Representation of dynamic events triggered by motion lines and static human postures

Are We Moving Too Fast?: Representation of Speed in Static Images

Despite pictures being static representations, they use various cues to suggest dynamic motion. To investigate the effectiveness of different motion cues in conveying speed in static images, we conducted 3 experiments. In Experiment 1, we compared subjective speed ratings given for motion lines trailing behind movers, suppletion lines replacing parts of the movers and backfixing lines set in the background against the baseline of having no extra cue. Experiment 2 was a replication of the first experiment with an addition of several motion lines considering the effect of quantity on conveyed speed. Experiment 3 then examined the actual time assessments of each cue and bare objects indicated for movers to complete their paths. Our results showed that motion cues vary in their effectiveness in depicting speed, with some influence from proficiency in reading manga. Motion lines, which index the path being traversed, remained less effective than suppletion and backfixing lines, which we argue encode the speed component of motion rather than directionality. However, adding more motion lines intensified the perceived speed of the movers. These static cues also influenced the actual time durations individuals indicated for fictitious motion events, in line with the subjective speed ratings. Altogether, our results suggest that different aspects of motion can be captured by different cues, and that the effectiveness of cues might be modulated by exposure to such patterns, in line with the premises of a visual lexicon view.

Going forward: perceptual bias for forward-facing motion in chimpanzees

When a row of objects surrounded by a frame suddenly shifts a certain distance so that part of the row is occluded by the frame, humans perceive ambiguous apparent motion either to the left or the right. However, when the objects have "directionality," humans perceive them as moving forward in the direction in which they are pointing, which is termed forward-facing motion bias. In the present study, five experiments were conducted to address whether, and if so how, physical properties or prior knowledge about the objects affected the perception of their apparent motion in two juvenile chimpanzees (Pan troglodytes). In experiment 1, the chimpanzees did not show a clear forward-facing bias in judging the direction of motion when directed triangles were presented, whereas the human participants did. In contrast, when pictures of the lateral view of chimpanzees with quadrupedal postures were shown, there was a clear bias for going "forward" with regards to the side with the head (experiment 2). We presented pictures of dogs looking back to explore what features caused the forward-facing motion bias (experiment 3). Chimpanzees did not show any bias for these stimuli, suggesting that the direction of the head and body interactively affected the perceptual bias. Experiment 4 tested the role of the head and found that only the lateral view of the heads of chimpanzees or humans caused the bias (experiment 4). Additional tests also showed that the chimpanzees could not solve the task based only on the direction of the stimuli without motion (experiment 5). These results indicate that the perception of motion in the chimpanzees was affected by the biological features of the stimuli, suggesting their prior knowledge of the "body" from a biological (morphological and kinetic) perspective.

Linguistic typology of motion events in visual narratives

Languages use different strategies to encode motion. Some use particles or "satellites" to describe a path of motion (Satellite-framed or S-languages like English), while others typically use the main verb to convey the path information (Verb-framed or V-languages like French). We here ask: might this linguistic variation lead to differences in the way paths are depicted in visual narratives like comics? We analyzed a corpus of 85 comics originally created by speakers of S-languages (comics from the United States, China, Germany) and V-languages (France, Japan, Korea) for both their depictions of path segments (source, route, and goal) and the visual cues signaling these paths and manner information (e.g., motion lines and postures). Panels from S-languages depicted more path segments overall, especially routes, than those from V-languages, but panels from V-languages more often isolated path segments into their own panels. Additionally, comics from S-languages depicted more motion cues than those from V-languages, and this linguistic typology also interacted with panel framing. Despite these differences across typological groups, analysis of individual countries' comics showed more nuanced variation than a simple S-V dichotomy. These findings suggest a possible influence of spoken language structure on depicting motion events in visual narratives and their sequencing.

Pupillary response to real, illusory, and implied motion

The perception of moving objects (real motion) is a critical function for interacting with a dynamic environment. Motion perception can be also induced by particular structural features of static images (illusory motion) or by photographic images of subjects in motion (implied motion, IM). Many cortical areas are involved in motion processing, particularly the medial temporal cortical area (MT), dedicated to the processing of real, illusory, and implied motion. Recently, there has been a growing interest in the influence of high-level visual processes on pupillary responses. However, just a few studies have measured the effect of motion processing on the pupil, and not always with consistent results. Here we systematically investigate the effects of real, illusory, and implied motion on the pupil diameter for the first time, by showing different types of stimuli (movies, illusions, and photos) with the same average luminance to the same observers. We find different pupillary responses depending on the nature of motion. Real motion elicits a larger pupillary dilation than IM, which in turn induces more dilation than control photos representing static subjects (No-IM). The pupil response is sensitive even to the strength of IM, as photos with enhanced IM (blur, motion streaks, speed lines) induce larger dilation than simple freezed IM (subjects captured in the instant they are moving). Also, the subject represented in the stimulus matters: human figures are interpreted as more dynamic and induce larger dilation than objects/animals. Interestingly, illusory motion induces much less dilation than all the other motion categories, despite being seen as moving. Overall, pupil responses depend on the individual perception of dynamicity, confirming that the pupil is modulated by the subjective interpretation of complex stimuli. We argue that the different pupillary responses to real, illusory, and implied motion reflect the top-down modulations of different cortical areas involved in their processing.

