Flash-induced forward and reverse illusory line motion in offset bars

Illusory line motion (ILM) refers to perception of motion in a bar that onsets or offsets all at once. When the bar onsets or offsets between two boxes after one of the boxes flashes, the bar appears to shoot out of the flashed box (_flashILM). If the bar offsets during the flash, it appears to contract into the flashed box (reverse ILM; rILM). Onset bars do not show rILM. Moreover, rILM and _flashILM are not correlated, indicating they are two different illusions. To date, rILM has only been studied using a 50-ms flash where the bar offsets 16.7 ms after flash onset. It is not clear if rILM is due to the 16.7-ms flash-bar-removal stimulus onset asynchrony (SOA) or due to the flash offsetting after the bar. The current studies explore these parameters to better understand the conditions that lead to rILM. The results suggest that _flashILM is sensitive to the temporal interval between flash onset and bar offset, while rILM appears to arise when the flash offsets after the bar has been removed regardless of the temporal interval between flash onset and bar removal. These results are consistent with _flashILM reflecting visual exogenous attention while rILM may reflect the low-level spreading of subthreshold activation radiating from the flashed box. The findings are incorporated into the recent work that suggests that the literature concerning ILM is possibly conflating a number of different illusions of line motion, including polarized gamma motion (PGM), transformational apparent motion (TAM), and exogenous attention induced motion (_flashILM).     

Preattentive Perception of Multiple Illusory Line-Motion: A Formal Model of Parallel Independent-Detection in Visual Search

The phenomenon referred to as illusory line-motion (ILM; O. Hikosaka, S. Miyauchi, & S. Shimojo, 1993a) has been described as a measure of the local facilitation of attention gradient. However, J. Kawahara, K. Yokosawa, S. Nishida, and T. Sato (1996) have demonstrated a spatially parallel search for an “odd man out” in the ILM direction. Apart from showing preattentive ILM perception in terms of an analogy between line-motion and apparent motion, the authors examined whether ILM perception is possible without attention from another point of view. Four experiments revealed that the ILM target can be detected in parallel without invoking attentional facilitation and invalidated the possible contribution of attentional set in parallel ILM search. Participants were able to correctly detect the ILM target among multiple nontargets, even when the line orientation was changed from trial to trial. The authors' independent-detection model predicted ILM search performance well on several occasions. These findings strongly support a preattentive and stimulus-driven explanation of ILM perception.     

Preattentive perception of multiple illusory line-motion: a formal model of parallel independent-detection in visual search

The phenomenon referred to as illusory line-motion (ILM; O. Hikosaka, S. Miyauchi, & S. Shimojo, 1993a) has been described as a measure of the local facilitation of attention gradient. However, J. Kawahara, K. Yokosawa, S. Nishida, and T. Sato (1996) have demonstrated a spatially parallel search for an "odd man out" in the ILM direction. Apart from showing preattentive ILM perception in terms of an analogy between line-motion and apparent motion, the authors examined whether ILM perception is possible without attention from another point of view. Four experiments revealed that the ILM target can be detected in parallel without invoking attentional facilitation and invalidated the possible contribution of attentional set in parallel ILM search. Participants were able to correctly detect the ILM target among multiple nontargets, even when the line orientation was changed from trial to trial. The authors' independent-detection model predicted ILM search performance well on several occasions. These findings strongly support a preattentive and stimulus-driven explanation of ILM perception.     

Illusory line motion and transformational apparent motion during continuous flash suppression1

A static bar is perceived to dynamically extend from a peripheral cue (illusory line motion (ILM)) or from a part of another figure presented in the previous frame (transformational apparent motion (TAM)). We examined whether visibility for the cue stimuli affected these transformational motions. Continuous flash suppression, one kind of dynamic interocular masking, was used to reduce the visibility for the cue stimuli. Both ILM and TAM significantly occurred when the d' for cue stimuli was zero (Experiment 1) and when the cue stimuli were presented at subthreshold levels (Experiment 2). We discuss that higher‐order motion processing underlying TAM and ILM can be weakly but significantly activated by invisible visual information.     

