Perception midterm 1

Absolute threshold

The smallest stimulus level that can just be detected

Action

Motor activities in response to a stimulus.

Bottom-up processing

Processing that is based on the information on the receptors. Also called data-based processing. It involves perception starting with the stimulus itself and building up to the final perception.

Categorize

Placing objects into categories, such as “tree,” “bird,” “car.” This process helps in organizing and interpreting sensory information.

Cerebral cortex

The 2-mm-thick layer that covers the surface of the brain and contains the machinery for creating perception, as well as for other functions, such as language, memory, and thinking. It is divided into four lobes: frontal, parietal, temporal, and occipital, each associated with different sensory and cognitive functions.

Classical psychophysical methods

The methods of limits, adjustment, and constant stimuli, described by Fechner, that are used for measuring thresholds. These methods help determine the smallest detectable difference between stimuli or the minimum intensity required for a stimulus to be perceived.

Difference threshold

The minimum difference that must exist between two stimuli before we can tell the difference between them

Distal stimulus

The stimulus “out there,” in the external environment. It refers to the actual object or event that exists in the world, as opposed to the perception of it.

Electromagnetic spectrum

Continuum of electromagnetic energy that extends from very-short-wavelength gamma rays to long-wavelength radio waves. Visible light is a narrow band within this spectrum.

Frontal lobe

Receiving signals from all of the senses, the frontal lobe plays an important role in perceptions that involve the coordination of information received through two or more senses. It also serves functions such as language, thought, memory, and motor functioning

Grating acuity

The narrowest spacing of a grooved surface on the skin for which orientation can be accurately judged. See also Two-point thresholdI. t is a measure of the spatial resolution of touch perception, reflecting the ability to discern fine details in textures.

Knowledge

Any information that the perceiver brings to a situation. See also Top-down processing. It influences perception by shaping how stimuli are interpreted based on prior experiences and expectations.

Magnitude estimation

A psychophysical method in which the subject assigns numbers to a stimulus that are proportional to the subjective magnitude of the stimulus. This technique allows researchers to quantify perceptions of intensity or magnitude based on participants' responses.

Neural processing

Operations that transform electrical signals within a network of neurons or that transform the response of individual neurons. This processing is essential for interpreting sensory information and facilitating perception.

Oblique effect

Enhanced sensitivity to vertically and horizontally oriented visual stimuli compared to obliquely oriented (slanted) stimuli. This effect has been demonstrated by measuring both perception and neural responding in visual processing tasks, highlighting the importance of orientation in visual perception.

Occipital lobe

The region of the brain located at the back of the head, primarily responsible for processing visual information. It plays a crucial role in interpreting visual stimuli and integrating visual perception with other sensory inputs.

Parietal lobe

A lobe at the top of the cortex that is the site of the cortical receiving area for touch and is the termination point of the dorsal (where or how) stream for visual processing. It is involved in spatial awareness, attention, and integrating sensory information from different modalities.

Perceived magnitude

A perceptual measure of stimuli, such as light or sound, that indicates the magnitude of experience.It reflects how intense or strong a stimulus is perceived to be by an observer, often influenced by prior exposure and contextual factors.

Perception

The process by which sensory information is organized, interpreted, and consciously experienced. It involves transforming stimuli from the environment into meaningful experiences.

Perceptual process

A sequence of steps leading from the environment to perception of a stimulus, recognition of the stimulus, and action with regard to the stimulus.It encompasses attention, sensation, and interpretation, ultimately resulting in an individual's understanding of their surroundings.

Phenomenological report

Method of determining the relationship between stimuli and perception in which the observer describes what he or she perceives. It emphasizes subjective experiences and the qualities of perception from the observer's perspective.

Physiology–behavior relationship

The connection between physiological processes and behavioral responses, highlighting how bodily functions influence actions and perceptions.

Primary receiving area

Area of the cerebral cortex that first receives most of the signals initiated by a sense’s receptors. For example, the occipital cortex is the site of the primary receiving area for vision, and the temporal lobe is the site of the primary receiving area for hearing.It is crucial for processing sensory information before it is relayed to other areas for further interpretation.

