This document discusses sensation, perception, and abnormalities of perception from a psychological perspective. It defines sensation as our sense organs capturing stimuli from the environment and transmitting those stimuli as electrical signals to the brain. It then discusses the five traditional senses - sight, hearing, smell, taste, and touch - in more detail. It defines perception as the process of organizing and interpreting sensory information to create meaningful experiences, noting it involves factors like attention, past experiences, and emotions. It also outlines some factors that can influence perception, like motivation, emotions, individual differences, context, and stimulus characteristics. It concludes by briefly discussing abnormalities of perception like illusions, hallucinations, and proposals of extrassensory perception, but noting a lack of strong

1. 1865 – custodian care hospital a subculture of Sindh

2. 1. Sensation and sense organs
2. Perception
Dr. Muhammad Raza Memon
MBBS, DPM, Dip-CBT, MD Psych
Senior Registrar of Psychiatry
Liaquat University of Medical & Health Sciences,
Jamshoro
UNDERSTAND HUMAN BEHAVIOR THROUGH
THE PRINCIPLES OF PSYCHOLOGY

3. Sensation: Our Gateway to the
World
 Our Sense Organs act as gateways, capturing stimuli
from the environment.
 Five sense organs are specialized structures
responsible for transuding external stimuli into electrical
signals the brain can interpret.
Eyes: convert light into electrical signals for vision.
Ears: convert sound waves into electrical signals for
hearing.
Nose: detects chemicals in the air for smell.
Tongue: detects chemicals in food for taste.
Skin: detects pressure, temperature, pain, and touch.

4. From Pixels to Meaning: The Visual
Journey
Our eyes receive light waves:
Photoreceptor cells in the retina (rods and cones)
convert light into electrical signals.
 Rods: Sensitive to low light, enable black and white
vision.
 Cones: Sensitive to bright light and color vision.
The brain takes over:
 Visual cortex interprets the signals, creating our
perception of sight.
 This includes depth perception, object
recognition, and motion detection.

5. The Symphony of Sounds: Hearing
more than just Noise
Sound waves enter the ear:
 Travel through the ear canal and vibrate the eardrum.
 These vibrations are transmitted to tiny hair cells in
the cochlea, generating electrical signals.
The brain conducts the orchestra:
 Auditory cortex interprets the signals, allowing us to
hear and understand sounds.
 This includes recognizing pitch, rhythm, and even the
speaker's voice.

6. The Touchy Subject: Feeling beyond
Skin Deep
Touch receptors all over:
 Located in skin, muscles, and joints, detecting
pressure, temperature, and texture.
More than just physical:
 Touch conveys emotions, comfort, and social
connection.
 It plays a crucial role in early development and
social bonding.

8. The Lens of Perception
 Perception: The process of organizing and interpreting
sensory information to create meaningful experiences.
 More than just sensation: Perception involves
selection, attention, and interpretation of sensory
information, influenced by past experiences,
expectations, and emotions.
 Examples:
 Seeing a friend in a crowded room – your brain filters out
other stimuli to focus on their specific features.
 Feeling the warmth of the sun – your brain interprets the
skin sensation as pleasant warmth.
 Tasting a dish – your brain integrates taste, smell, and
texture to create a unique flavor experience.

9. Five Major Functions of the Perceptual
System
1. Attention: Determining which part of the sensory
environment to pay attention to
2. Localization: Localizing where objects are
3. Recognition: Identifying what objects are
4. Abstraction: Extracting the critical information
from objects
5. Constancy: Maintaining the appearance of
objects constant. (even though their retinal images
are changing)

12. FACTORS AFFECTING PERCEPTION
The Big Three: Internal Factors
 Motivation: Our desires and needs influence what we
notice and how we interpret it.
A thirsty person might see a mirage as an oasis.
 Emotions: Positive emotions can enhance
perception, while negative emotions can narrow it.
Feeling stressed might make it harder to focus on details.
 Individual Differences: Our unique personalities,
experiences, experiences, and biases shape our
perception. Two people may witness the same event but
have very different interpretations.

13. FACTORS AFFECTING PERCEPTION
The External World: Shaping Our View
 Context: The situation surrounding an object or event
influences how we perceive it. A loud noise in a library
might seem disruptive, but not at a concert.
 Stimulus Characteristics: Features like size, color, and
intensity can grab our attention and influence our
interpretation. A flashing red light is hard to ignore.
 Prior Knowledge and Expectations: What we already
know and what we expect to see can shape our
perception. Seeing a familiar face in a crowd might feel like
confirmation bias.

15. ABNORMALITIES OF PERCEPTION
 ILLUSIONS:
An illusion is a misperception of a real external
stimulus. Perception involves the brain's attempt
to interpret and make sense of the stimuli we
receive from our environment.
 Illusions are often seen in patients in intensive
care units, such as those in an acute
confusional state or delirium, as well as people
under the influence of alcohol and drugs such
as LSD.

17. ABNORMALITIES OF PERCEPTION
 HALLUCINATIONS:
Hallucinations are perceptions without any
external stimulus. They can involve any of the
five senses, but the most common are auditory
and visual.
 They are most commonly seen in patients with
serious mental illnesses, such as schizophrenia.
The most common cause of visual
hallucinations is delirium tremens.

18. EXTRASENSORY PERCEPTION (ESP)
 The occurrence of experiences or behaviours in the
absence of an adequate stimulus.
 Considered to be paranormal or beyond our normal
sensory abilities and are studied in parapsychology.
ESP includes the phenomena of:
 Clairvoyance: The ability to perceive events or gain
information in ways that appear unaffected by distance
or normal physical barriers.
 Telepathy: Extrasensory perception of another
person’s thoughts or in other words the ability to read
someone’s mind.

19. EXTRASENSORY PERCEPTION (ESP)
 Precognition: The ability to perceive or accurately predict
future events. Thus prophecies and prophetic dreams
about the future are included in precognitions.
 Telekinesis: This phenomenon studied by
parapsychologists is basically the ability to move objects
at a distance by mental power or other non-physical
means
To date there is little scientific evidence to prove the
existence of extrasensory perceptions

20. For Contact:
email: muhammad.raza@lumhs.edu.pk