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Disambiguating ambiguous motion perception: what are the cues?

Piedimonte A, Woods AJ, Chatterjee A - Front Psychol (2015)

Bottom Line: Participants were consistently biased by less AMB motion cues in the environment when reporting the AMB target direction.However, when participants learned a specific association about the target motion, this acquired endogenous knowledge countered exogenous motion cues in biasing participants' perception.Taken together, our findings demonstrate that we disambiguate AMB motion using different sources of exogenous and endogenous cues, and that learned associations may be particularly salient in countering the effects of environmental cues.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, University of Turin Turin, Italy ; Department of Neurology, Center for Cognitive Neuroscience, University of Pennsylvania Philadelphia, PA, USA.

ABSTRACT
Motion perception is a fundamental feature of the human visual system. As part of our daily life we often have to determine the direction of motion, even in ambiguous (AMB) situations. These situations force us to rely on exogenous cues, such as other environmental motion, and endogenous cues, such as our own actions, or previously learned experiences. In three experiments, we asked participants to report the direction of an AMB motion display, while manipulating exogenous and endogenous sources of information. Specifically, in all three experiments the exogenous information was represented by another motion cue while the endogenous cue was represented, respectively, by movement execution, movement planning, or a learned association about the motion display. Participants were consistently biased by less AMB motion cues in the environment when reporting the AMB target direction. In the absence of less AMB exogenous motion information, participants were biased by their motor movements and even the planning of such movements. However, when participants learned a specific association about the target motion, this acquired endogenous knowledge countered exogenous motion cues in biasing participants' perception. Taken together, our findings demonstrate that we disambiguate AMB motion using different sources of exogenous and endogenous cues, and that learned associations may be particularly salient in countering the effects of environmental cues.

No MeSH data available.


Related in: MedlinePlus

Type of stimuli common to all experiments. In the ambiguous (AMB) condition both the outer circle and the inner circle were shifted by 12° to the right. In the counterclockwise condition (CCW) the outer circle was shifted by 12° to the right while the inner circle was shifted by 14° to the left. In the clockwise condition (CW) the outer circle was shifted by 12° to the right while the inner circle was shifted by 14° to the right. In all experiments both the outer and the inner circle were shifted five times per second (5 Hz). Participants were requested to judge only the rotation of the outer circle.
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Figure 2: Type of stimuli common to all experiments. In the ambiguous (AMB) condition both the outer circle and the inner circle were shifted by 12° to the right. In the counterclockwise condition (CCW) the outer circle was shifted by 12° to the right while the inner circle was shifted by 14° to the left. In the clockwise condition (CW) the outer circle was shifted by 12° to the right while the inner circle was shifted by 14° to the right. In all experiments both the outer and the inner circle were shifted five times per second (5 Hz). Participants were requested to judge only the rotation of the outer circle.