Proximal stimulus

The stimulus that is directly received by the sensory receptors, representing the immediate sensory input that results from an object in the environment. In vision, this would be the image on the retina.

Psychophysics

Traditionally, the term psychophysics refers to quantitative methods for measuring the relationship between properties of the stimulus and the subject’s experience. In this book, all methods that are used to determine the relationship between stimuli and perception will be broadly referred to as psychophysical methods. Psychophysics involves studying how physical stimuli correlate with sensory perception.

Rat–man demonstration

The demonstration in which presentation of a “ratlike” or “manlike” picture influences an observer’s perception of a second picture, which can be interpreted either as a rat or as a man. This demonstration illustrates an effect of top-down processing on perception. It shows how prior knowledge and expectations can shape the interpretation of sensory information.

Reaction time

The time between presentation of a stimulus and an observer’s or listener’s response to the stimulus. Reaction time is often used in experiments as a measure of speed of processing. It can be influenced by various factors, including attention, complexity of the task, and individual differences.

Recognition

The ability to place an object in a category that gives it meaning—for example, recognizing a particular red object as a tomato. This process involves identifying previously encountered stimuli, allowing individuals to retrieve information about them from memory.

Sensation

Often identified with elementary processes that occur at the beginning of a sensory system. See also Structuralism. Sensation refers to the initial detection of stimuli by sensory receptors, which then leads to the perception of those stimuli. It involves the processing of basic sensory information, such as light, sound, and touch.

Sensory receptors

Cells specialized to respond to environmental energy, with each sensory system’s receptors specialized to respond to a specific type of energy. These receptors convert physical stimuli into neural signals, enabling the brain to interpret sensory information.

Stimulus–behavior relationship

The connection between a specific external stimulus and the resulting behavior or response it elicits in an organism. This relationship is fundamental in understanding how stimuli affect actions and reactions. behavioral responses can be perception, recognition, or action.

Temporal lobe

A lobe on the side of the cortex that is the site of the cortical receiving area for hearing and the termination point for the ventral, or what, stream for visual processing. A number of areas in the temporal lobe, such as the fusiform face area and the extrastriate body area, serve functions related to perceiving and recognizing objects.It plays a crucial role in processing auditory information and is involved in memory and emotion.

Top-down processing (knowledge-based processing)

Processing that starts with the analysis of high-level information, such as the knowledge a person brings to a situation. Also called knowledge-based processing. Distinguished from bottom-up, or data-based processing, which is based on incoming data. This type of processing involves expectations and prior experiences influencing perception, allowing for quicker recognition of familiar stimuli.

Transduction

In the senses, the transformation of environmental energy into electrical energy. For example, the retinal receptors transduce light energy into electrical energy

Visual object agnosia

The inability to recognize objects.

Action potential

Rapid increase in positive charge in a nerve fiber that travels down the fiber. Also called the nerve impulse and is essential for neural communication. It occurs when a neuron reaches a certain threshold of depolarization, allowing ions to flow in and out, creating an electrical signal.

Axon

The part of the neuron that conducts nerve impulses over distances. Also called the nerve fiber. It transmits electrical signals away from the cell body to other neurons or muscles.

Brain imaging

Procedures that make it possible to visualize areas of the human brain that are activated by different types of stimuli, tasks, or behaviors. The most common technique used in perception research is functional magnetic resonance imaging (f MRI).

Broca’s area

A region in the frontal lobe of the brain associated with speech production and language processing. Damage to this area can result in Broca's aphasia, characterized by difficulty in forming grammatically correct sentences.

Cell body

The part of a neuron that contains the neuron’s metabolic machinery and that receives stimulation from other neurons. It is also known as the soma and plays a crucial role in maintaining the cell's health and function.

Dendrites

Nerve processes on the cell body that receive stimulation from other neurons. They play a key role in transmitting signals to the cell body and are essential for communication between neurons.

Depolarization

When the inside of a neuron becomes more positive, as occurs during the initial phases of the action potential. Depolarization is often associated with the action of excitatory neurotransmitters. This process involves the influx of sodium ions into the neuron, leading to a change in electrical charge.

Distributed representation

Occurs when a stimulus causes neural activity in a number of different areas of the brain, so the activity is distributed across the brain. This means that information is processed in parallel rather than in a single location, allowing for more complex representations of stimuli.

Excitatory response

The response of a nerve fiber in which the firing rate increases. This occurs when excitatory neurotransmitters bind to receptors, leading to depolarization and an increased likelihood of action potentials.

Falling phase of the action potential

In the axon, or nerve fiber, the increase in negativity from 140 mV back to 270 mV (the resting potential level) that occurs during the action potential. This increase in negativity is associated with the flow of positively charged potassium ions (K1) out of the axon. This phase follows depolarization and involves repolarization as potassium ions exit the neuron, restoring the resting membrane potential.

Functional connectivity

Neural connectivity between two areas of the brain that are activated when carrying out a specific function. This connectivity reflects the temporal correlation of neural activity and is important for understanding how different brain regions work together during cognitive tasks.

Functional magnetic resonance imaging (fMRI)

A brain imaging technique that indicates brain activity in awake, behaving organisms. The fMRI response occurs when the response to a magnetic field changes in response to changes in blood flow in the brain.This technique measures changes in blood oxygenation level dependent (BOLD) signals, allowing researchers to infer neural activity based on increased blood flow to active brain regions.

Grandmother cell

A highly specific type of neuron that fires in response to a specific stimulus, such as a person’s grandmother. This concept suggests that certain neurons are responsible for recognizing highly specific concepts or objects, potentially playing a role in memory and recognition.

Hyperpolarization

When the inside of a neuron becomes more negative. Hyperpolarization is often associated with the action of inhibitory neurotransmitters. This process makes it less likely for the neuron to fire an action potential, thus reducing the likelihood of transmitting a signal.

Inhibitory response

Occurs when a neuron’s firing rate decreases due to inhibition from another neuron or the action of inhibitory neurotransmitters, leading to a reduced likelihood of action potential generation.

Ions

Charged particles that play a crucial role in neuronal signaling and the generation of action potentials, including sodium NA+, potassium K+, calcium, and chloride CL- ions the main ions found within nerve fibers and in the liquid that surrounds nerve fibers.

Magnetic resonance imaging (MRI)

Brain scanning technique that makes it possible to create images of structures within the brain. MRI uses strong magnetic fields and radio waves to generate detailed images, aiding in the diagnosis of neurological conditions.

Mind–body problem

One of the most famous problems in science: How do physical processes such as nerve impulses or sodium and potassium molecules flowing across membranes (the body part of the problem) become transformed into the richness of perceptual experience (the mind part of the problem)?This philosophical question explores the relationship between consciousness and the physical brain, questioning how mental states arise from physical processes.

Modularity

The idea that specific areas of the cortex are specialized to respond to specific types of stimuli. This concept suggests that different cognitive functions are processed in distinct modules within the brain, allowing for efficient and specialized processing of information.

Module

A structure that processes information about a specific behavior or perceptual quality. Often identified as a structure that contains a large proportion of neurons that respond selectively to a particular quality, such as the fusiform face area, which contains many neurons that respond selectively to faces. Modules are thought to operate independently, allowing for specialized processing without interference from other cognitive functions.

Nerve fiber

In most sensory neurons, the long part of the neuron that transmits electrical impulses from one point to another. Also called the axon. It conducts signals away from the neuron's cell body to communicate with other neurons or muscles.

Neurons

The structure that transmits electrical signals in the body. Key components of neurons are the cell body, dendrites, and the axon or nerve fiber. Neurons are specialized cells that transmit electrical impulses throughout the nervous system, facilitating communication between the brain and the rest of the body.

Neuropsychology

The study of the behavioral effects of brain damage in humans.

Neurotransmitters

A chemical stored in synaptic vesicles that is released in response to a nerve impulse and has an excitatory or inhibitory effect on another neuron.

Permeability

A property of a membrane that refers to the ability of molecules to pass through it. If the permeability to a molecule is high, the molecule can easily pass through the membrane. This property is crucial in regulating the movement of ions and other substances in and out of cells, influencing cellular function and signaling.

Phrenology

Belief that different mental faculties could be mapped onto different brain areas based on the bumps and contours on a person’s skull.It was an early theory in psychology that suggested personality traits and intellectual abilities were determined by the shape of the skull.

Population coding

Representation of a particular object or quality by the pattern of firing of a large number of neurons. It suggests that individual neurons contribute to the perception of sensory information through their collective activity.

Propagated response

A response, such as a nerve impulse, that travels all the way down the nerve fiber without decreasing in amplitude.

Receptor sites

Small area on the postsynaptic neuron that is sensitive to specific neurotransmitters. They play a crucial role in synaptic transmission, allowing communication between neurons.

Refractory period

The time period of about 1/1,000th of a second that a nerve fiber needs to recover from conducting a nerve impulse. No new nerve impulses can be generated in the fiber until the refractory period is over and the neuron returns to its resting state. During this time, the neuron is less responsive to stimuli.

Resting potential

The difference in charge between the inside and the outside of the nerve fiber when the fiber is not conducting electrical signals. Most nerve fibers have resting potentials of about 270 mV, which means the inside of the fiber is negative relative to the outside.This potential is crucial for the generation of action potentials, as it sets the stage for the neuron's responsiveness to stimuli.

Resting-state fMRI

The signal recorded using functional magnetic resonance imaging when the brain is not involved in a specific task. It reflects baseline brain activity and connectivity patterns, providing insights into the brain's functional organization.

Resting-state functional connectivity

A method in which resting-state fMRI is used to determine functional connectivity.

Rising phase of the action potential

In the axon, or nerve fiber, the decrease in negativity from 270 mV to 140 mV (the peak action potential level) that occurs during the action potential. This increase is caused by an inflow of Na+ ions into the axon. (2)

Seed location

Location on the brain that is involved in carrying out a specific task and which is used a reference point when measuring resting-state functional connectivity.It serves as a reference for assessing correlations in brain activity with other regions during rest.

Sensory coding

How neurons represent various characteristics of the environment. See also Population coding; Sparse coding; Specificity codingIt refers to the process by which sensory information is transformed into neural signals that the brain can interpret. This includes the mechanisms by which different sensory modalities encode stimuli.

Sparse coding

The idea that a particular object is represented by the firing of a relatively small number of neurons compared to the total number of neurons in the network. This allows for efficient representation and processing of information.

Specificity coding

Type of neural code in which different perceptions are signaled by activity in specific neurons. See also Distributed representation This suggests that individual neurons are selectively responsive to particular stimuli or features, allowing for precise encoding of information related to specific objects or events.

Spontaneous activity

Nerve firing that occurs in the absence of environmental stimulation. This activity is intrinsic to the neural circuitry and can influence sensory perception and processing.

Structural connectivity

The structural “road map” of fibers connecting different areas of the brain.

Synapse

A small space between the end of one neuron (the presynaptic neuron) and the cell body of another neuron (the postsynaptic neuron).

Task-related fMRI

fMRI measured as a person is engaged in a specific task.

Wernicke’s area

An area in the temporal lobe involved in speech perception. Damage to this area causes Wernicke’s aphasia, which is characterized by difficulty in understanding speech.

Absorption spectrum

A plot of the amount of light absorbed by a visual pigment versus the wavelength of light.It shows how different wavelengths are absorbed, indicating the pigment's sensitivity to light.

Accommodation

In vision, bringing objects located at different distances into focus by changing the shape of the lens. This process allows the eye to adjust for near and far vision.

Amacrine cells

A neuron that transmits signals laterally in the retina. Amacrine cells synapse with bipolar cells and ganglion cells.They play a role in processing visual information and enhancing contrast.

Axial myopia

Myopia (nearsightedness) in which the eyeball is too long. See also Refractive myopia. This leads to difficulty seeing distant objects clearly, as light rays focus in front of the retina.

Bipolar cells

A retinal neuron that receives inputs from the visual receptors and sends signals to the retinal ganglion cells. (3)They play a crucial role in transmitting visual information from photoreceptors to ganglion cells, contributing to the processing of visual signals.

