Biological Motion Alters Coherent Motion Perception

Perception ◽  
10.1068/p5933 ◽  
2008 ◽  
Vol 37 (12) ◽  
pp. 1783-1789 ◽  
Author(s):  
Kiyoshi Fujimoto ◽  
Akihiro Yagi
Keyword(s):  
Motion Perception ◽  
Biological Motion ◽  
Coherent Motion ◽  
Choice Procedure ◽  
Motion Coherence ◽  
Forced Choice Procedure ◽  
The Mean ◽  
Point Light ◽  
Direction Opposite ◽  
Method Of Constant Stimuli

When a movie presents a person walking, the background appears to move in the direction opposite to the person's gait. This study verified this backscroll illusion by presenting a point-light walker against a background of a random-dot cinematogram (RDC). The RDC consisted of some signal dots moving coherently either leftward or rightward among other noise dots moving randomly. The method of constant stimuli was used to vary the RDC in motion coherence from trial to trial by manipulating the direction and percentage of the signal dots. Six observers judged the perceived direction of coherent motion in a two-alternative forced-choice procedure. Response rates for coherent motion perception in the direction opposite to walking were evaluated as a function of motion coherence. The results showed that the psychometric function shifted toward the direction determined by a bias in the opposite direction to the walker. The mean threshold was about half as high as that in a control condition in which the positions of the point-lights were scrambled to impair the recognition of the walker. The results demonstrate that biological motion noticeably affects the appearance of motion coherence in the background.

scholarly journals The effect of blue light filtering lenses on speed perception

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Adiba Ali ◽  
Maitreyee Roy ◽  
Hind Saeed Alzahrani ◽  
Sieu K. Khuu
Keyword(s):  
Test Stimulus ◽  
Blue Light ◽  
Motion Perception ◽  
Unintended Consequences ◽  
Reference Stimulus ◽  
Choice Procedure ◽  
Speed Perception ◽  
Forced Choice Procedure ◽  
Perceived Speed ◽  
Method Of Constant Stimuli

AbstractBlue-light filtering lenses (BFLs) are marketed to protect the eyes from blue light that may be hazardous to the visual system. Because BFLs attenuate light, they reduce object contrast, which may impact visual behaviours such as the perception of object speed which reduces with contrast. In the present study, we investigated whether speed perception is affected by BFLs. Using a two-interval forced-choice procedure in conjunction with Method of Constant Stimuli, participants (n = 20) judged whether the perceived speed of a moving test stimulus (1.5–4.5°/s) viewed through a BFL was faster than a reference stimulus (2.75°/s) viewed through a clear lens. This procedure was repeated for 3 different BFL brands and chromatic and achromatic stimuli. Psychometric function fits provided an estimate of the speed at which both test and reference stimuli were matched. We find that the perceived speed of both chromatic and achromatic test stimuli was reduced by 6 to 20% when viewed through BFLs, and lenses that attenuated the most blue-light produced the largest reductions in perceived speed. Our findings indicate that BFLs whilst may reduce exposure to hazardous blue light, have unintended consequences to important visual behaviours such as motion perception.

scholarly journals High Ripple-Density Resolution for Discriminating Between Rippled and Nonrippled Signals: Effect of Temporal Processing or Combination Products?

2021 ◽  
Vol 25 ◽  
pp. 233121652110101
Author(s):  
Dmitry I. Nechaev ◽  
Olga N. Milekhina ◽  
Marina S. Tomozova ◽  
Alexander Y. Supin
Keyword(s):  
Low Frequency ◽  
Noise Signal ◽  
Density Variation ◽  
Choice Procedure ◽  
Masker Level ◽  
Reference Signals ◽  
Forced Choice Procedure ◽  
The Mean ◽  
Density Resolution

The goal of the study was to investigate the role of combination products in the higher ripple-density resolution estimates obtained by discrimination between a spectrally rippled and a nonrippled noise signal than that obtained by discrimination between two rippled signals. To attain this goal, a noise band was used to mask the frequency band of expected low-frequency combination products. A three-alternative forced-choice procedure with adaptive ripple-density variation was used. The mean background (unmasked) ripple-density resolution was 9.8 ripples/oct for rippled reference signals and 21.8 ripples/oct for nonrippled reference signals. Low-frequency maskers reduced the ripple-density resolution. For masker levels from −10 to 10 dB re. signal, the ripple-density resolution for nonrippled reference signals was approximately twice as high as that for rippled reference signals. At a masker level as high as 20 dB re. signal, the ripple-density resolution decreased in both discrimination tasks. This result leads to the conclusion that low-frequency combination products are not responsible for the task-dependent difference in ripple-density resolution estimates.

