Chapter 3: Perception glossary + short answers

Affordance

Affordance

A perceptual property of objects, places, and events that makes clear what actions or behaviors on the part of the perceiver are permitted in interaction with the object, place or event.

Bottom-up process

Cognitive (usually perceptual) process guided by environmental input. Also called "data-driven" process.

Change Blindness

The inability to detect changes to an object or scene, especially when given different views of that object or scene.

Constructivist approach to perception

An understanding of perception as a process requiring the active construction of subjective mental representation not only from perceptual information, but from long-term memory as well.

Context Effects

The effects on a cognitive process (for example, perception) of the information surrounding the target object or event. Sometimes called "expectation effect" because the context is thought to set up certain expectations in the mind of the cognitive processor.

Direct Perception

A theory pf perception, proposed by James J. Gibson, holding that information in the world is "picked up on" by the cognitive processor without much construction of internal representations or inferences. The emphasis is on direct acquisition of information.

Distal stimulus

An object, event, or pattern as it exists in the world. Contrast with proximal stimulus.

Feature

A component, or part, of an object, event, or representation.

form perception

The process by which the brain differentiates objects from their backgrounds.

Gestalt principles of perceptual organization

Laws that explain the regularities in the way people come to the perceptual interpretations of stimuli. The emphasis is on the apprehension of whole structures rather on than the detection and assembly of parts of structures.

Pandemonium model

A model of letter perception based on a bottom-up hierarchy of feature detectors.

pattern recognition

The classification of a stimulus into a category.

percept

The outcome of a perceptual process; the meaningful interpretation of incoming information.

Perception

The interpretation of sensory information to yield a meaningful description or understanding.

Phoneme

The smallest unit of sound that makes a meaningful difference in a given language.

Prosopagnosia

A specific inability to recognize faces, even very familiar ones, with intact recognition of other objects.

Prototype

An abstract representation of an idealized member of a class of objects or events.

Proximal stimulus

Reception of information and its registration by a sense organ -for example, retinal images in the case of vision

Retina

a layer of visual receptor cells at the rear of the eyeball

retinal image

A proximal stimulus for vision, consisting of the projection of light waves reflected from stimuli and projected to a surface at the back of the eye.

Schema

An organized framework for representing knowledge that typically includes characters, plots, and settings, and incorporates both general knowledge about the world and information about particular events.

Size constancy

The phenomenon that ones perception of an object remains constant even as the retinal image of the object changes sizes (i.e. because the object has moved closer or farther away from the perceiver)

Subjective contours

Illusory outline created by certain visual cues that lead to erroneous form perception. The existence of this phenomenon suggests that perception is an active constructive process.

Template

A stored pattern or model to which incoming information is matched in order to be recognized and classified.

Top-down process

Cognitive (usually perceptual) process directed by expectations (derived from context, past learning, or both) to form a larger percept, concept, or interpretation. Also called conceptually driven or theory-driven process.

Visual Agnosia

An impairment in the ability to interpret (but not to see) visual information.

visual search task

A task in which subjects are asked to detect the presence of a particular target against an array of similar stimuli

world superiority effect

The phenomenon that single letters are more quickly identified in the context of words that they are when presented alone or in the context of random letters.

Describe the differences in assumption made by researchers working in (a) the traditional information-processing paradigm, (b) the connectionist paradigm, and (c) the Gibsonian ecological paradigm

