Observing expertise-related actions leads to perfect time flow estimations.

The estimation of the time of exposure of a picture portraying an action increases as a function of the amount of movement implied in the action represented. This effect suggests that the perceiver creates an internal embodiment of the action observed as if internally simulating the entire movement sequence. Little is known however about the timing accuracy of these internal action simulations, specifically whether they are affected by the level of familiarity and experience that the observer has of the action. In this study we asked professional pianists to reproduce different durations of exposure (shorter or longer than one second) of visual displays both specific (a hand in piano-playing action) and non-specific to their domain of expertise (a hand in finger-thumb opposition and scrambled-pixels) and compared their performance with non-pianists. Pianists outperformed non-pianists independently of the time of exposure of the stimuli; remarkably the group difference was particularly magnified by the pianists' enhanced accuracy and stability only when observing the hand in the act of playing the piano. These results for the first time provide evidence that through musical training, pianists create a selective and self-determined dynamic internal representation of an observed movement that allows them to estimate precisely its temporal duration

Inferring the direction of implied motion depends on visual awareness

Visual awareness of an event, object, or scene is, by essence, an integrated experience, whereby different visual features composing an object (e.g., orientation, color, shape) appear as an unified percept and are processed as a whole. Here, we tested in human observers whether perceptual integration of static motion cues depends on awareness by measuring the capacity to infer the direction of motion implied by a static visible or invisible image under continuous flash suppression. Using measures of directional adaptation, we found that visible but not invisible implied motion adaptors biased the perception of real motion probes. In a control experiment, we found that invisible adaptors implying motion primed the perception of subsequent probes when they were identical (i.e., repetition priming), but not when they only shared the same direction (i.e., direction priming). Furthermore, using a model of visual processing, we argue that repetition priming effects are likely to arise as early as in the primary visual cortex. We conclude that although invisible images implying motion undergo some form of nonconscious processing, visual awareness is necessary to make inferences about motion direction

Semantic and emotional content of imagined representations in human occipitotemporal cortex.

Mental imagery is a critical cognitive function, clinically important, but poorly understood. When visual objects are perceived, many of their sensory, semantic and emotional properties are represented in occipitotemporal cortex. Visual imagery has been found to activate some of the same brain regions, but it was not known what properties are re-created in these regions during imagery. We therefore examined the representation during imagery for two stimuli in depth, by comparing the pattern of fMRI response to the patterns evoked by the perception of 200 diverse objects chosen to de-correlate their properties. Real-time, adaptive stimulus selection allowed efficient sampling of this broad stimulus space. Our experiments show that occipitotemporal cortex, which encoded sensory, semantic and emotional properties during perception, can robustly represent semantic and emotional properties during imagery, but that these representations depend on the object being imagined and on individual differences in style and reported vividness of imagery

RELATIONS BETWEEN APPARENT MOVEMENT AND EYE ACTIVITIES : II. Detailed analyses of smoothness, coherence, and dimensionality of perceived motion.

We examined the relationships between apparent motion illusion and eye movements. Six subjects were asked to report smoothness, coherence, and dimentionality of long-range apparent motion under instructions of (a) fixating their gaze to a center point of visual field, and (b) shifting their gaze saccadically to a point where the stimulus was presented. Three kinds of eye activities, fixation, saccadic eye movement, and eye blink were identified, and a ratio of successful shifts of their gaze to the stimulus-presented-point to total numbers of eye movement was calculated. Under the instruction of fixating-gaze, estimated smoothness was significantly greater than that under the shifting-gaze when the stimulus onset frequency was 3.0 Hz. Estimated coherence and dimentionality did not differentiate between fixating-gaze and shifting-gaze conditions, showing that coherence increased monotonically and dimentionality varied as inverted U-shape as a function of the onset frequency. The results suggest that eye gazing alters smoothness of apparent motion, and motion perception may be influlenced by the oculomotor control. The mechanism of motion perception is discussed in relation to the present results and recent works.Article人文科学論集. 人間情報学科編 41: 47-60(2007)departmental bulletin pape