Effects of TMS over Premotor and Superior Temporal Cortices on Biological Motion Perception

2012 ◽  
Vol 24 (4) ◽  
pp. 896-904 ◽  
Author(s):  
Bianca Michelle van Kemenade ◽  
Neil Muggleton ◽  
Vincent Walsh ◽  
Ayse Pinar Saygin
Keyword(s):  
Motion Perception ◽  
Biological Motion ◽  
Premotor Cortex ◽  
Control Site ◽  
Object Motion ◽  
Motion Processing ◽  
False Alarms ◽  
Control Task ◽  
Biological Motion Perception ◽  
Point Light

Using MRI-guided off-line TMS, we targeted two areas implicated in biological motion processing: ventral premotor cortex (PMC) and posterior STS (pSTS), plus a control site (vertex). Participants performed a detection task on noise-masked point-light displays of human animations and scrambled versions of the same stimuli. Perceptual thresholds were determined individually. Performance was measured before and after 20 sec of continuous theta burst stimulation of PMC, pSTS, and control (each tested on different days). A matched nonbiological object motion task (detecting point-light displays of translating polygons) served as a further control. Data were analyzed within the signal detection framework. Sensitivity (d′) significantly decreased after TMS of PMC. There was a marginally significant decline in d′ after TMS of pSTS but not of control site. Criterion (response bias) was also significantly affected by TMS over PMC. Specifically, subjects made significantly more false alarms post-TMS of PMC. These effects were specific to biological motion and not found for the nonbiological control task. To summarize, we report that TMS over PMC reduces sensitivity to biological motion perception. Furthermore, pSTS and PMC may have distinct roles in biological motion processing as behavioral performance differs following TMS in each area. Only TMS over PMC led to a significant increase in false alarms, which was not found for other brain areas or for the control task. TMS of PMC may have interfered with refining judgments about biological motion perception, possibly because access to the perceiver's own motor representations was compromised.

Body Configuration Modulates the Usage of Local Cues to Direction in Biological-Motion Perception

2011 ◽  
Vol 22 (12) ◽  
pp. 1543-1549 ◽  
Author(s):  
Masahiro Hirai ◽  
Dorita H. F. Chang ◽  
Daniel R. Saunders ◽  
Nikolaus F. Troje
Keyword(s):  
Motion Perception ◽  
Biological Motion ◽  
Visual Display ◽  
Local Motion ◽  
Direction Discrimination ◽  
Biological Motion Perception ◽  
Vertical Location ◽  
Local Inversion ◽  
Point Light ◽  
Local Cues

The presence of information in a visual display does not guarantee its use by the visual system. Studies of inversion effects in both face recognition and biological-motion perception have shown that the same information may be used by observers when it is presented in an upright display but not used when the display is inverted. In our study, we tested the inversion effect in scrambled biological-motion displays to investigate mechanisms that validate information contained in the local motion of a point-light walker. Using novel biological-motion stimuli that contained no configural cues to the direction in which a walker was facing, we found that manipulating the relative vertical location of the walker’s feet significantly affected observers’ performance on a direction-discrimination task. Our data demonstrate that, by themselves, local cues can almost unambiguously indicate the facing direction of the agent in biological-motion stimuli. Additionally, we document a noteworthy interaction between local and global information and offer a new explanation for the effect of local inversion in biological-motion perception.

scholarly journals Ventral aspect of the visual form pathway is not critical for the perception of biological motion

2015 ◽  
Vol 112 (4) ◽  
pp. E361-E370 ◽  
Author(s):  
Sharon Gilaie-Dotan ◽  
Ayse Pinar Saygin ◽  
Lauren J. Lorenzi ◽  
Geraint Rees ◽  
Marlene Behrmann
Keyword(s):  
Visual Cortex ◽  
Motion Perception ◽  
Biological Motion ◽  
Form Perception ◽  
Motion Processing ◽  
Extrastriate Body Area ◽  
Biological Motion Perception ◽  
Neurobiological Substrates ◽  
Cortical Regions ◽  
Point Light

Identifying the movements of those around us is fundamental for many daily activities, such as recognizing actions, detecting predators, and interacting with others socially. A key question concerns the neurobiological substrates underlying biological motion perception. Although the ventral “form” visual cortex is standardly activated by biologically moving stimuli, whether these activations are functionally critical for biological motion perception or are epiphenomenal remains unknown. To address this question, we examined whether focal damage to regions of the ventral visual cortex, resulting in significant deficits in form perception, adversely affects biological motion perception. Six patients with damage to the ventral cortex were tested with sensitive point-light display paradigms. All patients were able to recognize unmasked point-light displays and their perceptual thresholds were not significantly different from those of three different control groups, one of which comprised brain-damaged patients with spared ventral cortex (n > 50). Importantly, these six patients performed significantly better than patients with damage to regions critical for biological motion perception. To assess the necessary contribution of different regions in the ventral pathway to biological motion perception, we complement the behavioral findings with a fine-grained comparison between the lesion location and extent, and the cortical regions standardly implicated in biological motion processing. This analysis revealed that the ventral aspects of the form pathway (e.g., fusiform regions, ventral extrastriate body area) are not critical for biological motion perception. We hypothesize that the role of these ventral regions is to provide enhanced multiview/posture representations of the moving person rather than to represent biological motion perception per se.

