Psycho Group Ass
Psycho Group Ass
Psycho Group Ass
Page
Definition of sensation and perception .. ...2
Selectivity of perception....,...........,.................................,............6
From perception...…................….......................….........................7
Depth perception.......…..................,............................................9
Perceptual illusion.....................................................................9
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Introduction
Sensation and perception are two interrelated processes that allow us to experience and make
sense of the world around us. From the way we see colors and shapes to the way we taste and
smell food, these processes are the building blocks of our daily experiences. Understanding
how sensation and perception work together is crucial to understanding not only how we
experience the world but also how we build our understanding and beliefs about it. In this
passage, we will explore the intricacies of these processes, their relationship with each other,
and the role they play in shaping our perception of reality.
What is sensation?
Light—vision Sound—hearing
Chemicals—taste and smell Pressure, temperature, pain—sense of touch
Orientation, balance—kinesthetic senses
A physical stimulus must first be introduced. For example: Our senses respond to a limited range of
environmental stimuli. For example, we cannot hear sound of frequencies above 20,000 Hz, even
though dogs can hear them.
Properties of light
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iii. Complexity or purity (experienced as saturation)
iv. As noted above, there is not a one-to-one relationship between physical properties and
perceptual experience. For example, intensity can also influence perception of pitch.
Transduction is the process of converting energy of a stimulus into neural activity. The stimulus
is recoded as a neural pattern.
. Transduction can be affected by our experiences, such as through adaptation; a constant level
of stimulus results in a decreased response over time. With continued exposure, the neural
response to the stimulus may change. Adaption is also perceptual, not just sensory.
What is perception?
Perception is the process that organizes sensations into meaningful patterns. It is the process
whereby the brain interprets sensations, giving them order and meaning. 3
Perception is the process of selecting and identifying information from the environment.
A. Perception is the interpretation of information from the environment so that we can identify
its meaning.
B. Sensation usually involves sensing the existence of a stimulus, whereas perceptual systems
involve the determination of what a stimulus is.
C. Expectations and perception: Our knowledge about the world allows us to make fairly
accurate predictions about what should be there—so we don’t need a lot of information from
the stimulus itself.
1. Bottom-up processes are processes that are involved in identifying a stimulus by analyzing
the information available in the external stimulus.
This also refers to information processing that begins at the receptor level and continues to
higher brain centers. 3
2 Top-down processes are processes that are involved in identifying a stimulus by using the
knowledge we already possess about the situation. This knowledge is based on past experiences and
allows us to form expectations about what we ought to perceive.
a. This also refers to information processing that begins in higher brain centers and proceeds to
receptors.
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b. Top-down processes allow for perceptual judgments and bias to start influencing how we
process incoming stimuli and information. Early incoming information is already being processed in
terms of top-down influences and previous experience. 4
Sensory laws
Sensory threshold
Sensory threshold is the level of intensity or concentration at which a person is able to perceive a
particular sensory stimulus, such as sound, light, taste, or odor. It is the minimum amount of stimulation
required for a person to detect a sensation. The sensitivity of an individual's sensory thresholds can vary
depending on a variety of factors, such as age, health, and experience. Some people may have a lower
sensory threshold, which means they are more sensitive to stimuli, while others may have a higher
sensory threshold, which means they are less sensitive to stimuli and may require more intense
stimulation to perceive a sensation.
There are two laws of sensory threshold: The law of absolute threshold and the law of difference
threshold. 4
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The law of Absolute thershold
The law of Absolute threshold is the minimum amount of stimulation required for a person to detect a
sensory stimulus at least 50% of the time. It is the lowest level of stimulation that can be detected by a
specific sensory system. This law applies to all sensory modalities, including vision, hearing, touch, taste,
and smell. The absolute threshold can vary depending on factors such as the age, health, and sensory
acuity of the individual, as well as the conditions under which the stimulus is presented.
The best example for the law of absolute threshold is hearing. The minimum amount of sound energy
required to detect a sound is known as the absolute threshold of hearing. It is the minimum volume or
intensity of sound that can be heard by a person. For example, if we are sitting in a completely quiet
room and a sound is made at a certain decibel level, our ears will pick it up and send a signal to our brain
to process the sound. However, if the decibel level is too low, we won't be able to hear the sound, and
the sound will be below the absolute threshold of hearing. which states that there is a limit below which
we cannot detect a stimulus.