Blind spot

The small area where the optic nerve leaves the back of the eye. There are no visual receptors in this area, so small images falling directly on the blind spot cannot be seen.This area is also known as the optic disc, and it results in a gap in the visual field where no image detection occurs.

Center-surround antagonism

The competition between the center and surround regions of a center-surround receptive field, caused by the fact that one is excitatory and the other is inhibitory. Stimulating center and surround areas simultaneously decreases responding of the neuron, compared to stimulating the excitatory area alone. This mechanism enhances contrast and helps in detecting edges in visual stimuli.

Center-surround receptive field

A receptive field that has a center-surround organization. The center is typically excitatory while the surround is inhibitory, allowing for enhanced contrast detection in visual processing.

Chevreul illusion

Occurs when areas of different lightness are positioned adjacent to one another to create a border. The illusion is the perception of a light band on the light side of the border and a dark band on the dark side of the border, even though these bands do not exist in the intensity distribution. This illusion demonstrates the effects of simultaneous contrast, where the perceived brightness of an area is influenced by the brightness of adjacent areas.

Cone spectral sensitivity

A plot of visual sensitivity versus wavelength for cone vision. Often measured by presenting a small spot of light to the fovea, which contains only cones. Can also be measured when the eye is light adapted, so cones are the most sensitive receptors. It illustrates how different types of cones respond to various wavelengths of light, indicating their role in color vision.

Cones

Cone-shaped receptors in the retina that are primarily responsible for vision in high levels of illumination and for color vision and detail vision. They are concentrated in the fovea and function best in bright light, distinguishing colors through three types of cones sensitive to different wavelengths.

Cornea

The transparent focusing element of the eye that is the first structure through which light passes as it enters the eye. The cornea is the eye’s major focusing element. It provides most of the eye's optical power and plays a crucial role in refracting light to help form clear images on the retina.

Dark adaptation

Visual adaptation that occurs in the dark, during which the sensitivity to light increases. This increase in sensitivity is associated with regeneration of the rod and cone visual pigments. It allows the eyes to adjust from bright to low light conditions, enhancing the ability to see in dim environments.

Dark adaptation curve

The function that traces the time course of the increase in visual sensitivity that occurs during dark adaptation.It shows the relationship between time spent in darkness and the sensitivity of the eye to light, illustrating how quickly the eyes adjust to low light conditions.

Detached retina

A condition in which the retina is detached from the back of the eye. This can lead to vision loss and requires immediate medical attention. Symptoms may include flashes of light, floaters, or a shadow over the visual field.

Edge enhancement

An increase in perceived contrast at borders between regions of the visual field. This phenomenon occurs due to the way the visual system processes edges, making them appear sharper and more defined, thus improving object recognition and depth perception.

Excitatory area

Area of a receptive field that is associated with excitation. Stimulation of this area causes an increase in the rate of nerve firing. The excitatory area of a receptive field is the region where stimulus presence leads to an increase in the firing rate of sensory neurons, enhancing the perception of the stimulus.

Excitatory-center, inhibitory-surround receptive field

A center-surround receptive field in which stimulation of the center area causes an excitatory response and stimulation of the surround causes an inhibitory response. This type of receptive field is crucial for processing visual information, as it enhances contrast and edge detection, allowing for improved perception of stimuli in the environment.

Fovea

A small area in the human retina that contains only cone receptors. The fovea is located on the line of sight, so that when a person looks at an object, the center of its image falls on the fovea.

Ganglion cells

A neuron in the retina that receives inputs from bipolar and amacrine cells. The axons of the ganglion cells are the nerve fibers that travel out of the eye in the optic nerve. They play a crucial role in transmitting visual information from the retina to the brain.

Horizontal cells

A neuron that transmits signals laterally across the retina. Horizontal cells synapse with receptors and bipolar cells to help integrate and regulate input from multiple photoreceptors, enhancing contrast and spatial resolution in visual processing.

Hyperopia

A condition causing poor vision in which people can see objects that are far away but do not see near objects clearly. Also called farsightedness. It occurs when the eyeball is too short or the cornea is too flat, resulting in light being focused behind the retina.