Marie Luise Mittelstaedt

Homing by path integration

The paper presents experimental evidence for homing by path integration in a bird. Using a mammalian model case, the essentials of a cybernetical theory of this type of navigation are developed. As a consequence of its application to the extant data on geese, the necessary information about the translatory component of the animal’s movement along its path appears to be provided by the visual system, viz. the translatory component of the visual flow, whereas the rotatory information must (also) have non-visual sources, e.g. the semicircular canals or the magnetic field.

How to explain a constant subjective vertical at constant high speed rotation about an earth-horizontal axis

When rotated in darkness about an earth-horizontal axis at speeds above 0.2-0.5 Hz, subjects, instead of feeling rotated, experience a constant (though extrapersonally diverse) position in space and a constant visual vertical (SV). Computer simulation shows that this phenomenon cannot be explained by the extant models of Mayne (1) and Ormsby (2) about the interaction of otoliths and semicircular canals. It follows, however, from a static theory of the SV (3) if, as in the presently proposed dynamic model, the otolith afference is processed by a low-pass filter. At high speed rotation this filter can only be passed by the force-independent, temporally invariant components of the otolith information. Such force-independent components are bound to result from biassed resting discharges, and have previously been shown to affect the SV and the self-adopted horizontal position. The interaction of otoliths and canals proposed by the model does provide a veridical vertical in a working range of angular frequencies and hence a basis for inertial navigation.

Idiothetic course control and visual orientation

The animals used in these experiments are able to maintain course by information about a relation between parts or states of their own body which is correlated to turns (“idiothetic” course control). If one makes the animal deviate from such an idiothetic course by exposing it to a suitably arranged visual stimulus, it shows a compensatory turn when the original situation is reestablished. It is shown that the idiothetic course control operates also in the presence of external orienting cues. Consequences for the interpretation of relevant data are discussed and a new hypothesis about the origin of menotactic light courses is suggested.

Influence of Centrifugal Force on Angular Velocity Estimation

In darkness, subjects were positioned face forward (or backward, resp.) on a rotating disk at a radial distance r of 0-1.6 m. They were then accelerated within 0.8 s to a constant rotation (omega = 0.35-0.87 rad/s), and successively indicated whenever they felt turned through 180 degrees. Fairly veridical at first, these indications lagged progressively as though subjective velocity declined exponentially to zero. Plots of ordinal number of indications over time of indication revealed idiosyncratic time constants (20-90 s) that were independent of disk velocity at r = 0, but increased with radial distance, namely, with r omega 2, hence depended on centrifugal force. When, after constant rotation of at least 2 min the subjects were stopped (within 1.2 s), and asked to indicate 180 degrees turns as above, the time constants of all subjects were independent of radius and disk velocity, as expected, if the added orthogonal force caused the prolonged time constants in the former paradigm.

Angular Velocity Estimation under Varying Linear Acceleration

This study investigates the effect of angular and translatory acceleration on the estimation of angular displacement during and after constant passive rotation. Subjects were tested in standing or lying attitude. Because these experiments were part of a study on human navigation (Mittelstaedt and Glasauer, 1991) experimental conditions remained largely within the range of everyday movements.