The law difference threshold, also known as the just noticeable difference (JND), is the smallest
difference between two stimuli that can be detected by a person. It is the point at which a sensory
change is perceived as different from the original stimulus. The law difference threshold varies
depending on the type of stimulus and the individual's sensitivity to it.
Suppose you are sitting in a quiet room and you can hear a pin drop. Suddenly, someone turns on a loud
radio. At first, the sound seems overwhelming, but as time passes, you adjust to the new level of noise
and eventually, the radio becomes less noticeable. This adjustment is caused by the law of difference
threshold.
This law is important in understanding how humans perceive and react to changes in their environment,
including changes in temperature or sensory input. It highlights the importance of measuring and
controlling stimuli in order to achieve from individuals.
Weber's Law of Difference Threshold states that the smallest noticeable difference (or "just noticeable
difference") between two stimuli is proportional to the magnitude of the stimuli themselves. In other
words, if two stimuli are very different (e.g. one is very bright and one is very dim), the difference
between them needs to be relatively large in order to be noticed. On the other hand, if two stimuli are
very similar (e.g. two shades of gray that are almost identical), the difference between them can be
much smaller and still be noticeable.
Weber's law can be expressed mathematically as ΔI/I = k, where ΔI is the smallest detectable difference
in the intensity of a stimuli, I is the initial intensity of the stimuli, and k is a constant known as the Weber
fraction. The Weber fraction varies depending on the nature of the stimuli and the sense being used to
detect it.
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Sensory adaptation
The sensory law of adaptation refers to the phenomenon in which our sensory systems become
less sensitive to constant or repetitive stimuli over time. This means that as we are exposed to a
particular stimulus for an extended period, we may initially register it strongly but eventually
adapt to it to the point where we may no longer notice it. For example, the humming sound of
a refrigerator may be very noticeable when it first starts running, but over time, we may
become accustomed to the sound to the point where we no longer register it. This adaptation
makes it possible for our sensory systems to continually detect and respond to changes in our
environment, rather than becoming overwhelmed by constant stimuli.
Events or stimuli that you perceive clearly are the focus of your experience and other items or
stimuli that you perceive dimly or vaguely are in the margin of your attention.
Paying attention is in general a function of two factors. factors external to perceiver and factors
internal to perceiver.
Intensity- the more intense the stimulus the more it’ll be attended. E.g. the brighter light
is more attended than the dull one.
Size- the larger the size of the stimulus the more we give attention and the smaller the
size we give less attention.
Contrast- what contrasts with the surrounding environmentattracts attention easily. E.g.
if one stranger and teacher are enter in the class, the students give more attention to
the stranger and less attention for the teacher.
Movement- something, which moves, is more likely to attract attention than something
stationary.
Internal (psychological) factors affecting paying attention
Set or Expectancy
refers to mental readiness to receive certain kinds of sensory input
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EX: A husband expecting an important phone call is more likely to hear phone calls than
a wife who is concerned about her baby crying.
Motives or Needs
People are more likely to be attracted to environmental experiences ( events) in which
they7are interested.
• Personality and interest- individuals select the stimulus and give attention if they are
interested.
From perception
Form perception is the process of recognition of visual elements through the human eyes.
Perception by the human eye can differ for the same object depending on its position, angle of
vision, apparent size, eye frequency, and illumination level. Visual perception takes place
through various environmental stimuli. Form perception can be described which is based on the
gestalt principle which gives a rule by which the human eye can perceive an object properly.
Everything we perceive has its own structure and form. To make sense out of what we perceive,
we must know where one thing begins and another ends
This process of dividing up the world occurs effortlessly (naturally) and makes our perception
more meaningfull.
To perceive forms (meaningful shapes or patterns), you need to distinguish a figure (an object)
from its ground (or its surrounding).
Figure-Ground Perception
Figure-ground perception is the ability of the brain to distinguish an object from its background.
