Perceptual Grounding of Spatial Reference Frames in Communication and Action

Acronym: 
PESCA
Term: 
2010-05 till 2012-10
Research Areas: 
A
B
Abstract: 

Because human beings are primarily visually oriented, most of studies about space perception and representation are conducted using visual stimuli. However, in absence of vision, orientation is mainly guided by audition. Although it is known how accurate humans can be in recognizing the location of sound sources, less attention is given to the representation of auditory space. In this project we are interested in relations between spatial region concepts, their grounding in the acoustic domain and their dependency on response actions.

Methods and Research Questions: 

In our first study we investigated the basic features of the representation of egocentric auditory space, based on the following questions: (1) Are the surrounding directions of sound sources very different, or could they be clustered in terms of subjective similarity? (2) In the horizontal plane, how wide are the egocentric front, back, left and right regions?

In our first study we investigated the basic features of the representation of egocentric auditory space, based on the following questions: (1) Are the surrounding directions of sound sources very different, or could they be clustered in terms of subjective similarity? (2) In the horizontal plane, how wide are the egocentric front, back, left and right regions? (3) Is such representation affected by the response condition, that is, are the regions of auditory space represented in different sizes depending on the intended interaction with the environment? If so, which regions or directions are more susceptible to this effect?

Our second study was carried out in order to investigate the categorization pattern of the auditory space in three groups, namely: a) blind soccer players; b) blind non-athletes subjects; c) a control group of sighted subjects. Experiments were accomplished using the same methodology as in our first study, but excluding the condition of “turning to face the direction” from the acoustic-spatial task, as it showed no significant features in comparison with the remaining conditions in the first study.

We combined two methodological approaches: Structural Dimensional Analyses (SDA), in which subjects should decide if two acoustic stimuli coming from different directions are similar or not; and an acoustic- spatial task, in which participants should use predefined categories to describe the direction of the sound location in three conditions: a) looking forward; b) turning to face the direction; c) turning to face it and pointing toward the direction.
We analized the effect of the response conditions on the categorization of directions, and the sizes of "front", "back", "left" and "right" regions for each condition.
In the first study we were primarily interested in the possible differences of representation due to the response condition, and in the second study we foccused on the differences between the groups.

 

Outcomes: 

Results of the SDA indicate that the characteristics of front and back are more remarkable than those of left and right. The clusters formed at the sides included 4 directions each, while at the front and at the back regions, the clusters comprised only 2 directions. Regarding the sizes of the egocentric regions, “front” occupied the smallest area, followed by “back”, “right” and “left”. This configuration is different from the configuration of the visual space suggested by earlier studies, in which “front” is represented with larger region, because movement, manipulation of objects and perception occur primarily at this region. Differently, as auditory events occur and can be perceived in all directions, we suggest that this disparity is the reason for this divergence between the representations of visual and auditory space. Response conditions affect the representation of auditory space, especially at the sides. When participants were asked to describe the directions while facing or pointing toward the stimulus positions, they did that more thoroughly than when they performed the task while facing front. The second study is currently at the stage of data analysis.

 

 

Publications: