Processing the Environment Flashcards
Clinicians will see large amounts of data (labs results, patient symptoms, etc) over the course of their practice, and their brains will subconsciously group that data along certain established principles. Awareness of this underlying mechanism will help clinicians identify potential bias and provide better care. Which of the following best explains the Gestalt principles of grouping?
The mind processes the whole rather than the sum of its parts
While invariance, reification, and multistability are important concepts of perception, listing them does not explain the principle of Gestalt grouping.
One of the observations that led to the principles is that we tend to process reality in its simplest form. However, the overarching theory of Gestalt grouping combines this observation with several others to explain how we process the world around us.
Gestalt psychology states that the mind processes the whole of a perception rather than the sum of its parts, but makes no value judgement about more or less than.
Meningitis and the flu share many early symptoms. Which of the following could explain why a doctor could misdiagnose meningitis as the flu during flu season?
Gestalt principle of similarity
A high signal detection threshold (loosening the criteria for meningitis) would mean that the doctor would be more likely to diagnose meningitis.
Bottom-up information processing means that the doctor would start with no prior knowledge and create the diagnosis only from information gained from the patient. This would block the confounding caused by flu season, and be more likely to lead to the correct diagnosis.
The just noticeable difference refers to the amount of change required to register in one’s perception of a stimulus. If the doctors had a low just noticeable difference to distinguish flu from meningitis, they would be more likely to notice that their patient had a more serious disease and address that concern.
The Gestalt principle of similarity would explain why the similar symptoms of flu and meningitis would be grouped in the doctor’s mind, potentially leading to a misdiagnosis.
Repeated administration of some drugs will lead to a decrease in their effectiveness, an occurrence known as drug tolerance. When this occurs, doctors may need to increase the dosage in order to continue therapy. What is true of this increase?
The dosage increase is directly proportional to the initial dose
The doctor will attempt to increase the dosage by the just noticeable difference, in order to maintain the drug’s effects while avoiding toxicity.
Different individuals will react to drugs differently, and so each person will have their own threshold for drug tolerance.
The dosage increase is directly proportional to the initial dose - Weber’s Law states that the difference threshold divided by the initial stimulus is a constant for that person.
A diagnostic test is developed for a potentially fatal disease. In order to effectively treat the disease, those diagnosed with it must immediately be placed on a costly and poorly tolerated medication. Which threshold should be used for this test?
a liberal strategy which would make sure everyone with the disease was treated
Signal detection theory is a way to make decisions when faced with uncertainty.
There are negative consequences for both false positives and false negatives.
In the case of a fatal disease with an effective treatment, it is best to err on the side of caution and adopt a liberal detection strategy which would ensure treatment for every affected patient.
Diplopia is the scientific term for double vision, a condition in which the patient perceives two images of the same entity, usually displaced horizontally or vertically. Which of the following perceptual cues is most affected by diplopia?
Convergence
Monocular cues, such as motion parallax and interposition, would not be affected by diplopia.
Binocular disparity relies on the different images seen by each eye to determine depth, but still takes each image as a separate piece of information.
Convergence relies on both eyes working together to create a single image that helps to determine depth. Patients suffering from diplopia will have impaired depth perception due to the loss of this mechanism.
Which of the following is an example of sensory desensitization?
Getting used to a smell after being around it for hours
Sensory desensitization is an adaptive response.
Eating too much and feeling queasy is more an example of classical conditioning, a form of learning, than sensitization (a reflex).
Getting used to a smell after being around it for hours happens because the receptors in your nose become accustomed to the odor molecules and downregulate their response to them.
A patient is experiencing chest pain and sees several specialists. The cardiologist is worried about a heart attack and orders an echocardiogram, while the pulmonologist orders a lung capacity test. What perceptual organization principles are these doctors exhibiting?
Top-down processing
The doctors in this scenario are specialists whose expertise affects the way they view their patient.
The doctors’ expertise is information they bring with them before approaching the problem, so they are not using bottom-up processing.
The law of continuity holds that lines follow the smoothest path, so it may be applied to explain how the doctors think the disease is progressing, but cannot explain why they approach the problem differently.
