.
The results demonstrated that (a) masked primes activate responses even in a
nogo situation, (b) this prime-related activation is independent of masking, (c)
and is also independent of whether prime and target require the same responses
(congruent condition) or different responses (incongruent condition)
A theory of moving form perception: Synergy between masking, perceptual grouping, and motion computation in retinotopic and non-retinotopic representations
Because object and self-motion are ubiquitous in natural viewing conditions,
understanding how the human visual system achieves a relatively clear perception
for moving objects is a fundamental problem in visual perception. Several
studies have shown that the visible persistence of a briefly presented
stationary stimulus is approximately 120 ms under normal viewing conditions.
Based on this duration of visible persistence, we would expect moving objects to
appear highly blurred. However, in human vision, objects in motion typically
appear relatively sharp and clear. We suggest that clarity of form in dynamic
viewing is achieved by a synergy between masking, perceptual grouping, and
motion computation across retinotopic and non-retinotopic representations. We
also argue that dissociations observed in masking are essential to create and
maintain this synergy
Temporal Integration of Movement: The Time-Course of Motion Streaks Revealed by Masking
Temporal integration in the visual system causes fast-moving objects to leave oriented ‘motion streaks’ in their wake, which could be used to facilitate motion direction perception. Temporal integration is thought to occur over 100 ms in early cortex, although this has never been tested for motion streaks. Here we compare the ability of fast-moving (‘streaky’) and slow-moving fields of dots to mask briefly flashed gratings either parallel or orthogonal to the motion trajectory. Gratings were presented at various asynchronies relative to motion onset (from to ms) to sample the time-course of the accumulating streaks. Predictions were that masking would be strongest for the fast parallel condition, and would be weak at early asynchronies and strengthen over time as integration rendered the translating dots more streaky and grating-like. The asynchrony where the masking function reached a plateau would correspond to the temporal integration period. As expected, fast-moving dots caused greater masking of parallel gratings than orthogonal gratings, and slow motion produced only modest masking of either grating orientation. Masking strength in the fast, parallel condition increased with time and reached a plateau after 77 ms, providing an estimate of the temporal integration period for mechanisms encoding motion streaks. Interestingly, the greater masking by fast motion of parallel compared with orthogonal gratings first reached significance at 48 ms before motion onset, indicating an effect of backward masking by motion streaks
Onset Rivalry: Brief Presentation Isolates an Early Independent Phase of Perceptual Competition
When the left and right eyes are simultaneously presented with different images, observers typically report exclusive awareness of only one image. This phenomenon is termed binocular rivalry, reflecting the fact that the dominant image alternates every few seconds in a cycle of perceptual competition that continues indefinitely. Despite the apparent continuity in perceptual switching, we now demonstrate that the initial “onset” period is fundamentally different to all subsequent rivalry epochs. Using brief intermittent presentations, rivalry dominance shows strong biases such that the same target is perceived with each successive stimulus onset. These biases remain consistent within any given location, but vary across the visual field in a distribution that is stable over multiple weeks but highly idiosyncratic across observers. If the presentation exceeds ∼1sec at any location, however, the very different and much more balanced alternations of sustained binocular rivalry become apparent. These powerful onset biases are observed with brief intermittent presentations at a single location or with continual smooth motion of the targets. Periods of adaptation to one of the rivaling targets induced local switches in dominance to the non-adapted target. However, these effects were generally limited to the spatial site of adaptation and had less influence over each subsequent cycle of the target. We conclude that onset rivalry is independent of sustained rivalry and cannot be explained by local regions of monocular dominance or memory of past perceptual history, but rather reflects low-level, spatially localized factors that are stable over periods of weeks. These findings suggest that brief presentation paradigms are inappropriate for their current use in studies of the mechanisms underlying sustained rivalry. However, brief presentations are ideal for investigating early stages of perceptual competition
- …