The traditional information-processing paradigm, also known as the "computer metaphor" or the "cognitive architecture" approach, assumes that the mind works like a computer, processing information in a series of stages. This approach views the mind as a set of modules or subsystems, each of which performs a specific function, such as perception, memory, or reasoning. Researchers working within this paradigm tend to focus on the internal processes of the mind, such as how information is represented and how it flows through the system. They also often use formal models and mathematical representations to describe these processes. The connectionist paradigm, also known as the "neural network" approach, assumes that the mind works like a network of simple processing units, or "neurons," that are connected to each other. This approach views the mind as a distributed system, in which information is processed by the interactions between many small units, rather than by a series of stages. Researchers working within this paradigm tend to focus on the connections between neurons and the patterns of activity that emerge from these connections. They also often use computer simulations to model these processes. The Gibsonian ecological paradigm, named after psychologist James J. Gibson, assumes that perception is an active process that is directly linked to the structure of the environment, rather than the internal processes of the mind. This approach views the mind as an organism that is constantly engaged in the world, rather than as a passive receiver of information. Researchers working within this paradigm tend to focus on the ways in which the organism and the environment interact, and how this interaction shapes perception. They also often use experiments that involve measuring the behavior of organisms in real-world environments, rather than in artificial laboratory settings.

Describe two of the gestalt laws of perceptual organization, illustrating each with a specific example.

The gestalt laws of perceptual organization are a set of principles that describe how the human brain organizes and interprets visual information. Two of the most well-known laws are: (1) Proximity: Objects that are close to each other are more likely to be perceived as belonging to the same group. For example, in the image of a group of circles, the circles that are close to each other are perceived as belonging to the same group, while the circles that are farther apart are perceived as belonging to separate groups. (2) Similarity: Objects that are similar in some way (e.g. shape, color, size) are more likely to be perceived as belonging to the same group. For example, in the image of a group of circles with different colors, the circles that are the same color are perceived as belonging to the same group, while the circles that are different colors are perceived as belonging to separate groups. There are other laws like continuity, closure, symmetry, and so on. These laws are based on the observation that the brain tends to group together elements in a visual scene in order to make sense of it, and that these grouping tendencies can be described by a set of general principles.

Distinguish between bottom up and top down perceptual processes

Bottom-up and top-down are terms used to describe two different types of perceptual processes. Bottom-up processing refers to the way in which perception is based on the analysis of the physical features of the stimuli. In other words, it is a data-driven process that starts with the basic features of the stimulus, such as color, shape, and texture, and uses these features to build a representation of the object or scene. It is also known as data-driven or bottom-up processing because it is driven by the information that is present in the stimulus itself, rather than by prior knowledge or expectations. Top-down processing refers to the way in which perception is influenced by knowledge, expectations, and context. In other words, it is a concept-driven process that starts with an interpretation of the stimulus based on prior knowledge or expectations and uses this interpretation to guide the analysis of the physical features of the stimulus. It is also known as concept-driven or top-down processing because it is driven by the information that is stored in the mind, rather than by the information that is present in the stimulus itself. Both bottom-up and top-down processes occur simultaneously, but the balance between the two can shift depending on the task and the nature of the stimulus. In some cases, bottom-up processing may be more dominant, while in other cases, top-down processing may be more dominant.

In what ways are featural analysis and prototype matchings models an improvement over template matching models?- In what way are they not?

Featural analysis and prototype matching models are considered improvements over template matching models in terms of their ability to handle variations and variations in input. These models break down the features of an object and compare it to a set of stored features or prototypes, rather than matching the entire object to a stored template. This allows them to recognize an object even when it is presented in different orientations, poses or lighting conditions. Additionally, prototype matching models allow for a degree of similarity or category membership rather than an all-or-nothing match. However, these models are not without their limitations. One limitation is that they can be computationally more complex and require more memory to store the prototypes or features. Additionally, they may have a higher error rate in some cases, as the variations in the input may not match exactly with the stored prototypes.

Describe some real-life examples of context effects in perception?

One of the simplest examples is that of brightness contrast. The apparent brightness of a stimulus depends not only on its own luminance but also on that of the surrounding stimulation. The same gray square looks whiter against a dark background and blacker when placed in a bright surround. Similarly, a white or gray patch will take on an apparent hue that is complementary to the colour of the surround.

Consider Mcclelland and Rumelharts connectionist model of letter perception How might gestalt psychology regard this model, and what would he or she see as the models strengths and weaknesses? How might a cognitive neuropsychologists regard this model. Strengths and weaknesses?