scholarly journals Biological Motion Perception Is Affected by Age and Cognitive Style in Children Aged 8–15

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Parisa Ghanouni ◽  
Amir Hossein Memari ◽  
Monir Shayestehfar ◽  
Pouria Moshayedi ◽  
Shahriar Gharibzadeh ◽  
...  
Keyword(s):  
Social Context ◽  
Motion Perception ◽  
Biological Motion ◽  
Independent Predictor ◽  
Cognitive Styles ◽  
Social Contexts ◽  
Developmental Changes ◽  
Action Perception ◽  
Biological Motion Perception ◽  
Point Light

The current paper aims to address the question of how biological motion perception in different social contexts is influenced by age or also affected by cognitive styles. We examined developmental changes of biological motion perception among 141 school children aged 8–15 using point-light displays in monadic and dyadic social contexts. Furthermore, the cognitive styles of participants were investigated using empathizing-systemizing questionnaires. Results showed that the age and empathizing ability strongly predicted improvement in action perception in both contexts. However the systemizing ability was an independent predictor of performance only in monadic contexts. Furthermore, accuracy of action perception increased significantly from 46.4% (SD = 16.1) in monadic to 62.5% (SD = 11.5) in dyadic social contexts. This study can help to identify the roles of social context in biological motion perception and shows that children with different cognitive styles may present different biological motion perception.

scholarly journals Perceiving Animacy From Deformation and Translation

i-Perception ◽  
2017 ◽  
Vol 8 (3) ◽  
pp. 204166951770776 ◽  
Author(s):  
Takahiro Kawabe
Keyword(s):  
Motion Perception ◽  
Biological Motion ◽  
Critical Role ◽  
Vertical Motion ◽  
Motion Vectors ◽  
Biological Motion Perception ◽  
Translation Component ◽  
Point Light ◽  
Original Motion

In a cartoon, we often receive an animacy impression from a dynamic nonanimate object, such as a sponge or a flour sack, which does not have an animal-like shape. We hypothesize that the animacy impression of a nonanimal object could stem from dynamic patterns that are possibly fundamental for biological motion perception. Here we show that observers recognize the animacy of human jump actions from the combination of deformation and translation. We extracted vertical motion vectors from the uppermost and lowermost points in point-light jumper stimuli and assigned the vectors to a uniform rectangle. The participants’ task was to rate the animacy and jump impressions for the rectangle. Results showed that both animacy and jump impressions for the rectangle movements were comparable to those for the original point-light movements. The impressions decreased for stimuli having a deformation or translation component alone, which was extracted from the original motion vectors. By mathematically simulating deformation and translation in a human jump, we also found that the temporal relation between deformation and translation plays a critical role in the determination of jump impressions but only has a moderate effect for animacy impressions. On the basis of the results, we discuss how cartoon techniques take advantage of the properties of biological motion perception.

scholarly journals Linguistic labels cue biological motion perception and misperception

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ksenija Slivac ◽  
Alexis Hervais-Adelman ◽  
Peter Hagoort ◽  
Monique Flecken
Keyword(s):  
Motion Perception ◽  
High Performance ◽  
Biological Motion ◽  
Top Down ◽  
Diagnostic Features ◽  
Biological Motion Perception ◽  
Motion Features ◽  
Point Light ◽  
Linguistic Labels ◽  
Lexical Cues

AbstractLinguistic labels exert a particularly strong top-down influence on perception. The potency of this influence has been ascribed to their ability to evoke category-diagnostic features of concepts. In doing this, they facilitate the formation of a perceptual template concordant with those features, effectively biasing perceptual activation towards the labelled category. In this study, we employ a cueing paradigm with moving, point-light stimuli across three experiments, in order to examine how the number of biological motion features (form and kinematics) encoded in lexical cues modulates the efficacy of lexical top-down influence on perception. We find that the magnitude of lexical influence on biological motion perception rises as a function of the number of biological motion-relevant features carried by both cue and target. When lexical cues encode multiple biological motion features, this influence is robust enough to mislead participants into reporting erroneous percepts, even when a masking level yielding high performance is used.

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