Endogenous attention and illusory line motion reexamined

P. Downing and A. Treisman's (1997) failure to replicate an effect of endogenous attention on the direction of illusory line motion (ILM) was reexamined. Four experiments with slightly modified stimulus presentation methods based on gradient theories of ILM found that endogenous attention directed to 1 of 2 similar priming objects is capable of influencing experienced motion direction within a subsequently presented line. The endogenous effect on ILM was consistent with a concomitant response-time discrimination task, was robust across naive and informed participants, occurred whether eye fixation was monitored or not, and occurred under conditions where multiple motion response categories were available to participants. The endogenous effect disappeared when participants moved their eyes to the attended item, when there was no motivation to endogenously attend, and when the presentation methods of P. Downing and A. Treisman (1997) were used.     

Structure-from-motion: dissociating perception, neural persistence, and sensory memory of illusory depth and illusory rotation

In the structure-from-motion paradigm, physical motion on a screen produces the vivid illusion of an object rotating in depth. Here, we show how to dissociate illusory depth and illusory rotation in a structure-from-motion stimulus using a rotationally asymmetric shape and reversals of physical motion. Reversals of physical motion create a conflict between the original illusory states and the new physical motion: Either illusory depth remains constant and illusory rotation reverses, or illusory rotation stays the same and illusory depth reverses. When physical motion reverses after the interruption in presentation, we find that illusory rotation tends to remain constant for long blank durations (T _blank ≥ 0.5 s), but illusory depth is stabilized if interruptions are short (T _blank ≤ 0.1 s). The stability of illusory depth over brief interruptions is consistent with the effect of neural persistence. When this is curtailed using a mask, stability of ambiguous vision (for either illusory depth or illusory rotation) is disrupted. We also examined the selectivity of the neural persistence of illusory depth. We found that it relies on a static representation of an interpolated illusory object, since changes to low-level display properties had little detrimental effect. We discuss our findings with respect to other types of history dependence in multistable displays (sensory stabilization memory, neural fatigue, etc.). Our results suggest that when brief interruptions are used during the presentation of multistable displays, switches in perception are likely to rely on the same neural mechanisms as spontaneous switches, rather than switches due to the initial percept choice at the stimulus onset.     

Illusory line motion is not caused by object-differentiating mechanisms or endogenous attention

Christie and Klein [2005. Does attention cause illusory line motion? Perception & Psychophysics, 67(6), 1032–1043] published line motion ratings consistent with illusory line motion (ILM) after peripheral endogenous cues but not central arrow cues. When attention was directed endogenously on the basis of the shape of one of two peripherally presented objects, participants reported small, but significant motion away from the attended object, and this was attributed to participant bias, or to a peripherally directed object-based attention system endogenously recruited to differentiate the peripheral shapes. By using a unique cueing method with identical peripheral markers, but still allowing them to act as cues, the findings of Christie and Klein Experiment 4 were replicated. This reduces the likelihood that object discrimination or object attention mechanisms are responsible for the reported ILM-like effects.     

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.     

Does attention cause illusory line motion?

Illusory line motion (ILM) has been shown to occur when a line is presented with one end next to a previously stimulated location. The line appears to be drawn away from the site of stimulation. It has been suggested that this is because of the allocation of attention to the stimulated site. Using an endogenous attentional manipulation (a central arrow cue) with no differences in the display between the two ends of the line at the time of line presentation or immediately prior, no ILM was detected, though there was a small effect in the opposite direction. Those who have found endogenously induced ILM have used an endogenous cue based on a property of a location marker that indicated the cued location. Changing the method of cuing to one based on a property of a peripheral marker instead of a central arrow produced a small but significant report of ILM. The small magnitude of the effect, participant self-reports, and the absence of the effect in the purely endogenous condition, suggest that this was merely a bias. ILM is not generated by endogenous attention shifts.     

Retinal,attentional, and causal aspects of illusory-motion directionality

Extended objects presented instantaneously appeared to propagate or grow into their final shape. A strong bias was found toward perceiving straight lines to grow away from the observer's point of fixation. If attention and fixation were not directed to the same point of the visual field, both influenced illusory motion directionality, and if another small object was present on the screen at a location that was neither fixated nor attended to, the object that was instantaneously presented seemed to grow away from this point. Thus, three factors are involved in illusory-motion directionality: biases toward perceiving objects spreading away from the fixation point, away from an attended area, and away from preexisting objects. The experiments indicate that a satisfactory explanation of the illusion has to include bottom-up and top-down processes. They also challenge existing theories of motion detection.     

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.     

