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Introductory Psychology

Module 5:

Sensation and Perception

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Affirmations

I can help someone else today
I have a sharp mind that makes me a very good student
There is no reason for me to compare myself to others

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Recall

How would you define consciousness?
How do the various stages of sleep, including REM and NREM stages, differ in brain wave activity and physiological function?
Can you identify and describe at least three common sleep disorders, and explain how they might impact overall health and well-being?
What are some strategies for improving sleep quality?

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Key Integrative Theme

Theme C: Psychological, biological, social, and cultural factors influence behavior and mental processes.

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Two Truths and a Lie

Which of these is the lie?

C. The human auditory system is remarkably simple.

B. Sensory information can be processed consciously or unconsciously.

A. The tips of your fingers are much more sensitive to touch than are your elbows.

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Activity: Have students identify the false statement from this grouping.

Answer: The human auditory system is remarkably complex, not simple.

The auditory system involves intricate processes that allow us to detect, recognize, and interpret sounds. Starting from the outer ear, where sound waves are captured, to the middle ear, where they are amplified, and then to the inner ear, where they are translated into electrical signals, the system is finely tuned and highly specialized.

Once the sound waves are converted into electrical signals, they travel along the auditory nerve to the brain, where they are processed in the auditory cortex. This allows us to recognize different types of sounds, understand speech, and even locate the direction of a sound source.

The fingertips have a high concentration of nerve endings, making them much more sensitive to touch compared to areas like the elbows.

In reality, a lot of sensory information is processed subconsciously or unconsciously. The brain filters out a significant amount of sensory information to prevent overload, and only the most relevant information reaches our conscious awareness.

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Section 1 Learning Goals

1 Define sensation

2 Define perception

Deepen your understanding and form connections within these skills:

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Sensation

Sensory information

Includes vision, hearing, smell, taste, touch, balance, body position, movement, pain, and temperature

Absolute threshold: the minimum amount of stimulus energy that must be present for the stimulus to be detected 50% of the time.
Messages that are presented below the threshold for conscious awareness are called subliminal messages.
Difference threshold: Weber’s Law: The difference threshold is a constant fraction of the original stimulus

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�Candle in the dark. Authored by: pratanti. Located at: https://www.flickr.com/photos/pratanti/3631956828. Project: Flickr. License: CC BY: Attribution

Absolute threshold refers to the minimum amount of stimulus energy that must be present for the stimulus to be detected 50% of the time.

It is also possible for us to get messages that are presented below the threshold for conscious awareness—these are called subliminal messages. A stimulus reaches a physiological threshold when it is strong enough to excite sensory receptors and send nerve impulses to the brain: This is an absolute threshold. A message below that threshold is said to be subliminal: We receive it, but we are not consciously aware of it. Over the years there has been a great deal of speculation about the use of subliminal messages in advertising, rock music, and self-help audio programs. Research evidence shows that in laboratory settings, people can process and respond to information outside of awareness. But this does not mean that we obey these messages like zombies; in fact, hidden messages have little effect on behavior outside the laboratory (Kunst-Wilson & Zajonc, 1980; Rensink, 2004; Nelson, 2008; Radel, Sarrazin, Legrain, & Gobancé, 2009; Loersch, Durso, & Petty, 2013).

Weber’s law: The difference threshold is a constant fraction of the original stimulus, as the example illustrates.

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Perception

How sensory information is interpreted and consciously experienced
Sensation is a physical process, whereas perception is psychological
Bottom-up processing refers to sensory information from a stimulus in the environment driving a process, and top-down processing refers to knowledge and expectancy driving a process,
Attention and motivation determine what is sensed versus what is perceived
Sensory adaptation

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The Importance of Attention

Attention plays a significant role in determining what is sensed versus what is perceived.

Inattentional blindness is the failure to notice something that is completely visible because the person was actively attending to something else and did not pay attention to other things

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Top-Down vs. Bottom-Up Processing

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Activity: Understanding Senses

A. Imagine that you are performing a specific action in a specific environment (e.g., sipping on lemonade at the beach, shopping at a grocery store, etc.).

B. Write down a few words or very brief descriptions to describe the sensations that you would be experiencing at that moment in time. Try to think of at least one word/description for each basic sense.

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Activity #3 from instructor resources: https://docs.google.com/document/d/11mVplD64Miw1SjXklToJKIdEDs4TTBoDTzlf0oIjUj4/edit

Sample: For example, if you are imagining sipping on lemonade at the beach, you might write down “sweet and sour” for the sense of taste, “saline” for the sense of smell, “cooling down” and “sandy” for the sense of touch, “lots of light” and “blue” for the sense of sight, and “rumbling, crashing sounds” for the sense of hearing. The intention here is to try and isolate individual sensations experienced during an event without relying on our perceptual knowledge of what things/items are. This means that in this example, instead of saying “ocean” for the sense of sight, break down the visual attributes of the ocean such as “blue”, “rippling”, and “sparkling” to describe the ocean. It might feel tedious to break things down into such basic sensations, but our bodies are constantly using all of these types of basic sensory inputs to contribute to our perceptual knowledge of the world!

�Next steps: Then, turn to a partner, and simply list the different sensations and their respective senses. Try and see if you both can guess, based on these sensations alone, what the whole event is. Chances are, identifying the whole event from a limited set of identified parts will be difficult (although you may have been on the right track)! Lots of sensation inputs can contribute to our perception of complex events, and examining these pieces of information in isolation may not lend itself to accuracy.

�Discussion: When perceiving whole events, we tend to use multimodal perception – that is, perception that is aided by various sensory inputs. In this activity, you were asked to consider the sensations experienced by the basic senses as pieces of unimodal stimuli that were then pieced together by your partner in an attempt to simulate multimodal perception (i.e., create the “whole” from the sum of its parts). However, you and your partner might have experienced some difficulty in precisely identifying a complex event, as there can be many sensory inputs involved in even the simplest of scenarios.

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Apply It

Imagine that you are at a party with lots of people, noise, and activity. Suddenly, from across the room, you hear something that sounds like your name. ��Has this ever happened to you? If so, how were you able to attend to this information even though so much other information was competing with it?

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On the Apply It page, students learn about dichotic listening and Broadbent’s selective filter theory, and how sensory information is filtered, leading to perception. It turns out, stimuli relevance is one thing that can help information pass through the bottleneck (Schäfer et al., 2020).

From the page: Psychologist Donald Broadbent (1958) proposed a selective filter theory to help explain why we attend to some information and filter out other information. According to this selective filter theory, our ability to perceive information operates like a bottleneck.

Bottle showing how lots of sensory inputs funnel like through the base of a bottle and then only some is attended to, like those at the neck of the bottle.

Numerous sensory inputs enter the broadest part of the “bottle”, representing everything our body can sense at a given time. However, our perceptual store is limited, and cannot process all of that information, so sensory information must be filtered through the much more narrow “neck” of the bottle. Thus, few sensory inputs actually make it through.[1]

Related to this theory, Broadbent (1958) developed the dichotic listening task, in which people must attend and respond to stimuli broadcasted in one ear while ignoring the information broadcasted in the other.

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The Stroop Test

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Bottom-Up Processing: This refers to the automatic, data-driven processing that starts with sensory input and moves upwards to higher-level cognitive functions. In the Stroop test, reading the word is a highly practiced and automatic process that typically occurs without conscious effort, representing bottom-up processing. When you see the word "blue" your brain automatically reads it, even if you're trying to focus on the color of the ink.

Top-Down Processing: This involves cognitive processes guided by higher-level mental processes, such as prior knowledge, expectations, and goals. In the Stroop test, top-down processing is required to suppress the automatic tendency to read the word and instead focus on naming the ink color, which is the task goal. This requires attentional control and cognitive flexibility.

Attention: The Stroop test is particularly insightful for understanding selective attention, which is the ability to focus on relevant stimuli while ignoring irrelevant information. In the case of incongruent stimuli, participants must actively direct their attention away from the automatic reading of the word to concentrate on the color of the ink, demonstrating the role of attention in managing conflicting information.

The Stroop effect, which is the delay in reaction time and increase in errors when dealing with incongruent stimuli, highlights the competition between bottom-up and top-down processes. It shows how our cognitive system prioritizes highly practiced tasks (like reading) and how top-down control is needed to override these automatic responses when they conflict with our current goals.

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Section 2 Learning Goals

1 Describe the anatomy of the visual system

2 Understand how light waves are related to vision

3 Describe the main theories about color vision

4 Understand monocular and binocular cues and the perception of depth

Deepen your understanding and form connections within these skills:

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Anatomy of Vision

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Photoreceptors in the Fovia Detect Light

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From Eye to Brain

Note the optic nerve, optic chiasm and the pathways to the occipital lobe, where visual sensations are processed into perceptions

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Once inside the brain, visual information is sent via a number of structures to the occipital lobe at the back of the brain for processing. Visual information might be processed in parallel pathways which can generally be described as the “what pathway” and the “where/how” pathway. The “what pathway” is involved in object recognition and identification, while the “where/how pathway” is involved with location in space and how one might interact with a particular visual stimulus (Milner & Goodale, 2008; Ungerleider & Haxby, 1994). For example, when you see a ball rolling down the street, the “what pathway” identifies what the object is, and the “where/how pathway” identifies its location or movement in space.

Vision, Waves and Wavelengths. Authored by: OpenStax College. Located at: http://cnx.org/contents/Sr8Ev5Og@5.49:E-7sLQFP@5/Vision. License: CC BY: Attribution. License Terms: Download for free at http://cnx.org/content/col11629/latest/.

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Visual Information in the Brain

Visual information is processed in parallel pathways which can generally be described as the “what pathway” (the ventral pathway) and the “where/how” pathway (the dorsal pathway)

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Light Waves and the Electromagnetic Spectrum

Light enters the eye as a wave

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The Visible Spectrum

Different wavelengths of light are associated with our perception of different colors

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Two Theories of How We See Color

Trichromatic

The cones respond to three wavelengths that represent red, blue, and green.
All colors can be produced by combining red, blue, and green.
Applies to visual processing on the retina

Opponent Process

Color is coded in opponent pairs: black-white, yellow-blue, and green-red.
Cells of the visual system are excited by one of the opponent colors and inhibited by the other.
Explains why we can’t see greenish-red and why there are afterimages.
Applies once the signal moves past the retina on its way to the brain

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How We See Color-Trichromatic Theory

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Opponent-Process Theory

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Depth Perception

Depth perception: ability to perceive spatial relationships in (3-D) space
Binocular cues
Monocular cues

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Vision Perception

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Section 3 Learning Goals

1 Describe the anatomy of the auditory system

2 Understand how sound waves shape our hearing

3 Explain how we perceive pitch and localize sound

4 Describe types of hearing loss

Deepen your understanding and form connections within these skills:

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Anatomy of the Auditory System

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Sound Waves

Sound waves travel into our ears at various speeds and amplitudes
Higher amplitudes are associated with louder sounds
High-frequency sound waves are perceived as high-pitched sounds

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How We Hear

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Two Theories of Pitch Perception

Temporal

Frequency is coded by the activity level of a sensory neuron.
Applies to frequencies of up to 4000 Hz

Place

Different portions of the basilar membrane are sensitive to sounds of different frequencies
Place contributes to pitch perception for frequencies under 4000 Hz.
Much higher frequency sounds can only be encoded using place cues.

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Sound Localization

Monaural (one-eared) Each pinna interacts with incoming sound waves differently, depending on the sound’s source relative to our bodies.

Binaural (two-eared) cues:

Interaural level difference
Interaural timing difference

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Types of Hearing Loss

Deafness
Congenital deafness
Conductive hearing loss
Sensorineural hearing loss

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Apply It: Hearing

The Mosquito is one example of how communities and groups have sought to use design to exclude certain groups of people. This practice is commonly done in the design world through something known as hostile architecture.
High-frequency hearing test: https://www.scientificamerican.com/article/bring-science-home-high-frequency-hearing/

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Apply It: Hearing

Can you identify any examples of hostile architecture in your local community? What behaviors do you think these designs are intended to deter?
How might the implementation of hostile architecture affect the mental health of individuals in the community, particularly those who are targeted by these design elements?
How can the principles of inclusive design counteract the negative psychological impacts of hostile architecture? Can you think of an example of how inclusive design might be implemented in a public space?

Reflecting on “The Mosquito” device and examples of hostile architecture, what does this tell you about the role of perception and sensation in our interactions with the environment?

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Spiked Ledge

These spikes prevent passersby from

sleeping or sitting on the ledge in Boston.

Spiked Ledge Boston. Authored by: Paydah. Located at: https://commons.wikimedia.org/wiki/File:Spiked_Ledge_Boston.jpg. Repository: Wikimedia Commons. License: CC BY-SA: Attribution-ShareAlike

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Grind Prevention

These stoppers halt skateboarders in their tracks if they try to grind on the ledge.

Grind Prevention. No machine-readable author provided. Located at: https://commons.wikimedia.org/wiki/File:Grind-prevention.jpg. Repository: Wikimedia Commons. License: CC0: Public Domain

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Boulder

Deterrents

In Portland, OR, these huge boulders make sleeping uncomfortable for any transient campers.

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Odot Boulder. Authored by: Graywalls. Located at: https://commons.wikimedia.org/wiki/File:Odot_boulder.jpg. Repository: Wikimedia Commons. License: CC BY-SA: Attribution-ShareAlike

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Hostile

Benches

At a train station in Vienna, Austria these long metal pipes fend off anyone who wants to sleep on the benches.

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Westbahnhof, hostile benches 02. Authored by: Herzi Pinki. Located at: https://commons.wikimedia.org/wiki/File:Westbahnhof,_hostile_benches_02.jpg. Repository: Wikimedia Commons. License: CC BY-SA: Attribution-ShareAlike

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Boulons

Anti-homeless metal bolts are placed on doorways to discourage all types of loitering on the steps in Marseille, France.

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Boulons anti-sdf sur un perron (Marseille, France). Authored by: DocteurCosmos (DC). Located at: https://commons.wikimedia.org/wiki/File:Boulons_anti-sdf_sur_un_perron_(Marseille,_France).jpg. Repository: Wikimedia Commons. License: CC BY-SA: Attribution-ShareAlike

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Section 4 Learning Goals

1 Explain taste and smell as chemical senses

2 Describe the receptors that respond to touch

3 Discuss the experience of pain

4 Describe the basic functions of the vestibular, proprioceptive, and kinesthetic sensory systems

Deepen your understanding and form connections within these skills:

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Taste

Molecules from the food and beverages we consume dissolve in our saliva and interact with taste receptors on our tongue (below) and in our mouth and throat

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Smell

Olfactory receptors are proteins with pockets that identify molecules of chemicals in the air. This information is transmitted from the olfactory bulb to the brain.

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Touch

Specific receptors in the skin convert stimulation to electrical nerve impulses, a process called transduction

Mechanoreceptors (below) respond to mechanical stimuli, such as stroking, stretching, or vibration of the skin
Thermoreceptors respond to cold or hot temperatures
Chemoreceptors respond to certain types of chemicals either applied externally or released within the skin

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Pain

Pain is adaptive because it makes us aware of an injury, and it motivates us to remove ourselves from the cause of that injury

Neuropathic pain
Inflammatory pain
Nociceptors are subtypes of chemoreceptors or mechanoreceptors that fire specifically to potentially tissue-damaging stimuli

Expectations and context shape how we experience pain

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Pain and the Somatosensory Cortex

Pain is signaled via fast-conducting A-fibers, which project to the somatosensory cortex

This part of the cortex is somatotopically organized—that is, the sensory signals are represented according to where in the body they stem from

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Pain Processing Pathways

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The Vestibular System

The major sensory organs of the vestibular system are located next to the cochlea in the inner ear

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	Definition	Example
Vestibular Sense	Sensory system that contributes to balance and the sense of spatial orientation.	You have an ear infection and feel dizzy.
Propioception	Perception of body position.	You step off a curb and know where to put your foot. You push an elevator button and control how hard you have to press down with your fingers.
Kinesthesia	Perception of the body’s movement �Key component in muscle m emory and hand-eye coordination.	You are aware of your arm movement while swinging a golf club.

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Section 5 Learning Goals

1 Describe examples of Gestalt principles

2 Understand multimodal perception

3 Give examples of multimodal and crossmodal behavioral effects

4 Explain how and why psychologists use illusions

5 Discuss real-life examples of the Ebbinghaus illusion

Deepen your understanding and form connections within these skills:

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Gestalt Principles of Perception

The brain creates a perception that is more than simply the sum of available sensory inputs

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Figure-Ground Relationship

The concept of figure-ground relationship explains why this image can be perceived either as a vase or as a pair of faces

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Proximity

The Gestalt principle of proximity suggests that you see (a) one block of dots on the left side and (b) three columns on the right side

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Similarity

When looking at this array of dots, we likely perceive alternating rows of colors

We are grouping these dots according to the principle of similarity

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Continuation

Continuation would suggest that we are more likely to perceive this as two overlapping lines, rather than four lines meeting in the center

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Closure

Closure suggests that we will perceive a complete circle and rectangle rather than a series of segments

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Multimodal Perception

Multimodal perception is the effect stimulation of multiple senses has on perception.

Multimodal phenomena

McGurk Effect
Rubber Hand Illusion

Crossmodal phenomena

Double flash illusion
Ventriloquism effect

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Why Do Psychologists Use Illusions?

Perception scientists create illusions to explore perception, what parts of the brain are involved in interpretation of the illusion, and what variables increase or diminish the strength of the illusion.

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Section 4 Apply It: Illusions

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(Image from https://en.wikipedia.org/wiki/Delboeuf_illusion)

Which circle looks bigger?

Activity #2:

Having already learned about the Ebbinghaus illusion, you were probably right in guessing that the circle with the ring around it appears larger than the non-surrounded circle. This is an example of the Delboeuf illusion, first identified by Belgian philosopher and mathematician Joseph Delbouef in 1887 or 1888. Modern psychologists have tested this illusion in various experiments, including one to determine if eyeshadow makes eyes look bigger (it does), and others to determine if the quantity of food on a plate looks larger if the plate is smaller.

Studies by Koert Van Ittersum and Brian Wansink at the Cornell Food and Brand Lab have studied the effect of the Delbouef illusion on eating and serving behavior. In several different experiments, they measured if people would take more or less than a typical serving size depending on the size of their plate, the color of the plate, the color of the tablecloth, and how much they knew about the Delboeuf illusion.

*Note that research by Brian Wansink has been called into question following some significant errors and deceptive results presented in his publications. Since 2017, 17 of his papers were retracted and 15 were revised after it came to light that some of the data had been manipulated. This study was not one of those called into question, but it may impact the way you present this research.

You will need access to the article “Plate Size and Color Suggestibility: The Delboeuf illusion’s bias on eating and serving behavior” by Koert Van Ittersum and Brian Wansink

Van Ittersum, K., & Wansink, B. (2012). Plate Size and Color Suggestibility: The Delboeuf Illusion’s Bias on Serving and Eating Behavior. Journal of Consumer Research, 39(2), 215-228. https://doi.org/10.1086/662615

AND/OR

McClain, A., Matheson, D., Desai, M., McClure, S. M., & Robinson, T. N. (2014). Visual illusions and plate design: The effects of plate rim widths and rim coloring on perceived food portion size. International journal of obesity (2005), 38(5), 657. https://doi.org/10.1038/ijo.2013.169: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3947396/

