Displacement of location in illusory line motion.

Six experiments examined displacement in memory for the location of the line in illusory line motion (ILM; appearance or disappearance of a stationary cue is followed by appearance of a stationary line that is presented all at once, but the stationary line is perceived to "unfold" or "be drawn" from the end closest to the cue to the end most distant from the cue). If ILM was induced by having a single cue appear, then memory for the location of the line was displaced toward the cue, and displacement was larger if the line was closer to the cue. If ILM was induced by having one of two previously visible cues vanish, then memory for the location of the line was displaced away from the cue that vanished. In general, the magnitude of displacement increased and then decreased as retention interval increased from 50 to 250 ms and from 250 to 450 ms, respectively. Displacement of the line (a) is consistent with a combination of a spatial averaging of the locations of the cue and the line with a relatively weaker dynamic in the direction of illusory motion, (b) might be implemented in a spreading activation network similar to networks previously suggested to implement displacement resulting from implied or apparent motion, and (c) provides constraints and challenges for theories of ILM.

Representational momentum is not (totally) impervious to error feedback.

The influence of feedback on representational momentum for the final location of a moving target was examined in 3 experiments. The presence of binary feedback (correct, error) during practise trials or during larger blocks of experimental trials did not reduce representational momentum, nor did the presence of more informative feedback specifying the direction of error (error-in front of, error-behind) during larger blocks of experimental trials reduce representational momentum. Effects on representational momentum of whether feedback was consistently provided were inconsistent. Even though feedback did not reduce representational momentum per se, feedback did influence the probability of a same response for different probe positions. Implications of the data for R. A. Finke and J. J. Freyd's (1985; J. J. Freyd, 1987) claim that representational momentum is impervious to error feedback, and possible roles of perceptual learning in representational momentum, are discussed.

Representational momentum and anisotropies in nearby visual space.

The possibility of anisotropies in visual space in and near the final location of a moving target was examined. Experiments 1 and 2 presented a moving target, and after the target vanished, participants indicated the final location of the leading or trailing edge of the target. Memory for both edges was displaced forward from the actual final locations, and the magnitude of displacement was smaller for the leading edge. Experiments 3 and 4 also presented stationary objects in front of and behind the final location of the target, and participants indicated the location of the nearest or farthest edge of one of the stationary objects. Memory for the near or far edge of an object in front of the target was displaced backward, and memory for the near or far edge of an object behind the target was displaced forward; the magnitude of displacement was larger for objects in front of the target and when the edge was farther away. The findings (a) suggest representational momentum is associated with an anisotropy of visual space that extends across and outward from the moving target and (b) are consistent with previous findings regarding estimation of time-to-contact, anorthoscopic perception, and memory psychophysics.

Does Allocation of Attention Influence Relative Velocity and Strength of Illusory Line Motion?

In illusory line motion, presentation of a cue is followed by presentation of a nearby stationary line, and the line is perceived to "unfold," "expand," or "extend" away from the cue. Effects of the allocation of attention regarding where the cue or the line would be presented were measured in three experiments, and ratings of relative velocity and relative strength of illusory motion were collected. Findings included (a) relative velocity and relative strength decreased with increases in SOA from 50 to 450 ms, (b) relative velocity and relative strength were not influenced by whether illusory motion moved from one end of the line to the other or from both ends toward the middle of the line, (c) increased uncertainty regarding where the line would appear did not influence relative velocity or relative strength, and (d) valid pre-cues regarding the location of a cue resulted in faster relative velocity than did invalid pre-cues, but pre-cue validity did not influence relative strength. Implications of these findings for the relationship of such illusory motion and attention (e.g., divided attention, shifts in attended location) are considered.

Perceived causality, force, and resistance in the absence of launching.

In the launching effect, a moving object (the launcher) contacts a stationary object (the target), and upon contact, the launcher stops and the target begins moving in the same direction and at the same or slower velocity as previous launcher motion (Michotte, 1946/1963). In the study reported here, participants viewed a modified launching effect display in which the launcher stopped before or at the moment of contact and the target remained stationary. Participants rated perceived causality, perceived force, and perceived resistance of the launcher on the target or the target on the launcher. For launchers and for targets, increases in the size of the spatial gap between the final location of the launcher and the location of the target decreased ratings of perceived causality and ratings of perceived force and increased ratings of perceived resistance. Perceived causality, perceived force, and perceived resistance exhibited gradients or fields extending from the launcher and from the target and were not dependent upon contact of the launcher and target. Causal asymmetries and force asymmetries reported in previous studies did not occur, and this suggests that such asymmetries might be limited to typical launching effect stimuli. Deviations from Newton's laws of motion are noted, and the existence of separate radii of action extending from the launcher and from the target is suggested.

An effect of contrast and luminance on visual representational momentum for location.

Effects of the contrast of target luminance and background luminance, and of the absolute level of target luminance, on representational momentum for the remembered final location of a previously viewed moving target were examined. Targets were high in contrast or luminance, decreasing in contrast or luminance, increasing in contrast or luminance, or low in contrast or luminance; the background was black or white. Representational momentum for target location was larger if targets were high or increasing in contrast or luminance and smaller if targets were low or decreasing in contrast or luminance. Representational momentum for target location was larger if targets were presented on a white background than on a black background. Implications for theories of localization and for theories of representational momentum are discussed.

A Fröhlich effect and representational gravity in memory for auditory pitch.

Memory for the initial pitch of an auditory target that increased or decreased in auditory frequency was examined. Memory was displaced forward in the direction of pitch motion, and this is consistent with the Fröhlich effect previously observed for visual targets moving in visual physical space. The Fröhlich effect for pitch increased with faster target velocity and decreased if an auditory cue with the same pitch as the initial pitch of the target was presented before the target was presented. The Fröhlich effect was larger for descending pitch motion than for ascending pitch motion, and this is consistent with an influence of representational gravity. The data suggest that representation of auditory frequency space exhibits some of the same biases as representation of visual physical space, and implications for theories of attention in displacement and for crossmodal and multisensory representation of space are discussed.

Effects of temporal and spatial separation on velocity and strength of illusory line motion.

The effects of line length and of spatial or temporal distance on illusory line motion (i.e., on the perception that a stationary line unfolds or expands away from a previously presented stationary cue) were examined in five experiments. Ratings of relative velocity decreased with increases in stimulus onset asynchrony between appearance of the cue and appearance of the line (from 50 to 450 ms), whereas the extremity of ratings of direction (i.e., strength of the ratings of illusory line motion) increased with increases in stimulus onset asynchrony (from 50 to either 250 or 450 ms). Ratings of relative velocity increased with increases in line length, whereas ratings of direction were not influenced by increases in line length. Ratings of relative velocity and direction were not influenced by increases in the distance of the near or the far end of the line from the cue. Implications of these data for attentional theories and apparent-motion theories of illusory line motion are discussed.

Effects of spatial cuing on the onset repulsion effect.

Effects of cuing the onset (initial) location of a moving target on memory for the onset location of that target were examined. If a cue presented prior to target onset indicated the location where that target would appear, the onset repulsion effect (in which the judged initial location of the target was displaced in the direction opposite to target motion) was decreased, and the onset repulsion effect was smaller if the cue was valid than if the cue was invalid. If a cue presented during target motion or after the target vanished indicated the location where that target had appeared, the onset repulsion effect was eliminated. The data (1) suggest that positional uncertainty might contribute to the onset repulsion effect, (2) provide the first evidence of an effect of expectancy regarding target trajectory on the onset repulsion effect, and (3) are partially consistent with previous data involving effects of attention and spatial cuing on the Fröhlich effect and on representational momentum.