Bewegung auf Bildern und deren Effekt auf nachfolgende Reize

Bilder mit Bewegung werden in mancherlei ähnlich verarbeitet wie reale Bewegung (siehe u. a. David und Senior, 2000). Freyd fand 1983 heraus, dass man eine auf Bildern dargestellte Bewegung im Geiste weiterdenkt. Im Sinne des Hinweisreizparadigmas von Posner (1980) wurde in der dargestellten Studie postuliert, dass Bilder mit Bewegung einen Einfluss auf die Wahrnehmung nachfolgender Reize haben. Reize, die in der Bewegungsrichtung liegen, sollten schneller erkannt werden als Reize, die sich auf der anderen Seite der Bewegung befinden. Zu diesem Zweck wurden Bilder mit Bewegungen von links nach rechts und von rechts nach links untersucht. Diese Bilder waren teilweise Fotos, teilweise Kunstwerke. Jedes Bild wurde einmal 100 und einmal 500 ms gezeigt. Nach jedem Bild erschien ein Kreis, auf den die VersuchsteilnehmerInnen so schnell wie möglich mit einem Tastendruck reagieren sollten. Es zeigte sich, dass es bei Bildern aus der Kunst keinen Bewegungseffekt gibt.Eine Besonderheit von Kunstwerken ist, dass sie über die Realität hinaus gehen. Sie müssen die Wirklichkeit also nicht wirklichkeitsgetreu abbilden. Auch Bilder, die von rechts nach links zeigen, ziehen keinen Bewegungseffekt nach sich. Einzig reale Bilder, deren Bewegung von links nach rechts erfolgt, ziehen kürzere Reaktionszeiten nach sich, wenn der Kreis in der Bewegungsrichtung liegt. Diese Richtung entspricht der Lese-undSchreibrichtung unserer Kultur. Lesen und schreiben wirkt also wie Training, das uns für eine eingefrorene Bewegung von links nach rechts sensibel macht.Perception of pictures with implied motion is similar to perception of real motion(David & Senior, 2000). In 1983 Freyd found out that there is a mental representation of movement also if it is shown on pictures. According to the spatial-cueing-paradigm (Posner, 1980) the hypothesis of this study says, images with implied motion have an impact on following stimuli. Stimuli that are presented in the direction the movement points to should be recognized faster than stimuli that are presented at the beginning of the movement. The implied motion of the analyzed images leads either from left to right of from right to left. The images were partly photos partly artworks. Every picture was presented twice, one time for 100 ms, one time for 500 ms. After every picture a circle was shown. The participants had to react as fast as possible to it. The implied motion on artworks had no effect. Images of artworks are special, because they do not have to be realistic. They do not have to represent reality exactly. That is why recognition of movement is difficult. Implied motion that points to the left has no effect either. Only photos with implied motion showing to the right lead to faster reaction. It is the direction of reading and writing in our culture. Reading and writing is like training that makes us sensitive for implied motion from left to right

Delayed Response to Animate Implied Motion in Human Motion Processing Areas

Viewing static photographs of objects in motion evokes higher fMRI activation in the human medial temporal complex (MT+) than looking at similar photographs without this implied motion. As MT+ is traditionally thought to be involved in motion perception (and not in form perception), this finding suggests feedback from object-recognition areas onto MT+. To investigate this hypothesis, we recorded extracranial potentials evoked by the sight of photographs of biological agents with and without implied motion. The difference in potential between responses to pictures with and without implied motion was maximal between 260 and 400 msec after stimulus onset. Source analysis of this difference revealed one bilateral, symmetrical dipole pair in the occipital lobe. This area also showed a response to real motion, but approximately 100 msec earlier than the implied motion response. The longer latency of the implied motion response in comparison to the real motion response is consistent with a feedback projection onto MT+ following object recognition in higher-level temporal areas

The role of human motion processing complex, MT+, during sustained perception and attention