Aging and involuntary attention capture: electrophysiological evidence for preserved attentional control with advanced age

The present study examined whether people become more susceptible to capture by salient objects as they age. Participants searched a target display for a letter in a specific color and indicated its identity. In Experiment 1, this target display was preceded by a non-informative cue display containing one target-color box, one ignored-color box, and two white boxes. On half of the trials, this cue display also contained a salient-but-irrelevant abrupt onset. To assess capture by the target-color cue, we used the N2pc component of the event-related potential, thought to reflect attentional allocation to the left or right visual field. The target-color box in the cue display produced a substantial N2pc effect for younger adults and, most importantly, this effect was not diminished by the presence of an abrupt onset. Therefore, the abrupt onset was unable to capture attention away from the target-color cue. Critically, older adults demonstrated the same resistance to capture by the abrupt onset. Experiment 2 extended these findings to irrelevant color singleton cues. Thus, we argue that the ability to attend to relevant stimuli and resist capture by salient-but-irrelevant stimuli is preserved with advancing age.     

Transient attention degrades perceived apparent motion

Transient spatial attention refers to the automatic selection of a location that is driven by the stimulus rather than a voluntary decision. Apparent motion is an illusory motion created by stationary stimuli that are presented successively at different locations. In this study we explored the effects of transient attention on apparent motion. The motion target presentation was preceded by either valid attentional cues that attract attention to the target location in advance (experiments 1-4), neutral cues that do not indicate a location (experiments 1, 3, and 4), or invalid cues that direct attention to a non-target location (experiment 2). Valid attentional cues usually improve performance in various tasks. Here, however, an attentional impairment was found. Observers' ability to discriminate the direction of motion diminished at the cued location. Analogous results were obtained regardless of cue type: singleton cue (experiment 1), central non-informative cue (experiment 2), or abrupt onset cue (experiment 3). Experiment 4 further demonstrated that reversed apparent motion is less likely with attention. This seemingly counterintuitive attentional degradation of perceived apparent motion is consistent with several recent findings, and together they suggest that transient attention facilitates spatial segregation and temporal integration but impairs spatial integration and temporal segregation.     

Forms of momentum across space: Representational,operational, and attentional

Cognition can exhibit biases consistent with future expectations, and some of these biases result in momentum-like effects and have been linked with the idea of an internalization of the effects of momentum. These momentum-like effects include representational momentum, operational momentum, and attentional momentum. Similarities and differences between these different momentum-like effects are considered. Hubbard’s (2005) review of representational momentum is updated to include studies published since that review appeared, and the first full reviews of operational momentum and attentional momentum are provided. It is suggested that (1) many variables that influence one of these momentum-like effects have a similar influence on another momentum-like effect, (2) representational momentum, operational momentum, and attentional momentum reflect similar or overlapping mechanisms, and operational momentum and attentional momentum are special cases of representational momentum, and (3) representational momentum, operational momentum, and attentional momentum reflect properties of a more general spatial representation in which change or transformation of a stimulus is mapped onto motion in a spatial coordinate system.     

Attentional sampling of multiple wagon wheels

Attending to a periodic motion stimulus can induce illusory reversals of the direction of motion. This continuous wagon wheel illusion (c-WWI) has been taken to reflect discrete sampling of motion information by visual attention. An alternative view is that it is caused by adaptation. Here, we attempt to discriminate between these two interpretations by asking participants to attend to multiple periodic motion stimuli: The discrete attentional sampling account, but not the adaptation account, predicts a decrease of c-WWI temporal-frequency tuning with set size (with a single periodic motion stimulus the c-WWI is tuned to a temporal frequency of 10 Hz). We presented one to four rotating gratings that occasionally reversed direction while participants counted reversals. We considered reversal overestimations as manifestations of the c-WWI and determined the temporal-frequency tuning of the illusion for each set size. Optimal temporal frequency decreased with increasing set size. This outcome favors the discrete attentional sampling interpretation of the c-WWI, with a sampling rate for each individual stimulus dependent on the number of stimuli attended.     

Temporal binding errors are redistributed by the attentional blink

When one searches for a target among nontargets appearing in rapid serial visual presentation (RSVP), one’s errors in performance typically involve the misreporting of neighboring nontargets. Such illusory conjunctions or intrusion errors are distributed differently around the target, depending on task or stimulus variables. It is shown here that shifts in intrusion error patterns can be produced by the manipulation of attention alone. In a dual-task paradigm, the magnitude and distribution of intrusion errors changed systematically as a function of available attentional resources. Intrusion errors in RSVP tasks reflect internal capacity limitations for binding independent features. The present results support a two-stage model of RSVP target processing.     