Mentions: For all experiments, the main stimuli consisted of two circles one nested within the other (see Figure 2). Stimuli were based on a stimulus created by Ilg et al. (2008). Each circle contained 15 white dots on a black background (24° between each other). The outer circle had a diameter of 19.3 cm and contained dots with a diameter of 2.2 cm. The inner circle had a diameter of 10.3 cm and contained dots with a diameter of 1.2 cm. A fixation cross was displayed in the middle of the stimulus (see Figure 2). During each trial of every experiment, different frames of the circles were displayed at a frequency of 5 Hz, rotated by a specific angle: this shift between frames gave the participant the perception of a continuous rotation. The outer circle always rotated by +12° in each frame. In a pilot study (n = 12) we asked participants, in 30 trials, to tell their perceived direction of a circle with the same structure of the outer circle in our experiments (15 dots, 24° between each other, shifted by +12° at 5 Hz). In this pilot study we confirmed that a +12° shift resulted in an AMB (either clockwise, CW or counterclockwise, CCW) perception of motion (mean CW perceptions = 16.08) confirming early results with this type of stimulus (Ilg et al., 2008). In all the experiments, the main request to the participants was: “in which direction do you perceive the outer circle to be rotating?” The movement of the inner circle represented exogenous information from the environment. The circular motion was selected as the exogenous cue for two reasons. First, motion is a salient visual characteristic, perhaps more so than color, intensity, and orientation (Itti, 2005). Second, since the exogenous cue and the stimulus to be judged were similar (see Figure 2) we expected participants to easily group them together, following the classic Gestalt rule of similarity (Torodovic, 2008) even when instructed to ignore the inner circle. Changing the angular displacement of the inner circle’s dots created three perceived rotations: an AMB rotation (equal to the outer circle’s rotation), a CW rotation and a CCW rotation. These three inner circle rotations were used to bias the perception of the outer circle’s rotation. The inner circle’s rotation was AMB in one third of the trials using the same shifting angle and frequency as the outer circle’s rotation (i.e., shifted by 12° to the right in each frame at 5 Hz). To choose an angle that could create a rotation perceived as CW, in a second pilot study (n = 12) we asked participants to tell their perceived direction of a circle with the same structure of the outer circle in our experiments (15 dots, 24° between each other) shifted by different angles (+12°, +14°, -14°) at 5 Hz, with 20 trials for each angle (total trials = 60). In this second pilot study we first confirmed that a +12° results in an AMB bias (mean CW perceptions = 10.57) while we found that rotating the 15 dots circle by 14° to the right with the same frequency of 5 Hz, created a strong CW bias (mean CW perceptions ± SE = 17.42) and the opposite rotation, that is 14° to the left, created a strong CCW bias (mean CW perceptions = 2.42). Using these two angles (+14° and -14°): in other third of the trials the inner circle’s rotation was rendered to be perceived as CW (angle = +14°, freq = 5 Hz) and in the last third of the trials perceived as CCW (angle = -14°, freq = 5 Hz).


Disambiguating ambiguous motion perception: what are the cues?

Piedimonte A, Woods AJ, Chatterjee A - Front Psychol (2015)

Type of stimuli common to all experiments. In the ambiguous (AMB) condition both the outer circle and the inner circle were shifted by 12° to the right. In the counterclockwise condition (CCW) the outer circle was shifted by 12° to the right while the inner circle was shifted by 14° to the left. In the clockwise condition (CW) the outer circle was shifted by 12° to the right while the inner circle was shifted by 14° to the right. In all experiments both the outer and the inner circle were shifted five times per second (5 Hz). Participants were requested to judge only the rotation of the outer circle.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4496557&req=5