The law of pragnanz states that we reduce reality to its simplest form. This could explain why doctors like to look for one diagnosis that covers all symptoms, rather than assuming a patient has a myriad of different disorders. However, it would not account for the specialists ordering different exams.
Top-down processing relies on prior knowledge to guide perception, which is what happens in this situation.
Which of the following would trigger high frequency firing from a non-adapting mechanoreceptor?
Mechanoreceptors sense pressure, so they would not register a sharp chemical pain like lemon juice on a paper cut, or nerve pain like touching a hot stove.
Stumbling after tripping on the curb would affect sensors that deal with proprioception and balance, but would not trigger a lot of firing from pain receptors as the stimulus would quickly clear.
A higher frequency correlates to a higher intensity stimulus.
Walking into a lamp post would be the most likely scenario to trigger high frequency firing from a mechanoreceptor.
Which of the following best exemplifies the Gestalt principles of grouping?
- A patient with the flu thinking they have meningitis because the symptoms are similar.
- A medical student scheduling classes in the morning and labs in the afternoon.
- A hospital breaking up departments into Cardiology, Infectious Disease, etc.
- A doctor making a diagnosis based on all of the symptoms a patient presents with.
The Gestalt principles of grouping hold that the brain process the whole, rather than the sum of its parts.
The principles of grouping focus on the whole, rather than the parts, so any example of breaking up into parts (classes, departments, etc), is not an example of Gestalt grouping.
The doctor who processes all of the information about a patient (labs, physical exam, medical history, etc) is using all of the information to create a single diagnosis. This exemplifies Gestalt grouping, as opposed to jumping to conclusions from a single blood test or physical symptom.
Which of these is the correct order to the steps of the phototransduction cascade in reaction to light?
A rod turns from on to off => turns a bipolar cell ON-center
Retinal changes confirmation => α unit bonds with PDE => the rod hyperpolarizes and turns OFF.
A rod turns from on to off => turns a bipolar cell on-center => activates a retinal ganglion cell.
The blind spot is the area where the optic nerve connects to the retina. The ‘night blind spot’ occurs under conditions of low light and can extend 5 to 10 degrees from the center of the person’s field of view. What is the cause of the ‘night blind spot’?
Photopic vision occurs at levels of high light levels.
Mesopic vision occurs at dawn or dusk and involves both rods and cones.
Scotopic vision occurs at levels of very low light.
The fovea is dense with cones and does not contain rods.
Scotopic vision, used in low light, does not receive input from the fovea due to the lack of rods.
Scientists selectively reared kittens in either an environment with lines of only vertical or only horizontal orientation. After 5 months, the scientists recorded from neurons in the cats’ cortex and found many neurons which responded to vertical lines in vertically reared cats, but no neurons that fired to horizontally oriented lines. The opposite occurred in horizontally reared cats; Horizontally reared cats had many neurons that responded to horizontal lines, but none that responded to vertical lines. What has likely happened to the cats?
The cats are not making any conscious choices about what they learned about the environment.
Habituation implies that the stimulus was presented multiple times, but was not there originally.
Selectively rearing an animal is very different from breeding.
The cats learned to adapt to their environment through experience-dependent plasticity
The figure above is called a Necker cube. Opposite sides are parallel, and the cube’s orientation is ambiguous, alternating between the front face being the lower left or the upper right. Which cognitive mechanism creates this illusion?
Selective attention is the ability to maintain attention while being presented with masking or interfering stimuli.
Joint attention is the focusing of attention on an object by two separate individuals.
Divided attention occurs when an individual must perform two tasks which require attention, simultaneously.
Directed attention allows attention to be focused sustainably on a single task, in this case a single orientation of the Necker cube.
What is the term for the process of creating electrical energy in response to light?
Transmission is the electrical activation of one neuron by another neuron.
Perception is conscious sensory experience of neural processing.
Processing is the neural transformation of multiple neural signals into a perception.
Transduction occurs whenever energy is transformed from one form to another; in this case, light energy is transformed to electrical energy by rods and cones.