Divide class into groups of 2 or 3 students�Have students read through the study, “Plate Size and Color Suggestibility: The Delboeuf illusion’s bias on eating and serving behavior” by Koert Van Ittersum and Brian Wansink. You can find the full article by searching online or using your library's database.
Present the scenario�Tell students that they are either 1) In charge of a family reunion 2) planning a wedding 3) preparing for a social banquet of some sort (they can use their imagination), and expected to feed approximately 100 to 150 people. �Their group is in charge of providing meals at the event and are worried about not having enough linguini alfredo (a white pasta) to serve everyone. You want to ensure that no one takes too much food.
Strategize�Give the students the following instructions:

As a group, create a plan for the event. Include advice on what size plates you should use, what color they should be, and what color tablecloths you should buy. ��Cite specific pieces of evidence (at least four quantitative examples) from the research study, about why you made the decisions that you did. Explain how you can utilize the Delboeuf illusion to minimize costs at the reunion.

Share�Have students pitch their idea to the rest of the class.

Discussion

Based on your understanding of the Delboeuf illusion and the findings in the study by Ittersum and Wansink, what are some potential drawbacks or ethical considerations when using this psychological phenomenon to influence people's behavior in terms of food consumption?
The study examined the effect of the Delboeuf illusion on serving and eating behavior. Can you think of any other everyday situations where this illusion might have significant impact, either positively or negatively?
We've discussed how research findings can sometimes be called into question or retracted, as mentioned in the footnote about Brian Wansink's research. What does this teach us about the scientific process and the importance of skepticism and verification in psychology?
Besides the Delboeuf illusion, can you think of other psychological principles or phenomena that could potentially be used to influence people's food consumption behavior? How could these be applied ethically and effectively?

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Activity: Fun with Forced Perspective

Can you create your own example of forced perspective?

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Activity #1 from the instructor resources: https://docs.google.com/document/d/11mVplD64Miw1SjXklToJKIdEDs4TTBoDTzlf0oIjUj4/edit

Define forced perspective�Begin by introducing students to the concept of forced perspective. Forced perspective is an optical illusion technique used in photography, film, and architecture to manipulate human perception by making objects appear to be larger, smaller, closer, or farther away than they actually are.

Supplement this description with an image(s) of what forced perspective might look like, or a video like this one: Forced Perspective Photography Tutorial | Beginner

Explain instructions�Assign students to groups and inform them that at least one person will need to use a cell phone or tablet capable of taking photos for this activity. ��Groups must identify an object in the classroom and take at least two photos using forced perspective to manipulate how this object might be perceived. Encourage students to be creative!

Discussion

Which object did you manipulate and how did you manipulate it?
Name and describe two Gestalt principles that were impacted by the manipulation.
How can the use of forced perspective meaningfully impact human perception in everyday life?

Debrief

In this activity, you were able to use the Gestalt principles to manipulate the way that the world is perceived. Forced perspective visual illusions like the ones you just created are used all the time in photography, film, and architecture, but some visual illusions occur without anyone’s intention to manipulate the senses. For instance, mountains and hills that are quite a distance from one another might appear to be closer together when they are viewed from a certain height or distance. What are some visual illusions (either created by humans or naturally existing) that you have experienced?

People in Western cultures, for example, have a perceptual context of buildings with straight lines, what Segall’s study called a carpentered world (Segall et al., 1966). In contrast, people from certain non-Western cultures with an uncarpentered view, such as the Zulu of South Africa, whose villages are made up of round huts arranged in circles, are less susceptible to this illusion (Segall et al., 1999). It is not just vision that is affected by cultural factors. Indeed, research has demonstrated that the ability to identify an odor, and rate its pleasantness and its intensity, varies cross-culturally (Ayabe-Kanamura, Saito, Distel, Martínez-Gómez, & Hudson, 1998).

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Quick Review

What is the difference between sensation and perception?
How does vision work?
How do people see color and depth?
How does hearing work?
What are the basic anatomy and functions of taste, smell, touch, pain, and the vestibular sense?
What is perception?
What are some examples of gestalt principles and multimodal perception?

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Attributions

Illustrations are from Storyset
Images from Pexels & Unsplash
Add additional attributions here……
Remember to add image alt text

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