Thesis advisor: Scott D. SlotnickThe overarching aim of this dissertation is to examine the role of human motion processing complex, MT+ during sustained perception and attention. MT+ is comprised of sub-region MT, which processes motion in the contralateral visual field (i.e., left hemisphere MT processes motion in the right visual field and vice versa), and sub-region MST, which processes motion in both the contralateral and ipsilateral visual fields. Whereas previous transcranial magnetic stimulation (TMS) research has provided compelling evidence that region MT+ is necessary for low-level motion processing, Chapter 1 describes an experiment testing whether the sub-region MT is necessary for contralateral low-level motion processing. Chapter 2 describes an experiment that dissociates low-level sensory attentional modulation in MT+ from high-level attentional control processing in the parietal cortex (i.e., during sustained attention). Chapter 3 describes an experiment investigating the role of MT+ during aesthetic processing when viewing visual art. Importantly, this experiment tests whether the aesthetic is tied to not only low-level motion processing in MT+ but also high-level processing in frontal regions. Taken together, the results across the three experiments provide novel evidence for the role of MT+ during low-level motion processing during sustained perception and attention. Moreover, these low-level motion processing effects together with the observed high-level processes in frontal-parietal regions provide neural mechanisms for the cognitive processes of sustained perception and attention.Thesis (PhD) — Boston College, 2012.Submitted to: Boston College. Graduate School of Arts and Sciences.Discipline: Psychology

Influenze fenomeniche nella mislocalizzazione della posizione iniziale di uno stimolo in movimento

2011/2012In questo lavoro di tesi si prenderà in esame un effetto legato alla percezione del movimento e conosciuto con il nome di Effetto Fröhlich in onore di colui che nel 1923 lo studiò per la prima volta in maniera sistematica. Percepire la posizione degli oggetti nell’ambiente è senza dubbio uno degli scopi più importanti del sistema visivo. Tuttavia, quando gli oggetti sono in movimento la localizzazione della loro posizione può risultare più difficoltosa e può essere caratterizzata da piccoli ma consistenti errori definiti mislocalizzazioni spazio-temporali. Tali errori possono coinvolgere sia la localizzazione della posizione iniziale dello stimolo in movimento (Onset) sia la posizione finale dello stesso (Offset). Nel 1930 uno studioso, Fröhlich, osserverò che se a degli osservatori si chiedeva di identificare la posizione iniziale di uno stimolo in movimento questi tendevano a identificarla non nella posizione reale, ma in una posizione spostata nella direzione del movimento. Tale errore di localizzazione fu definito Fröhlich effect. Tutte le interpretazioni prevedevano l’influenza di fattori fisiologici nella spiegazione del fenomeno. Tuttavia ciò che emerge dai risultati degli esperimenti presentati in questo lavoro è che anche fattori fenomenici possono avere una qualche influenza sulla grandezza dell’errore. L’effetto sembra essere influenzato dalle caratteristiche dell’oggetto in movimento e dalle caratteristiche del contesto all’interno del quale gli stimoli si spostano.XXV - Ciclo198

Neural Coding of Real and Implied Motion in the Human Brain

Perceiving and processing visual motion is crucial for all animals, including humans. Brain regions in the human brain that are responsive to real motion have been extensively studied with different neuroimaging methods. However, the neural codes that are related to real motion have been primarily addressed using highly reductionist and mostly artificial motion stimuli, mostly using so-called random dot kinematograms. Studies using more natural forms of motion that the brain evolved and developed to deal with are comparably rare. Moreover, real, physical motion is not the only type of stimulus that induces motion perception in humans. Implied motion stimuli also induce motion perception although the stimuli do not carry physical motion information. Implied motion stimuli are for example still images containing a snap-shot of an object in motion. Various contextual cues mediate the percept of motion, including the context of the object in its background, and in particular the object composition and its axial position in the image that mediate both, the impression of implied motion as well as its direction. This means that at the neural level, object processing must be used to generate the implied motion percept. The work described in this thesis investigated the neural coding of real and implied motion in the human brain. The investigation was done using functional brain imaging of human adults and data were collected with a 3-Tesla MRI scanner while the participants viewed a variety of distinct visual stimuli. The visual stimuli contained directional real and implied motion and were created specifically for this study. For real motion stimuli, the aim of was to engage a maximal number of directionally selective units, in order to maximize the overlap to the subset of units potentially involved in coding implied motion. Hence, real motion stimuli were created such that the static component frames had natural image statistics (known to activate neurons more effectively) by using Fourier-scrambled natural images, and motion was presented at a wide range of motion velocities. Similarly, implied motion stimuli were derived from photographs of natural scenes. They were created by placing objects such as airplanes, birds, cars, or snapshots of walking humans on a set of contextual background images such as skylines or streets. For both, real motion and implied motion, stimuli for four directions were created: forwards and backwards,and left- and rightwards