It is a fundamental visual processing skill and essential to human perception of the world. This
process involves determining which part of the visual field is the "figure" (the object of interest)
and which is the "ground" (the background or context that surrounds the figure). This
perception requires not only the ability to detect edges and contrasting visual information but
also the ability to interpret the context in which the object is presented. Figure-ground
perception is important in art, design, and everyday life, as it helps us to perceive visual
information and recognize objects and scenes.
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Contour refers to the outline or shape of an object. In form perception, contour plays a critical
role in identifying and distinguishing one object from another. The edge or contour of an object
provides information about its boundaries, depth, and surface characteristics. The human visual
system uses cues such as changes in contrast, curvature, and continuity to identify and separate
objects based on their contours. The perception of contour is an essential aspect of form
perception, which allows us to recognize and interpret the shapes and structures of the world
around us.
When several objects are present in the visual field, we tend to perceive them as organized into
patterns or groupings.
1. Law of Proximity: Elements that are close together are perceived as belonging together.
2. Law of Similarity: Elements that are similar to each other are perceived as belonging
together.
3. Law of Closure: When parts of a whole image are missing or incomplete, the brain fills in the
gaps to perceive a complete image.
4. Law of Continuation: Elements that form a smooth and continuous line or curve are
perceived as belonging together.
5. Law of Common Fate: Elements that move together are perceived as belonging together.
6. Law of Figure-Ground: The brain separates an image into a foreground (figure) and a
background (ground).
7. Law of Symmetry: The brain perceives objects as symmetrical and follows the symmetry
while grouping the objects together.
Depth perception
Depth perception: perceived by using a number of cues
a. Binocular disparity: takes account of the disparate images of each retina; a depth cue
resulting from slightly different images produced by the retina of the left eye and the retina of
the right eye .
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2. Monocular cues: depth cues provided by one eye
a. Motion parallax is the phenomenon where near objects are seen as moving more rapidly
than far objects when the viewer’s head is moving.
b. Texture gradient is when the texture of a surface receding in the distance changes in clarity,
blurring at further distances.
e. Relative height: Objects higher in the perceptual field are farther away.
3. An occulomotor cue is a depth cue based on our ability to sense the tension in our eye
muscles and the position of our eyes.
a. Accommodation
b. Convergence is the name of the cue that takes account of the muscle tension resulting from
external eye muscles that control eye movement. Convergence is sometimes classified as a
binocular cue since it requires both eyes.
Perceptual illusion
A perceptual illusion is an experience in which a stimulus is perceived differently from reality.
That is, the way the brain processes and interprets sensory information can sometimes lead to
false or distorted perceptions of objects or events in the world. Perceptual illusions can be
caused by a variety of factors, including physical properties of the stimulus itself, cognitive
biases, or perceptual processing errors in the brain. Common examples of perceptual illusions
include optical illusions, auditory illusions, and tactile illusions
o Auditory illusions
• Are false perceptions of a real sound or outside stimulus.
• The listener hears either sounds which are not present in the stimulus, or sounds that
should not be possible given the circumstance on how they9were created.
o Optical Illusions
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• can use color, light and patterns to create images that can be deceptive or misleading
to our brains.
• The information gathered by the eye is processed by the brain, creating a perception
that in reality, does not match the true image.10
Extra sensory perception
Extra sensory perception (ESP) refers to the ability to perceive information beyond the five
physical senses (sight, hearing, touch, taste, and smell). ESP includes several abilities such as
telepathy (the ability to read another person's thoughts), clairvoyance (the ability to see events
or objects from a distance), precognition (the ability to predict future events), psychokinesis
(the ability to move objects with one's mind), and intuition (the ability to understand or know
something without conscious reasoning). There is much debate and skepticism surrounding
ESP, as scientific evidence for its existence is inconclusive.
Sensation refers to the process of receiving information from the environment through
our five senses (sight, hearing, taste, touch, smell).
Perception, on the other hand, is the process of interpreting and organizing the sensory
information we receive to make sense of it.
Sensation is a physiological process that occurs in response to a stimulus, while
perception is a mental and subjective process that involves assigning meaning and
significance to the information sensory.
Sensation is a basic process that involves identifying and recognizing the nature and
characteristics a of stimulus, while perception a is more complex process that involves,
cognition memory, and interpretation.
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In summary, sensation is the first step in the of process perceiving world the around us while,
perception involves making sense of and interpreting the sensory information we receive.
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