Psychological Research

doi: 10.1007/BF00309075pmid: N/A

Runeson, Sverker

doi: 10.1007/BF00309076pmid: 4449922

Most students of visual velocity perception implicitly assume that constant velocity is seen as such. This notion was challenged and shown to be inadequate in four experiments. A CRT-generated bright spot moved in a linear path according to different velocity time functions. Observers compared these movements pairwise as to their perceived constancy of velocity, or drew graphs describing perceived velocity along the track. Objects moving with constant velocity appear to move fast in the beginning and suddenly slow down to a much lower velocity. There is also a qualitative difference between the start phase and the rest. To be seen as constant, a movement must start smoothly with a certain acceleration and later level off to a constant velocity (natural motion). Such movements also look slower than others with the same average velocity. The results are taken to imply the existence of a perceptual concept of velocity which includes or presupposes a natural start. Consequences for velocity scaling, acceleration thresholds, and other motion perception studies, as well as relations to eye movements and conceptual problems, are discussed.

Prinz, Wolfgang; Scheerer-Neumann, Gerheid

doi: 10.1007/BF00309077pmid: 4449921

In an attempt to analyze some aspects of the task requirements in multiattribute stimulus classification (MASC), “actual” task demands are contrasted with “nominal” (i.e. theoretically assumed) task demands. On the basis of theoretical considerations and some experimental data corrections of the usually adopted picture of the task are suggested in three respects: 1. For many MASC tasks the component processes involved can better be conceived to be feature detection operations than dimensional discrimination processes. 2. When few dimensions are relevant, irrelevant interrogation may interfere with relevant processing. 3. When many dimensions are relevant, attribute chunking may occur, i.e. there may actually be fewer component processes than is theoretically assumed. — It is concluded that using multiattribute stimulus sets does not help to solve the problem of controlling or identifying functional units of information processing.

Povel, Dirk-Jan

doi: 10.1007/BF00309078pmid: 4449923

The development of a visual speech apparatus that gives information about the identity of vowels spoken in a CVC context is described. The principle of the apparatus is based on a dimensional analysis of the vowel spectra. In developing the device, the demands of the specific speech correction setting of the deaf were taken into account as much as possible. From a number of physical and statistical analyses of vowels in different consonantal surroundings, it appeared possible to separate two vowels quite satisfactorily. In describing the apparatus, special attention is given to some technical features that were added to satisfy the requirements of speech correction. Finally, the operation of the device is tested with a large number of monosyllables pronounced by 20 speakers. The results indicate that the apparatus satisfies the conditions stated for practical use.

Povel, Dirk-Jan

doi: 10.1007/BF00309079pmid: 4449924

The Vowel Corrector, a device giving visual information about the identity of vowels spoken in monosyllabic words, was tested on a group of deaf boys. The description of the actual experiment is preceded by a number of considerations relating to the application of an articulation corrector in a speech therapy program for the deaf.

Scheerer-Neumann, Gerheid

doi: 10.1007/BF00309080pmid: 4449925

Paivio's dual coding hypothesis proposes that the retention of pictures and concrete words can be mediated by both visual and verbal codes. The present study investigates the time course of the formation and utilization of the visual and verbal codes of pictures and words in a “same”-“different” RT-task involving physical (Picture-Picture; Word-Word) and semantic (Word-Picture; Picture-Word) matches. The ISI was varied between 50 and 2000 msec. The four matching conditions were either constant within a block of trials (Exp. I) or partially mixed (Exp. II). Exp. I showed that at long ISIs (>500 msec.) the comparisons in all matching conditions were based on visual codes; Ss either retained the visual code of the first stimulus (physical matches) or generated the visual code of the expected second stimulus (semantic matches). Under the conditions of Exp. II the visual code of the first stimulus was not actively retained. Except for very short ISIs (≤250 msec.) only a single code, the verbal code was used for comparisons of all stimulus combinations. Paivio's dual code hypothesis thus must be modified to account for code utilization in a matching task. The comparison between “same” RTs of the physical match conditions from both experiments suggests that two stages of visual storage were involved in the task, viz. the visual sensory store for ISIs ≤250 msec. and the visual short-term store for ISIs ≥ 500 msec.