L6: Face Perception, Depth Perception

Face Recognition and Perception

  • Overview of face production and recognition by components (RBC).

  • Definition of geons: Simple geometrical shapes used in object recognition.

    • Example: A brick having three parallel edges that are invariant to viewpoint changes.

  • Discussion of subordinate, basic, and superordinate levels of categorization.

    • Subordinate level: Highly specific recognition (e.g., recognizing a specific person's face).

    • Basic level: General category (e.g., identifying an animal as a dog).

  • Exploration of expertise in face recognition and the importance of metric properties in facial features.

    • Example: Celebrity recognition highlighted among varied faces.

  • Holistic processing of faces:

    • Unlike other objects, faces are recognized as wholes rather than parts.

  • Inverted Face Perception:

    • Difficulty in recognizing features of inverted faces, emphasizing holistic processing.

    • Demonstrated through class activity with disturbing vs. normal face images to illustrate this phenomenon.

Behavioral Studies in Face Recognition

  • Description of experiments using behavioral studies to analyze face recognition skills:

    • Training participants on unique features (e.g., different shaped noses) in fictional individuals.

    • Comparison of recognition performance between isolated features and features within context.

  • Result: Better memory performance with faces presented as wholes rather than individual features.

Neurophysiological Evidence

  • Study of neural activity related to face processing during surgical procedures:

    • Recording action potentials from various parts of the brain.

  • Discussion on face-selective areas with increased neural responses observed in these areas when subjects viewed faces compared to cars or other objects.

  • Discovery of Prosopagnosia: A condition characterized by the inability to recognize faces due to damage in the ventral stream of the cerebral cortex.

  • Evidence of brain damage and the impact on facial recognition abilities.

Fusiform Face Area (FFA)

  • Definition and location: Area responsible for face processing discovered through MRI studies by Nancy Kanwisher.

  • Method of assessing brain response:

    • Participants view faces vs. general objects and measurement through percent signal change in FFA.

  • Alternative explanations challenged:

    • Studies involving intact vs. scrambled faces revealed that the FFA responds more to complete faces, supporting the hypothesis of holistic processing.

  • FFA's selectivity tested against other biological stimuli (e.g., hands) revealed stronger responses for faces.

Depth Perception

  • Exploration of how the brain interprets 2D images to perceive depth through various cues:

    • Monocular cues (can work with one eye):

    • Linear perspective: Parallel lines converge in the distance.

    • Shape and texture gradients: Density and clarity decrease with distance.

    • Relative size: Comparing sizes of objects to determine depth based on expected sizes.

    • Interposition: Overlapping objects indicate positional closeness.

    • Shadows: The direction and shape of shadows provide information about 3D space and light sources.

    • Accommodation: The lens of the eye adjusts focus, indicating object distance.

    • Motion parallax: Nearby objects move quickly across the field of vision compared to distant ones.

    • Binocular cues (require both eyes):

    • Retinal disparity: Each eye perceives slightly different images due to their physical separation; greater disparity indicates closer objects.

    • Convergence: The eyes rotate inward when focusing on close objects; the degree of this rotation indicates distance from the viewer.

Course Overview and Fellowship Program Introduction

  • Importance of UX knowledge and experiences discussed, including UX design definitions and principles.

  • Role of UX in enhancing user interactions with products and ensuring good user experiences.

  • Presentation of the UX life cycle: Stages including empathizing, defining, ideation, prototyping, testing, and implementing.

  • Discussion on the significance of personal projects for the fellowship program:

    • Encouragement to develop user experience skills through practical application, including projects like app redesigns.

    • Emphasis on hands-on workshops to enhance skills in tools like Figma.

  • Importance of feedback and collaboration in project development, as well as the possibility to partner with fellow peers for collaborative learning.