Unit 1 Test Overview

Test Data

• Grades will be recorded in the grade book by tomorrow.

• Period 1 & 3 graded; Period 2 & 4 scored.

• Period 1 Stats:

  • Test Average: 78%

  • Mode: 77%

  • Standard Deviation: 0.09415

• Period 3 Stats:

  • Test Average: 80%

  • Mode: 89%

  • Standard Deviation: 0.09482

General Announcements

• Write in complete sentences for all responses.

• Test corrections will begin once all students have made up their test.

Introduction to Sensation

Basic Concepts of Sensation

• Sensation allows us to obtain crucial information from our environment.

  • Human ears are most sensitive to sound frequencies associated with voices.

  • Frogs have specialized cells in their eyes sensitive to dark, moving objects.

  • Male silkworm moths can detect pheromones from females using odor receptors.

Processing Sensations and Perceptions

Distinction Between Sensation and Perception

• Sensation:

  • Process where sensory receptors and nervous system receive and represent stimulus energies.

• Perception:

  • Process where the brain organizes and interprets sensory information.

Continuous Process

• Sensation and perception work together as a continuous unit.

  • Bottom-up Processing: Information processing from the sensory receptors to the brain's higher-level processing.

  • Top-down Processing: Guided by higher-level mental processes that influence perception.

• Transduction:

  • Sensory systems convert external energies into neural impulses usable by the brain.

  • All senses perform the following:

    • Receive sensory stimulation.

    • Transform stimulation into neural impulses.

    • Deliver neural information to the brain.

Thresholds

Absolute Threshold

• Studied by Gustav Fechner; defines the edge of awareness for faint stimuli.

  • Signal Detection Theory:

    • Predicts signal detection; assumes no single absolute threshold; detection influenced by psychological state.

• Subliminal Stimuli:

  • Stimuli that cannot be consciously detected 50% of the time.

• Difference Threshold:

  • Minimum stimulus difference detectable half the time; influenced by Weber's Law.

  • Weber's Law:

    • For average persons to perceive a difference, stimuli must differ by a constant minimum percentage rather than a constant amount.

Sensory Adaptation

• Continuous exposure to a stimulus causes nerve cells to fire less frequently; reduced awareness occurs.

• Sensory adaptation enables focusing on informative changes in the environment.

• Key Concept: We perceive the world not exactly as it is, but as useful for us.