Primacy and frequency effects in absolute judgments of visual velocity

In absolute judgment tasks, identical stimuli are rated higher (or lower) when presented in a series of more frequent small (or large) stimuli. Using visual stimuli differing in velocity, we show that this conventional frequency effect is largely modulated by the primacy effect--that is, by the stimuli occurring on the early trials of a run. In Experiment 1, a frequency-like primacy effect was obtained with equal-frequent velocities. Identical velocities were rated faster when mainly slow rather than fast ones occurred on initial trials. In Experiment 2, we contrasted the frequency effect and the primacy effect: In runs with frequent slow velocities, mainly fast ones occurred earlier, whereas in runs with infrequent slow velocities, mainly slow ones did so. Lack of differences of ratings in the two conditions suggests that the two effects canceled each other. In Experiment 3, when mainly frequent velocities occurred earlier, the conventional frequency effect was obtained. We conclude that the conventional frequency effect represents a combination of the primacy effect and the pure frequency effect.     

Speed perception is affected by the Ebbinghaus-Titchener illusion

We examined whether the apparent extent of motion affects speed perception. On the first presentation of each trial, a light dot travelled horizontally across a central circle of one of the Ebbinghaus configurations (with either small or large inducing elements). On the second presentation, observers adjusted the speed of a dot moving within the central circle alone so as to match the speed perceived in the first presentation. For all stimulus speeds (1.3, 2.1, and 5.5 deg s-1), the matched speed with small inducing circles was systematically less than that with large inducing circles. The findings indicate that the perceived speed depends on the apparent extent of motion: the larger the apparent size of a frame, the slower the apparent speed. These results are consistent with the predictions of transposition effects in visual motion.     

Timing accuracy in motion extrapolation: reverse effects of target size and visible extent of motion at low and high speeds

By varying target size, speed, and extent of visible motion we examined the timing accuracy in motion extrapolation. Small or large targets (0.2 or 0.8 deg) moved at either 2.5, 5, or 10 deg s(-1) across a horizontal path (2.5 or 10 deg) and then vanished behind an occluder. Observers responded when they judged that the target had reached a randomly specified position between 0 and 12 deg. With higher speeds, the timing accuracy (the reverse of absolute error) was better for small than for large targets, and for long than for short visible extents. With low speed, these effects were reversed. In addition, while long visible extents yielded a greater accuracy at high than at low speeds, for short extents the accuracy was much better with the low speed. The findings suggest that, when extrapolating motion with targets and visible extents of different sizes, the visual system implements different scaling algorithms depending on target speed. At higher speeds, processing of visible and occluded motion is likely to share a common scaling mechanism based on velocity transposition. Reverse effects for target size and extent of visible motion at low and high speeds converge with the assumption of two distinct speed-tuned motion-processing mechanisms in human vision.     

A psychophysiological model of emotion space.

Despite a wide variety of emotions that can be subjectively experienced, the emotion space has consistently revealed a low dimensionality. The search for corresponding somato-visceral response patterns has been only moderately successful. The authors suggest a solution based on an assumed parallelism between emotion coding and color coding. According to the color detection model proposed by Sokolov and co-workers, neurons responsible for color detection are triggered by a combination of excitations in a limited number of input cells. Similarly, a limited number of input channels may feed complex emotion detectors being located on a hypersphere in a four-dimensional emotion space, the three angles of which correspond to emotional tone, intensity, and saturation, in parallel to hue, lightness, and saturation in color perception. The existence of such a four-dimensional emotion space in the subjective domain is shown by using schematic facial expressions as stimuli. A neurophysiological model is provided in which reticular, hypothalamic, and limbic structures constitute input channels of an emotion detecting system, thus acting as the first layer of emotion predetectors. Hypothalamic neurons with differential sensitivity for various transmitters may elicit a subsequent selective activation in a second layer of predetectors at the thalamic level. The latter are suggested to trigger emotion detectors located in cortical areas, the action of which should be revealed by measures of central nervous system activity. Preliminary results from evoked potential studies show that switching between schematic faces that express different emotions may be used as an objective measure for establishing a psychophysiological emotion space.     

Response scale transfer for visual speed

By reversing the presentation order and frequency of stimuli between two series of trials, we studied how the category scale for visual speed is transferred across stimulus contexts. Participants judged five stimulus speeds, using three categories (slow, moderate, and fast). In Experiment 1, mainly frequent speeds (either low or high) occurred on the initial trials. This manipulation produced divergent preshift ratings for identical stimuli. Although subsequent reversal of stimulus context resulted in a reversal of scales, the adjustment was incomplete: The postshift ratings did not match the comparable preshift ones. In Experiment 2, mainly infrequent speeds were presented initially. Now the preshift ratings coincided, but higher postshift ratings occurred with the frequent high-speed rather than with the frequent low-speed stimuli. We conclude that with transfer into a new context, the spontaneous adjustment of response scale is determined (1) by the preshift primacy and the postshift frequency effects and (2) by the preshift frequency effect extended to the postshift trials.     

Sex as an obligation and interpersonal communication among Norwegian heterosexual couples

This study examines the prevalence of having sex as a means of satisfying one's partner among a random sample of 398 heterosexual couples with non-problematic, mild or manifest reduced sexual desire. Data collection was carried out by questionnaires. Two of three women and one of five men with manifest distressing reduced sexual desire had had obligatory sex. Among women with symptoms of mild reduced sexual desire, there was an association between obligatory sex and lack of acknowledgement of one's sexual needs, as well as a lack of communication with one's partner regarding how to be sexually pleased. In men with manifest reduced sexual desire there was an association between obligatory sex and discussion of one's sexual needs, and sexual fantasies with the partner. Thus, men with desire problems seem to communicate with their partner about their sexuality, whereas women seem not to talk with their partner about their sexual needs.