Analysis of the perception of motion concomitant with a lateral motion of the head

This study is concerned with two questions regarding the illusory motion of objects that occurs concomitantly with motion of the head. One is whether this illusory concomitant motion, unlike the perception of real motion, is paradoxical in the sense that, although the object appears to move, it does not appear to go anywhere. The second question is whether illusory concomitant motion can be explained by errors in convergence produced by a tendency for the convergence of the eyes to displace in the direction of the resting state of convergence. Both questions receive a negative answer. In Experiment 1, it is shown that the illusory motion perceptually can add to or subtract from apparent motion resulting from real motion. In Experiment 2, it is shown that, for a binocularly viewed object at a near distance, the error in convergence (fixation disparity) is far too small to be an explanation for the illusory object motion associated with a moving head. The results of both experiments support an interpretation of illusory concomitant motion in terms of errors in the apparent distance of the stimulus object and the veridical perception of its direction.     

Temporal dynamics of anxiety-related attentional bias: is affective context a missing piece of the puzzle?

Previous research has demonstrated that anxious individuals attend to negative emotional information at the expense of other information. This is commonly referred to as attentional bias. The field has historically conceived of this process as relatively static; however, research by [Zvielli, A., Bernstein, A., &; Koster, E. H. W. (2014). Dynamics of attentional bias to threat in anxious adults: Bias towards and/or away? PLoS ONE, 9(8), e104025; Zvielli, A., Bernstein, A., &; Koster, E. H. W. (2015). Temporal dynamics of attentional bias. Clinical Psychological Science, 3(5), 772–788.], and others, challenges this assumption by demonstrating considerable temporal variability in attentional bias amongst anxious individuals. Still, the mechanisms driving these temporal dynamics are less well known. Using a modified dot-probe task, the present study examined the impact of two relevant contextual variables- affective valence and trial repetition. Affective context was instantiated by the presentation of negative versus neutral pictures before each trial, while repetition context was achieved via the presentation of the valenced pictures in either a blocked- or mixed-trial design. Results indicate that individuals with higher trait-anxiety levels were significantly more influenced by blocked presentations of negative affective information, leading to greater temporal fluctuations in attentional bias. Furthermore, our findings provide additional evidence that attentional bias is best conceptualised as dynamic and variable, and that an individual’s affective experience is one factor that regulates attentional bias dynamics. Implications relating to theoretical and methodological factors are discussed.     

Exploring the modulation of attentional capture by attentional control settings using performance and illusory line motion

Modulation of attentional capture by attentional control settings was explored using performance and phenomenology. Trials began with four figure-8s presented above, below, left, and right of fixation. Any figure-8 (or none) brightened uninformatively (cue) before presentation of either a digit target (2 or 5 made from a figure-8 by deletion) calling for a speeded identification, or a line connecting adjacent figure-8s calling for a motion judgement. Such lines are seen drawn away from an adjacent cue. Digit targets appeared only on the horizontal or vertical axes, encouraging voluntary attention to two (target-relevant) of the four figure-8s. Whereas voluntary attention reduced attentional capture from cues at taskirrelevant locations (when lines were unlikely to be presented near the task-irrelevant locations), it had no effect on motion judgements, suggesting that cue-elicited exogenous attention affects perceptual arrival times while voluntary attention prioritizes locations for further processing without affecting arrival times.     

Rapid adaptation of the vestibulo-ocular reflex and induced self-motion perception

When a rigid object moves toward the eye, it is usually perceived as being rigid. However, in the case of motion away from the eye, the motion and structure of the object are perceived nonveridically, with the percept tending to reflect the nonrigid transformations that are present in the retinal image. This difference in response to motion to and from the observer was quantified in an experiment using wire-frame computer-generated boxes which moved toward and away from the eye. Two theoretical systems are developed by which uniform three-dimensional velocity can be recovered from an expansion pattern of nonuniform velocity vectors. It is proposed that the human visual system uses two similar systems for processing motion in depth. The mechanism used for motion away from the eye produces perceptual errors because it is not suited to objects with a depth component.