I85PREP
⌘ K
Maharashtra HSC Psychology study materials
Maharashtra HSC Psychology study resources

Maharashtra HSC Psychology: Sensation, Attention and Perception

Maharashtra HSC Psychology · Work through your exam, one topic at a time.

All guide sections

Sensation, Attention and Perception

Sensation is detection by sense organs; perception is interpretation and organisation of that sensory input. The exam tests thresholds, types of attention, Gestalt grouping laws, constancies, depth cues and the explanation of visual illusions.

Thresholds and adaptation

  • Absolute threshold: weakest stimulus detected 50% of the time.
  • Difference threshold (JND): smallest detectable change, 50% of the time; Weber's law states the JND is a constant fraction of the original stimulus.
  • Sensory adaptation: responsiveness declines under constant stimulation (you stop feeling your wristwatch).
  • Subliminal stimuli fall below the absolute threshold; their effects are weak and short-lived.

Attention

  • Selective (filtering; cocktail-party effect), divided (limited capacity, degrades with task difficulty), sustained (vigilance over time).
  • External determinants: intensity, size, movement, contrast, novelty. Internal: interest, need, mental set, mood.

Perception

  • Bottom-up (data-driven) versus top-down (concept-driven) processing.
  • Gestalt laws: figure–ground, proximity, similarity, continuity, closure, common fate.
  • Constancy: size, shape, brightness, colour.
  • Depth cues - binocular: retinal disparity, convergence; monocular: linear perspective, interposition, relative size, texture gradient, motion parallax, height in the plane.
  • Perceptual set: expectation biases interpretation.

Worked example

In the Müller-Lyer figure, one line looks longer although both are equal. The version resembling a receding corner is interpreted as farther away; size constancy scales the “distant” line upward, so it appears longer. The distortion arises in interpretation, not in the retina, which is why it persists even when you know the answer.

Traps

  • Sensation is not perception; detection differs from interpretation.
  • Absolute threshold and JND are different concepts.
  • Divided attention is limited, not unlimited.
  • Extrasensory perception lacks scientific support and is not treated as a valid perceptual process.