Figure 2: Type of stimuli common to all experiments. In the ambiguous (AMB) condition both the outer circle and the inner circle were shifted by 12° to the right. In the counterclockwise condition (CCW) the outer circle was shifted by 12° to the right while the inner circle was shifted by 14° to the left. In the clockwise condition (CW) the outer circle was shifted by 12° to the right while the inner circle was shifted by 14° to the right. In all experiments both the outer and the inner circle were shifted five times per second (5 Hz). Participants were requested to judge only the rotation of the outer circle.
Mentions: For all experiments, the main stimuli consisted of two circles one nested within the other (see Figure 2). Stimuli were based on a stimulus created by Ilg et al. (2008). Each circle contained 15 white dots on a black background (24° between each other). The outer circle had a diameter of 19.3 cm and contained dots with a diameter of 2.2 cm. The inner circle had a diameter of 10.3 cm and contained dots with a diameter of 1.2 cm. A fixation cross was displayed in the middle of the stimulus (see Figure 2). During each trial of every experiment, different frames of the circles were displayed at a frequency of 5 Hz, rotated by a specific angle: this shift between frames gave the participant the perception of a continuous rotation. The outer circle always rotated by +12° in each frame. In a pilot study (n = 12) we asked participants, in 30 trials, to tell their perceived direction of a circle with the same structure of the outer circle in our experiments (15 dots, 24° between each other, shifted by +12° at 5 Hz). In this pilot study we confirmed that a +12° shift resulted in an AMB (either clockwise, CW or counterclockwise, CCW) perception of motion (mean CW perceptions = 16.08) confirming early results with this type of stimulus (Ilg et al., 2008). In all the experiments, the main request to the participants was: “in which direction do you perceive the outer circle to be rotating?” The movement of the inner circle represented exogenous information from the environment. The circular motion was selected as the exogenous cue for two reasons. First, motion is a salient visual characteristic, perhaps more so than color, intensity, and orientation (Itti, 2005). Second, since the exogenous cue and the stimulus to be judged were similar (see Figure 2) we expected participants to easily group them together, following the classic Gestalt rule of similarity (Torodovic, 2008) even when instructed to ignore the inner circle. Changing the angular displacement of the inner circle’s dots created three perceived rotations: an AMB rotation (equal to the outer circle’s rotation), a CW rotation and a CCW rotation. These three inner circle rotations were used to bias the perception of the outer circle’s rotation. The inner circle’s rotation was AMB in one third of the trials using the same shifting angle and frequency as the outer circle’s rotation (i.e., shifted by 12° to the right in each frame at 5 Hz). To choose an angle that could create a rotation perceived as CW, in a second pilot study (n = 12) we asked participants to tell their perceived direction of a circle with the same structure of the outer circle in our experiments (15 dots, 24° between each other) shifted by different angles (+12°, +14°, -14°) at 5 Hz, with 20 trials for each angle (total trials = 60). In this second pilot study we first confirmed that a +12° results in an AMB bias (mean CW perceptions = 10.57) while we found that rotating the 15 dots circle by 14° to the right with the same frequency of 5 Hz, created a strong CW bias (mean CW perceptions ± SE = 17.42) and the opposite rotation, that is 14° to the left, created a strong CCW bias (mean CW perceptions = 2.42). Using these two angles (+14° and -14°): in other third of the trials the inner circle’s rotation was rendered to be perceived as CW (angle = +14°, freq = 5 Hz) and in the last third of the trials perceived as CCW (angle = -14°, freq = 5 Hz).

Bottom Line: Participants were consistently biased by less AMB motion cues in the environment when reporting the AMB target direction.However, when participants learned a specific association about the target motion, this acquired endogenous knowledge countered exogenous motion cues in biasing participants' perception.Taken together, our findings demonstrate that we disambiguate AMB motion using different sources of exogenous and endogenous cues, and that learned associations may be particularly salient in countering the effects of environmental cues.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, University of Turin Turin, Italy ; Department of Neurology, Center for Cognitive Neuroscience, University of Pennsylvania Philadelphia, PA, USA.

ABSTRACT
Motion perception is a fundamental feature of the human visual system. As part of our daily life we often have to determine the direction of motion, even in ambiguous (AMB) situations. These situations force us to rely on exogenous cues, such as other environmental motion, and endogenous cues, such as our own actions, or previously learned experiences. In three experiments, we asked participants to report the direction of an AMB motion display, while manipulating exogenous and endogenous sources of information. Specifically, in all three experiments the exogenous information was represented by another motion cue while the endogenous cue was represented, respectively, by movement execution, movement planning, or a learned association about the motion display. Participants were consistently biased by less AMB motion cues in the environment when reporting the AMB target direction. In the absence of less AMB exogenous motion information, participants were biased by their motor movements and even the planning of such movements. However, when participants learned a specific association about the target motion, this acquired endogenous knowledge countered exogenous motion cues in biasing participants' perception. Taken together, our findings demonstrate that we disambiguate AMB motion using different sources of exogenous and endogenous cues, and that learned associations may be particularly salient in countering the effects of environmental cues.

No MeSH data available.


Related in: MedlinePlus