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Biomedical subjects

R Held

Publications and source records attributed to R Held.

At least 91 records · Page 5Linked to original sources
PubMed1972

Moving visual scenes influence the apparent direction of gravity.

When an observer views a wide-angled display rotating around his line of sight, he both feels his body tilted and sees a vertical straight edge tilted opposite to the moving stimulus. Displacement of the perceived vertical increases with stimulus speed to reach a maximum (averaging 15 degrees) at 30 degrees per second.

Humans↗
PubMed1971

Color- and edge-sensitive channels in the human visual system: tuning for orientation.

After subjects scanned red stripes tilted clockwise off vertical and green stripes tilted equally but counterclockwise, vertical test stripes appeared tilted counterclockwise when red but clockwise when green. As the angle between scanned and test stripes was increased from 0 degrees to 75 degrees , the magnitude of the tilt aftereffect rapidly increased to a peak between 10 degrees and 15 degrees and then dropped close to zero at about 40 degrees , a result consistent with narrowly tuned edge-sensitive channels.

Adaptation, Ocular↗
PubMed1968

Eye tracking of observer-generated target movements.

When an observer moves his arm he shows more precise visual tracking of a target mounted on his fingertip-the eye lags behind the target less and makes fewer corrective saccades-than when he relaxes his arm and the experimenter moves it in a similar manner. Apparently the control system for eye movements can use outflow (efferent) signals in order to anticipate motion of the self-moved target.

Adult↗
PubMed1967

Dissociation of the visual placing response into elicited and guided components.

Kittens reared without sight of their limbs extended their forelimbs when carried down toward the edge of a horizontal surface. However, unlike normally reared kittens, they were not capable of guiding their paws accurately to the solid parts of an interrupted surface. This fractionation of the visually controlled placing response reveals that the guided reach requires an integration of sensorimotor systems not necessary for development of the elicited extension response.

Animals↗
PubMed1967

Visually guided reaching in infant monkeys after restricted rearing.

Infant macaques were reared from birth in an apparatus which pre cluded sight of their body parts. At 35 days postpartum one hand was exposed to view. Visual fixation of this hand was insistent and prolonged; visually guided reaching was poor, but it improved during ten succeeding hours of exposure. Little concomitant improvement occurred in the reaching of the unexposed hand.

Animals↗
PubMedDate not supplied

Binocular function in human infants: correlation of stereoptic and fusion-rivalry discriminations.

Studies of stereopsis in infants have shown that the average age of onset is 3.5 months. This is the same age at which infants first show evidence of another binocular function, namely, preference for binocularly fusible patterns over rivalrous ones. We tracked the development, using two-alternative forced-choice preferential looking, of the two forms of binocular function in 17 infants, 11 male and six female. They were tested at regular intervals until they showed preferences for 1) a fusible pattern (vertical stripes presented to each eye) over a rivalrous one (vertical stripes presented to one eye, horizontal stripes to the other), and 2) a line stereogram of 32 min crossed disparity over a comparable stereogram with zero disparity. The correlation between the age of onset of the fusion preference (mean 12.4 weeks) and the age of onset of stereopsis (mean 11.0 weeks) was r = 0.79. Female infants showed a preference for the fusible stimulus at a mean age of 9.9 weeks, significantly earlier than the males at a mean age of 13.8 weeks. Similarly, females also showed evidence of stereopsis at an earlier age (9.1 weeks compared with 12.1 weeks for males).

Age Factors↗