Pilots need accurate night vision to see effectively both inside the cockpit and to scan the sky for other aircraft. Pilots are advised to “close one eye when using a light to preserve some degree of night vision”. Why is this?
Light adaptation happens when one moves from a dimly lit area to a brightly lit area.
Dark adaptation occurs when one moves from a brightly lit area to a dark area.
The cockpit at night is dimly lit.
In dimly lit situations, most of vision is perceived through the stimulation of rods.
Dark adaptation is lost very quickly because the pigment rhodopsin is bleached
Many senses can contribute to the sensation of vertigo. Which of these statements describes a sense that is NOT contributing to postural control?
Postural control helps maintain or restore the sense of balance during an activity. This control is multimodal and requires input from many different systems.
The vestibular system is most often associated with the sense of balance.
The proprioceptive and visual systems check the body’s state of balance. If either conflict with the state of balance described by the vestibular system, a person will feel vertigo.
Input from nociceptors, which help the body react to gravity.
Which of these is an attribute of the magnocellular pathway?
The magnocellular pathway specializes in sending information about movement since most retinal ganglion cells begin outside of the fovea.
The magnocellular pathway is specialized for object tracking, but has a low spatial resolution.
High temporal resolution
Marr’s stages of vision describes how a 2D image on the retina is transformed to a 3D object. Which of these is NOT one of Marr’s 4 stages of vision?
In the primal sketch stage, edges, and texture are identified and used to create a basic scene outline.
In the 2.5D sketch stage, surfaces and scenes are related to one another.
In the 3D object-centered description stage, the object is able to be recognized from any angle or visualized as a 3D map.
The Marr’s first stage of vision is called either the grey level description or the input image, not 1D sketch.
What forms the border between the middle and inner ear
The incus is the middle bone of the ossicles, in the middle ear.
The tympanic membrane forms the border between the outer and middle ear.
The pinnae is the outer ear structure that sticks out from the head.
The answer is the oval window
The tympanic reflex helps prevent damage from loud sounds. How does the tensor tympani work to protect one’s hearing?
It is not possible to adapt to loud sound. Over time intense vibration from loud sounds causes damage to hair cells and loss of hearing.
Strong vibrations in the ear could damage the hair cells, regardless of whether they are within the audible range.
The tensor tympani dampens loud sounds by tightening the tympanic membrane. This slows down transduction.
How do the ossicles help to amplify the sound that reaches the tympanic membrane?
The ossicles transfer vibration from the tympanic membrane to the oval window.
The tympanic membrane has a much larger area than the oval window.
By transferring vibration from a membrane of large area, the tympanic membrane, to a membrane of small area, the oval window.
Researchers showed participants a video of two objects that appeared to be moving toward one another at a 90 degree angle. More than 88% of the participants saw the objects pass each other and continue on their original course. In a second condition, participants were played a click sound when the objects appeared to be close together. This time 63% perceived the objects as bouncing off each other in opposite directions. What impact did sound have on visual perception?
Before the click was played, only 12% of the participants judged the objects to bounce off each other.
After the sound was perceived, 25% of the participants revised their visual perception of the interaction between the objects.
The input from the auditory system modulated visual perception.
Which of these is NOT a direction in auditory space? Loudness Azimuth Elevation Distance
Auditory space is defined as the area extending around the head in all directions that is used to perceive sound.
Elevation describes the relative height of the sound above or below a plane extending outward from between the ears.
The azimuth is the angle left or right from a symmetry line equidistant from the ears.
Loudness is a perception based on a sound’s frequency and sound pressure level, not a direction in auditory space.
The kinocilium attaches to a potassium channel in the hair bundle. What type of gate is the potassium channel? Mechanical gate Voltage gate Chemical gate Ligand gate
Movement of the hair cell in one direction opens an ion channel, while movement in the opposite direction closes the channel.
A voltage gate are most often activated by membrane depolarization.
Ligand-gated ion channels are activated when a ligand, or chemical messenger, binds to an allosteric binding site.
Kinocilia and kinocilial links help transduce sound and movement through mechanosensitive gated channels.
The correct answer is mechanical gate.