The notion of the motion: the neurocognition of motion lines in visual narratives

Motion lines appear ubiquitously in graphic representation to depict the path of a moving object, most popularly in comics. Some researchers have argued that these graphic signs directly tie to the "streaks" appearing in the visual system when a viewer tracks an object (Burr, 2000), despite the fact that previous studies have been limited to offline measurements. Here, we directly examine the cognition of motion lines by comparing images in comic strips that depicted normal motion lines with those that either had no lines or anomalous, reversed lines. In Experiment 1, shorter viewing times appeared to images with normal lines than those with no lines, which were shorter than those with anomalous lines. In Experiment 2, measurements of event-related potentials (ERPs) showed that, compared to normal lines, panels with no lines elicited a posterior positivity that was distinct from the frontal positivity evoked by anomalous lines. These results suggested that motion lines aid in the comprehension of depicted events. LORETA source localization implicated greater activation of visual and language areas when understanding was made more difficult by anomalous lines. Furthermore, in both experiments, participants' experience reading comics modulated these effects, suggesting motion lines are not tied to aspects of the visual system, but rather are conventionalized parts of the "vocabulary" of the visual language of comics.

Implied motion perception from a still image in infancy

Visual motion perception can arise from non-directional visual stimuli, such as still images (implied motion, cf. Kourtzi, Trends Cogn Sci 8:47-49, 2004). We tested 5- to 8-month-old infants' implied motion perception with two experiments using the forced-choice preferential looking method. Our results indicated that a still image of a person running toward either the left or right side significantly enhanced infants' visual preference for a visual target that consistently appeared on the same side as the running direction (the run condition in Experiment 1). Such enhanced visual preference disappeared in response to an image of the same person standing and facing the left/right side (the stand condition in Experiment 1), an image of the running figure covered with a set of opaque rectangles (the block condition in Experiment 2) (Gervais et al. in Atten Percept Psychophys 72:1437-1443, 2010), and an image of the inverted running figure (the inversion condition in Experiment 3). These results suggest that only the figure that implied dynamic body motion shifted the infants' visual preference to the same direction as the implied running action. These findings demonstrate that even infants as young as 5 to 8 months old are sensitive to the implied motion of static figures.

The Effect of Motion Lines on Apparent-Motion Correspondence under Dichoptic Presentation

Motion lines enhance the impression of motion when viewing static/dynamic images. I investigated the binocularity of the motion-enhancing effect in an ambiguous apparent-motion display. Even in the dichoptic presentation condition, the effect of motion lines on apparent-motion correspondence was as strong as that in the monoptic condition. Additionally, there were no effects of stereo-depth separation. These results suggest that the effect of motion lines arises from a higher-level motion-processing mechanism that occurs after integrating information from both eyes.

Motion impressions enhanced by converging motion lines

We investigated how motion lines drawn in the background of a running human silhouette affect motion impressions of a runner in a static image. Observers evaluated the strength and direction of motion impression. The results show that parallel lines do not enhance frontoparallel motion impressions, while converging lines do so in an in-depth direction. This is a counter-example to the hypothesis that motion lines in the background represent motion streaks of the background when one visually tracks a moving object.

New Motion Illusion Caused by Pictorial Motion Lines

Motion lines (MLs) are a pictorial technique used to represent object movement in a still picture. This study explored how MLs contribute to motion perception. In Experiment 1, we reported the creation of a motion illusion caused by MLs: random displacements of objects with MLs on each frame were perceived as unidirectional global motion along the pictorial motion direction implied by MLs. In Experiment 2, we showed that the illusory global motion in the peripheral visual field captured the perceived motion direction of random displacement of objects without MLs in the central visual field, and confirmed that the results in Experiment 1 did not stem simply from response bias, but resulted from perceptual processing. In Experiment 3, we showed that the spatial arrangement of orientation information rather than ML length is important for the illusory global motion. Our results indicate that the ML effect is based on perceptual processing rather than response bias, and that comparison of neighboring orientation components may underlie the determination of pictorial motion direction with MLs.