Biomedical subjects

Frank H Durgin

Publications and source records attributed to Frank H Durgin.

6 recordsLinked to original sources

PubMed2005

Perception of visual speed while moving.

During self-motion, the world normally appears stationary. In part, this may be due to reductions in visual motion signals during self-motion. In 8 experiments, the authors used magnitude estimation to characterize changes in visual speed perception as a result of biomechanical self-motion alone (treadmill walking), physical translation alone (passive transport), and both biomechanical self-motion and physical translation together (walking). Their results show that each factor alone produces subtractive reductions in visual speed but that subtraction is greatest with both factors together, approximating the sum of the 2 separately. The similarity of results for biomechanical and passive self-motion support H. B. Barlow's (1990) inhibition theory of sensory correlation as a mechanism for implementing H. Wallach's (1987) compensation for self-motion.

Biomechanical Phenomena↗

PubMed2005

Self-motion perception during locomotor recalibration: more than meets the eye.

Do locomotor aftereffects depend specifically on visual feedback? In 7 experiments, 116 college students were tested, with closed eyes, at stationary running or at walking to a previewed target after adaptation, with closed eyes, to treadmill locomotion. Subjects showed faster inadvertent drift during stationary running and increased distance (overshoot) when walking to a target. Overshoot seemed to saturate (i.e., reach a ceiling) at 17% after as little as 1 min of adaptation. Sidestepping at test reduced overshoot, suggesting motor specificity. But inadvertent drift effects were decreased if the eyes were open and the treadmill was drawn through the environment during adaptation, indicating that these effects involve self-motion perception. Differences in expression of inadvertent drift and of overshoot after adaptation to treadmill locomotion may have been due to different sets of ancillary cues available for the 2 tasks. Self-motion perception is multimodal.

Adaptation, Psychological↗

PubMed2003

Not letting the left leg know what the right leg is doing: limb-specific locomotor adaptation to sensory-cue conflict.

We investigated the phenomenon of limb-specific locomotor adaptation in order to adjudicate between sensory-cue-conflict theory and motor-adaptation theory. The results were consistent with cue-conflict theory in demonstrating that two different leg-specific hopping aftereffects are modulated by the presence of conflicting estimates of self-motion from visual and nonvisual sources. Experiment 1 shows that leg-specific increases in forward drift during attempts to hop in place on one leg while blindfolded vary according to the relationship between visual information and motor activity during an adaptation to outdoor forward hopping. Experiment 2 shows that leg-specific changes in performance on a blindfolded hopping-to-target task are similarly modulated by the presence of cue conflict during adaptation to hopping on a treadmill. Experiment 3 shows that leg-specific aftereffects from hopping additionally produce inadvertent turning during running in place while blindfolded. The results of these experiments suggest that these leg-specific locomotor aftereffects are produced by sensory-cue conflict rather than simple motor adaptation.

Adaptation, Physiological↗

PubMed2003

Translation and competition among internal representations in a reverse Stroop effect.

In two experiments, the contributions of internal and external competition in a task known to produce a reverse Stroop effect were investigated. In this paradigm, the verbal meaning of an incongruent Stroop stimulus is identified by pointing to a patch of matching color--a task made difficult by the incongruent print color. The experiments showed that there was somewhat more interference when the (irrelevant) color in which the target word was printed was available as an alternate response patch than when it was not. However, significantly more interference was determined by whether the (irrelevant) print color belonged to the set of colors actually used as target words in the course of the experiment. Moreover, the same patterns of interference emerged when the task was altered so that the mere presence of the correct color had to be indicated with a keypress, rather than by pointing to the color's location. Consistent with translation models of Stroop interference, these results demonstrate the theoretical importance of competition among internal representations, rather than among stimuli or responses.

Attention↗

PubMed2002

An ostrich on a rock: commentary on Christie and Barresi (2002).

There are problems with both the theoretical logic and the interpretation of data in Christie and Barresi's (2002) interesting article. The general pattern of results (described as Orwellian) is easily incorporated into an information-processing framework compatible with Dennett's analysis. In particular, different aspects of the illusory motion event are queried at different times and these aspects (line extent and manner of appearance) are not in conflict, so no revision of conscious content is necessary. Second, too much interpretive weight is placed on an anomalous pair of data points (described as Stalinesque) that do not seem fully interpretable within the author's framework and are probably susceptible to one of several alternative interpretations proposed here, though further investigation is necessary.

Consciousness↗

PubMed2002

The time of consciousness and vice versa.

The temporal granularity of consciousness may be far less fine than the real-time information processing mechanisms that underlie our sensitivity to small temporal differences. It is suggested that conscious time perception, like space perception, is subject to errors that belie a unitary underlying representation. E. R. Clay's (The Alternative: A Study in Psychology, 1882) concept of the "specious present," an extended moment represented in consciousness, is suggested as an alternative to the more common notion of instantaneous experience that underlies much reasoning based on the "time of arrival" in consciousness.

Chronobiology Phenomena↗