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How category structure influences the perception of object similarity: the atypicality bias.

Tanaka JW, Kantner J, Bartlett M - Front Psychol (2012)

Bottom Line: If similarity judgments are guided purely by their physical properties, the morph should be perceived to be equally similar to its typical parent as its atypical parent.In this framework, atypical stimuli are located in a sparser region of the space where there is less competition for recognition and therefore, these representations capture a broader range of inputs.These results suggest that the perceived likeness of an object is influenced by the organization of surrounding exemplars in the category space.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, University of Victoria Victoria, BC, Canada.

ABSTRACT
Why do some faces appear more similar than others? Beyond structural factors, we speculate that similarity is governed by the organization of faces located in a multi-dimensional face space. To test this hypothesis, we morphed a typical face with an atypical face. If similarity judgments are guided purely by their physical properties, the morph should be perceived to be equally similar to its typical parent as its atypical parent. However, contrary to the structural prediction, our results showed that the morph face was perceived to be more similar to the atypical face than the typical face. Our empirical studies show that the atypicality bias is not limited to faces, but extends to other object categories (birds) whose members share common shape properties. We also demonstrate atypicality bias is malleable and can change subject to category learning and experience. Collectively, the empirical evidence indicates that perceptions of face and object similarity are affected by the distribution of stimuli in a face or object space. In this framework, atypical stimuli are located in a sparser region of the space where there is less competition for recognition and therefore, these representations capture a broader range of inputs. In contrast, typical stimuli are located in a denser region of category space where there is increased competition for recognition and hence, these representation draw a more restricted range of face inputs. These results suggest that the perceived likeness of an object is influenced by the organization of surrounding exemplars in the category space.

No MeSH data available.


Related in: MedlinePlus

Examples of the atypical and typical female and male faces and their 50/50 morph faces used in the Tanaka et al. (1998) study.
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Figure 2: Examples of the atypical and typical female and male faces and their 50/50 morph faces used in the Tanaka et al. (1998) study.

Mentions: Tanaka et al. (1998) used a delayed match-to-sample task to test the assumption of the attractor field model that distinctive category members possess larger attractor fields than typical members. Tanaka et al. (1998) identified a set of eight typical and eight distinctive faces through pilot testing and morphed each typical face with each distinctive face of the same gender (Figure 2). To construct a morph of the atypical and typical parent faces, corresponding control points were identified on the two parent images (e.g., the corner of the left eye on Parent Face Image 1 and Parent Face Image 2). The number of control points for facial features were kept constant, with 12 points on the mouth, 7 points on each eye, 6 points on the nose, 5 points on each eyebrow, and 22 points for the outline of the face. According to the level of morphing, new control points for the morph face were defined by moving the specified distance along the vector connecting the control points in parent images. The locations of intervening pixels were linearly interpolated across the surface based on the position of the nearest control point (Wolberg, 1990). A fade process was then employed in which the brightness values for each corresponding pixel were weighted according to the contribution of each parent image.


How category structure influences the perception of object similarity: the atypicality bias.

Tanaka JW, Kantner J, Bartlett M - Front Psychol (2012)

Examples of the atypical and typical female and male faces and their 50/50 morph faces used in the Tanaka et al. (1998) study.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3368386&req=5

Figure 2: Examples of the atypical and typical female and male faces and their 50/50 morph faces used in the Tanaka et al. (1998) study.
Mentions: Tanaka et al. (1998) used a delayed match-to-sample task to test the assumption of the attractor field model that distinctive category members possess larger attractor fields than typical members. Tanaka et al. (1998) identified a set of eight typical and eight distinctive faces through pilot testing and morphed each typical face with each distinctive face of the same gender (Figure 2). To construct a morph of the atypical and typical parent faces, corresponding control points were identified on the two parent images (e.g., the corner of the left eye on Parent Face Image 1 and Parent Face Image 2). The number of control points for facial features were kept constant, with 12 points on the mouth, 7 points on each eye, 6 points on the nose, 5 points on each eyebrow, and 22 points for the outline of the face. According to the level of morphing, new control points for the morph face were defined by moving the specified distance along the vector connecting the control points in parent images. The locations of intervening pixels were linearly interpolated across the surface based on the position of the nearest control point (Wolberg, 1990). A fade process was then employed in which the brightness values for each corresponding pixel were weighted according to the contribution of each parent image.

Bottom Line: If similarity judgments are guided purely by their physical properties, the morph should be perceived to be equally similar to its typical parent as its atypical parent.In this framework, atypical stimuli are located in a sparser region of the space where there is less competition for recognition and therefore, these representations capture a broader range of inputs.These results suggest that the perceived likeness of an object is influenced by the organization of surrounding exemplars in the category space.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, University of Victoria Victoria, BC, Canada.

ABSTRACT
Why do some faces appear more similar than others? Beyond structural factors, we speculate that similarity is governed by the organization of faces located in a multi-dimensional face space. To test this hypothesis, we morphed a typical face with an atypical face. If similarity judgments are guided purely by their physical properties, the morph should be perceived to be equally similar to its typical parent as its atypical parent. However, contrary to the structural prediction, our results showed that the morph face was perceived to be more similar to the atypical face than the typical face. Our empirical studies show that the atypicality bias is not limited to faces, but extends to other object categories (birds) whose members share common shape properties. We also demonstrate atypicality bias is malleable and can change subject to category learning and experience. Collectively, the empirical evidence indicates that perceptions of face and object similarity are affected by the distribution of stimuli in a face or object space. In this framework, atypical stimuli are located in a sparser region of the space where there is less competition for recognition and therefore, these representations capture a broader range of inputs. In contrast, typical stimuli are located in a denser region of category space where there is increased competition for recognition and hence, these representation draw a more restricted range of face inputs. These results suggest that the perceived likeness of an object is influenced by the organization of surrounding exemplars in the category space.

No MeSH data available.


Related in: MedlinePlus