caused by either a translational displacement of the simulated eye position in the horizontal direction, or by an angular rotation of the simulated eye direction along the yaw axis. The former made the visual stimulus obtain motion parallax, which could be a cue for depth perception, but the latter did
Sanders M. C.
Chang N. N.
Hiss M. M.
Uchanski R. M.
Hullar T. E.
( 2011 ).
Temporal binding of auditory and rotational stimuli ,
Experimental Brain Research
Giordano P. R.
Beykirch K. A.
Information about a sound source’s location in the front/back dimension is present in the relation between head rotation and the resulting changes in interaural time- or level-difference cues. The use of such dynamic cues for localization requires the auditory system to have access to an accurate representation of the orientation and motion of the head in space. We measured, in active and passive rotation conditions, and as a function of head-rotation angle and velocity, normally hearing human listeners’ ability to localize front and rear sources of a low-frequency (0.5–1 kHz) noise band that was not accurately localizable in the absence of head motion. Targets were presented while the head was in motion at velocities of 50–400°/s (active neck rotation) or 25–100°/s (whole-body passive rotation), and were gated on and off as the head passed through a variable-width spatial window. Accuracy increased as window width was increased, which provided access to larger interaural cue changes, but decreased as head-turn velocity increased, which reduced the duration of the stimuli. For both active and passive rotation, these effects were almost exactly reciprocal, such that performance was related primarily to the duration of the stimulus, with ∼100 ms duration required for 75% correct front/back discrimination regardless of the cue-change magnitude or mode of rotation. The efficacy of the dynamic auditory cues in the passive rotation condition suggests that vestibular input is sufficient to inform the auditory system about head motion.
Soybean ( Glycine max (L.) Merr.) is an important multi-purpose crop worldwide. In the USA, it is produced mostly in rotation with maize ( Zea mays L.), and the soybean cyst nematode (SCN; Heterodera glycines Ichinohe) is its most persistent pest (Donald et al. , 2006 ). Ever since its
Seeing and Perceiving 23 (2010) 241–261 brill.nl/sp Detecting Sudden Changes in Dynamic Rotation Displays J. Timothy Petersik ∗ and Rachael L. Thiel Ripon College, Department of Psychology, Ripon College, P.O. Box 248, Ripon, WI 54971, USA Received 17 September 2009; accepted 30 April 2010
Seeing and Perceiving 23 (2010) 373–383 brill.nl/sp Testing the Egocentric Mirror-Rotation Hypothesis Cornelius Muelenz ∗ , Heiko Hecht and Matthias Gamer Institute of Psychology, Johannes-Gutenberg-Universität Mainz, Wallstrasse 3, 55099 Mainz, Germany Received 9 November 2009; accepted 18
Seeing and Perceiving 24 (2011) 315–350 brill.nl/sp Partitioning Contrast or Luminance Disparity into Perceived Intensity and Rotation Richard S. Hetley 1 , ∗ and Wm Wren Stine 2 , ∗ 1 University of California, 3151 Social Science Plaza A, Irvine, CA 92697-5100, USA 2 Department of Psychology
Crop rotation, i.e. the rotation of various crops and the observation of fallow years as part of the cultivation process, was employed in the modern era to avoid stressing the soil through monoculture and to prevent plant diseases. Already in the Early Middle Ages, various systems had been
Imbalance among patients with vestibular hypofunction has been related to inadequate compensatory eye movements in response to head movements. However, symptoms of imbalance might also occur due a temporal mismatch between vestibular and other balance-related sensory cues. This temporal mismatch could be reflected in a widened temporal binding window (TBW), or the length of time over which simultaneous sensory stimuli may be offset and still perceived as simultaneous. We hypothesized that decreased vestibular input would lead to a widening of the temporal binding window. We performed whole-body rotations about the earth-vertical axis following a sinusoidal trajectory at 0.5 Hz with a peak velocity of 60°/s in four normal subjects. Dichotic auditory clicks were presented through headphones at various phases relative to the rotations. Subjects were asked to indicate whether the cues were synchronous or asynchronous and the TBW was calculated. We then simulated decreased vestibular input by rotating at diminished peak velocities of 48, 24 and 12°/s in four normal subjects. TBW was calculated between ±1 SD away from the mean on the psychometric curve. We found that the TBW increases as amplitude of rotation decreases. Average TBW of 251 ms at 60°/s increased to 309 ms at 12°/s. This result leads to the novel conclusion that changes in temporal processing may be a mechanism for imbalance in patients with vestibular hypofunction.
Falls are one of the leading causes of disability in the elderly. Previous research has shown that falls may be related to changes in the temporal integration of multisensory stimuli. This study compared the temporal integration and processing of a vestibular and auditory stimulus in younger and older subjects. The vestibular stimulus consisted of a continuous sinusoidal rotational velocity delivered using a rotational chair and the auditory stimulus consisted of 5 ms of white noise presented dichotically through headphones (both at 0.5 Hz). Simultaneity was defined as perceiving the chair being at its furthest rightward or leftward trajectory at the same moment as the auditory stimulus was perceived in the contralateral ear. The temporal offset of the auditory stimulus was adjusted using a method of constant stimuli so that the auditory stimulus either led or lagged true simultaneity. 15 younger (ages 21–27) and 12 older (ages 63–89) healthy subjects were tested using a two alternative forced choice task to determine at what times they perceived the two stimuli as simultaneous. Younger subjects had a mean temporal binding window of 334 ± 37 ms (mean ± SEM) and a mean point of subjective simultaneity of 83 ± 15 ms. Older subjects had a mean TBW of 556 ± 36 ms and a mean point of subjective simultaneity of 158 ± 27. Both differences were significant indicating that older subjects have a wider temporal range over which they integrate vestibular and auditory stimuli than younger subjects. These findings were consistent upon retesting and were not due to differences in vestibular perception thresholds.