Cognitive Psychology: Nature of Perception

• Cognitive psychology explores the nature of perception.

Questions to Consider

• Perceptions can be different even when people respond to the same stimuli .
• Perception relies on knowledge about the environment.

Nature of Perception

• Perception is a conscious experience from stimulating the senses.
• Perception can change when additional information is given.
• Perception includes complex processes, like reasoning.
• It occurs with action.
• Determining what is "out there" requires going beyond the light patterns on the retina.

Why It Is So Difficult to Design a Perceiving Machine

• The stimulus on the receptors is ambiguous due to the inverse projection problem.
• Determining the object that caused a retinal image is challenging.
• It involves extrapolation outward from the retinal image.
• Objects can be hidden or blurred, requiring background knowledge to identify them.
• People can often identify obscured and incomplete objects and objects that are blurry.
• Objects look different depending on the viewpoint.
• The ability to recognize an object is called viewpoint invariance.
• Recognizing an object is difficult for AI because AI is bad at viewpoint invariance.
• Scenes Contain High-Level Information Objects in a scene may provide information about the scene that requires some reasoning.

Information for Human Perception

• Bottom-up processing begins with sensory information received by the receptors.
• Top-down processing involves a person's knowledge or expectations, or anything from your mind.
• Perception is a combination of both top-down and bottom-up processing.
• Bottom-up processing comes from the environment, and top-down processing refers to what the individual brings.

Perceiving Speech and Objects

• A blob may be perceived depending on its context and orientation.

Hearing Words in a Sentence

• Speech Segmentation
• The process of perceiving individual words within the continuous flow of the speech signal.
• Transitional probabilities dictate how likely one speech sound will follow another within a word.
• Statistical learning is a process of learning probabilities and characteristics of language.

Conceptions of Object Perception

• Helmholtz's Theory of Unconscious Inference
• Perceptions result from unconscious assumptions that we make about the environment.
• Likelihood principle makes it easier to determine the most likely pattern of stimuli.
• Gestalt Principles of Organization
• Gestalt psychologists proposed principles that govern perception.
• They also have a perceptual approach to problem-solving involving restructuring.
• This approach reacts partly to structuralism.
• Apparent movement occurs when illusion of movement perception occurs because stimuli in different locations are flashed one after another at the correct timings

Principles of Perceptual Organization

• The principle of good continuation states that points connected form straight or curving lines that belong together.
• Lines are seen as following the smoothest path.
• Overlapped objects are perceived as continuing behind the overlapping one.
• The law of Pragnanz/principle of good figure/principle of simplicity states that stimulus patterns are seen so the resulting structure is as simple as possible.
• The principle of similarity states that things that are similar will be grouped together.
• Taking Regularities in the Environment into Account
• Physical regularities are regularly occurring physical properties of the environment.
• The oblique effect is the perception of vertical and horizontal orientations easier than slanted ones.
• Light-from-above assumption dictates that the light comes from above.
• it is a heuristic that influences how 3D objects are perceived.
• Semantic regularities are characteristics associated with functions carried out in different types of scenes.
• A scene schema is a person's knowledge of what a particular scene likely contains.

Palmer Kitchen Experiment

• Observers used knowledge about kitchens to help perceive a briefly flashed loaf of bread.
• Bayesian inference is the idea that our prediction of an outcome is determined by the initial probability.
• It takes into account the initial probability and the extent to which evidence is consistent with the outcome.

Neurons and Knowledge About the Environment

• Neurons That Respond to Horizontals and Verticals
• The theory of natural selection states characteristics that enhance an animal's ability to survive are passed down.
• The visual system has been shaped by neurons that respond to common environmental features, verticals and horizontals.
• Experience-Dependent Plasticity
• A mechanism causes neurons to develop to best respond to types of stimuli that they experience.
• Kittens raised in only vertical environments developed visual cortices where neurons responded mainly to verticals.
• After training. the fusiform face area (FFA) also reacted to Greebles almost as well as faces.

Perception and Action

• Perception and Action: Behavior
• Movement facilitates perception.
• Movement of an observer relative to an object provides information about the object.
• There is constant coordination between perceiving and acting on an object.

Perception and Action: Physiology

• Brain ablation is removing a specific area from an animal's brain.
• This can assess changes in behavior due to the removal.
• The object discrimination problem is a task involving remembering an object by shape and choosing it among others after a delay.
• This task was hard for monkeys had their temporal lobes removed.
• The landmark discrimination problem is a task involving remembering an object's location and choosing that location after a delay.
• This task was hard for monkeys had their parietal lobes removed.
• The "what" (perception) pathway is a neural pathway extending from the occipital lobe to the temporal lobe.
• It is correlated with perceiving and recognizing objects.
• The "where" (action) pathway is a neural pathway extending from the occipital lobe to the parietal lobe.
• It's correlated with neural processing when people locate objects in space.