McClelland and Rumelhart's connectionist model of letter perception is a neural network model that simulates the process of recognizing letters by training a network of artificial neurons to respond to different patterns of input that correspond to different letters. This model is based on the assumption that letter recognition is a distributed process that is mediated by the interactions between many small units, rather than by a series of stages. From a gestalt psychology perspective, this model may be seen as a strength in that it acknowledges the role of context and the environment in shaping perception. Gestalt psychology emphasizes that perception is an active process that is directly linked to the structure of the environment and this model acknowledges the same by considering the interactions between the neurons to form a pattern of recognition. However, it may also be seen as a weakness in that it does not account for the holistic and organized nature of perception, which is a key principle in gestalt psychology. From a cognitive neuropsychologist perspective, this model may be seen as a strength in that it is based on a biologically plausible mechanism for letter perception. Also, it may be seen as a weakness in that it does not account for the role of specific brain regions in letter perception, which is a key focus of cognitive neuropsychology. Additionally, this model is a simulation of the cognitive process and may not fully account for the complex nature of the brain and how it handles letter recognition.

Discuss the following: "Part of the reason that J. J. Gibson's supporters and detractors have such spirited debates is that they are talking past each other. Gibson doesn't just present a different model of perception he redefines what the task of perception is."

J. J. Gibson's ecological approach to perception is distinct from traditional information-processing models of perception, which focus on the internal processes of the mind, such as how information is represented and how it flows through the system. Gibson, on the other hand, defines perception as an active process that is directly linked to the structure of the environment, which he refers to as "affordances." This means that perception is not just about processing information, but also about how the organism interacts with the environment in order to achieve a goal. This redefinition of perception has led to spirited debates between Gibson's supporters and detractors, as they have fundamentally different views on what the task of perception is. Gibson's supporters argue that his approach provides a more accurate and complete understanding of perception, as it acknowledges the importance of the environment and the organism's interactions with it. On the other hand, Gibson's detractors argue that his approach is too narrow, as it does not account for the internal processes of the mind, such as attention and memory, that also play a critical role in perception. In summary, part of the reason that J. J. Gibson's supporters and detractors have such spirited debates is that they are talking past each other, as Gibson's ecological approach to perception redefines the task of perception in a fundamentally different way from traditional information-processing models. This leads to different perspectives and disagreements on the importance and limitations of Gibson's approach.

What do the different agnosias tell us about perception? (Hard: What are the limitations, both theoretical and empirical, of using case studies of braindamaged individuals to inform theories of "normal" cognitive functions?)

Agnosias are a group of neurological disorders that affect the ability to recognize objects, faces, or other stimuli, despite normal sensory function. Different types of agnosias provide insight into the different stages and processes involved in perception. For example, prosopagnosia, which is the inability to recognize faces, suggests that there are specialized mechanisms for recognizing faces and that these mechanisms are separate from those used to recognize other objects. Similarly, object agnosia, which is the inability to recognize objects, suggests that there are specialized mechanisms for recognizing different categories of objects, such as animals or tools, and that these mechanisms are distinct from those used to recognize faces or other stimuli. Agnosias also provide insight into the relationship between perception and other cognitive functions, such as memory and attention. For example, some types of agnosias are associated with difficulties in attention or memory, which suggests that these functions are closely linked to perception. Using case studies of brain-damaged individuals to inform theories of "normal" cognitive functions is a common approach in cognitive neuroscience, but it also has limitations. One limitation is that it is difficult to determine whether the deficits observed in brain-damaged individuals are caused by the injury itself or by pre-existing differences in brain structure or function. Additionally, case studies are subject to a selection bias, as the individuals studied may not be representative of the general population. Furthermore, the patterns of deficits in brain-damaged individuals may not match the patterns of normal variation in the population. Therefore, the results from case studies of brain-damaged individuals should be used with caution and need to be further supported by other methods such as behavioral experiments and neuroimaging studies to better inform theories of normal cognitive functions.