Cognitive Psych Chapt 3

Some Questions We Will Consider

  • Why can two people experience different perceptions in response to the same stimulus? (68)

  • How does perception depend on a person's knowledge about environmental characteristics? (74)

  • How does the brain become tuned to respond best to things likely to appear in the environment? (79)

  • What is the connection between perception and action? (80)

Crystal's Experience on the Beach

  • Crystal starts her run on the beach at sunrise, observing a distant object in the mist.

    • Initial perception: A piece of driftwood, which transforms in her mind as she approaches.

    • Realization: The object is an old beach umbrella she saw the day before.

  • Perception Characteristics Illustrated by Crystal's Experience:

    • Change based on added information: Crystal's perception shifted as she got closer to the umbrella.

    • Involves reasoning: She recalled seeing the umbrella previously, influencing her understanding of the object.

    • Perception is a process: The correction of her error required a cognitive process similar to problem-solving.

  • The episode also shows how perception is intertwined with action as she interacts with her environment (e.g., checking coiled rope, picking up her coffee).

The Nature of Perception

  • Definition: Perception consists of experiences resulting from stimulation of the senses.

  • Key Implications:

    • Perceptions can change actively based on new information, indicating cognitive processing.

    • Perception is usually automatic but involves invisible, complex processes resembling reasoning.

    • Perception allows for coordinating actions in real-time interactions.

The Connection Between Perception and Action

  • Everyday Examples:

    • Recognizing and grasping objects requires constant feedback loops between perception and action.

    • Activities like picking up a cup involve recognizing its location and properties, integrating sensory input with movement planning.

Human versus Computer Perception

  • Comparing Roger’s experience of perceiving objects in the city from PNC Park to computer vision systems:

    • Humans perceive objects (like buildings) naturally, while computers face significant challenges in object recognition.

  • Perceptual Puzzles:

    • Examples presented illustrate how ambiguity in stimuli complicates object recognition.

    • Proving that the perceptual system overcomes these puzzles through experience and deduction—a task still difficult for computers.

Challenges in Designing a Perceiving Machine

  • Receptive Ambiguity: Retinal images can stem from numerous possible objects, complicating recognition (inverse projection problem).

  • Hidden or Blurred Objects: Humans can identify partially covered or unclear shapes effectively.

  • Viewpoint Variance: Objects appear differently when viewed from varying angles; human recognition adapts seamlessly, while computer vision struggles.

  • Complex Scenes: Real-world scenes contain high-level information contributor to perception difficulty for computers.

Mechanisms of Perception

  • Bottom-Up Processing: Initiated when environmental stimuli activate receptors, leading to signal transmission to the brain.

  • Top-Down Processing: Involves cognitive factors like prior knowledge and expectations about the environment, influencing perception profoundly.

    • Example: Prior experience helps identify rapidly flashed objects more accurately in relevant contexts.

Examples of Top-Down Processing:

  • Multiple Personalities of a Blob: Different interpretations based on orientation and context illustrate perceptual flexibility.

  • Speech Perception: Identifying words accurately amidst continuous speech demonstrates reliance on top-down processing to discern meaning.

Conceptions of Object Perception

  • Helmholtz's Theory: Unconscious Inference:

    • Likelihood principle explains how the brain interprets ambiguous stimuli based on prior experiences unconsciously.

  • Gestalt Principles:

    • Perception should not be considered merely sensation aggregation but also about organization principles that inform how we see stimuli contextually (e.g. good continuation, pragnanz, similarity).

  • Regularities of the Environment:

    • Humans naturally associate frequently occurring patterns in the environment (physical and semantic regularities) that simplify perception.

Bayesian Inference:

  • Mathematical framework that assesses prior probabilities against available evidence to improve perception reliability, applicable to object identification and decision-making scenarios.

Two Streams of Processing: Action and Perception

  • What Pathway: Ventral, linking object identity to the temporal lobe

  • Where Pathway: Dorsal, linking object location to the parietal lobe

  • The mentioned pathways elucidate coordination between perception and action, allowing insightful interactions with the world around us.

Mirror Neurons and Understanding Actions

  • Discovery of Mirror Neurons: These neurons activate both during action performance and observation, suggesting they may play a role in understanding intentions behind actions.

  • Relating Mirror Neuronal Activity to Intent: Activation patterns shift based on context, highlighting their importance in interpreting others' actions motives and enhancing social interactions.

Summary of Key Points

  1. Perception is a systematic process influenced by a blend of sensory input and cognitive factors.

  2. Variability in perception among individuals can provide insight into environmental stimuli processing.

  3. Understanding perception through real-world versus computational paradigms emphasizes human adaptability.

  4. Perception goes beyond visual recognition to include understanding through experience and inference.

  5. Physiological evidence supports the existence of meaningful neural pathways linking perception and action.

  6. Understanding actions and intentions appears vital for social interactions, informed by advanced neuroscience concepts.