Week 9 - Evaluating experimental research

Question 1

What are situational variables?

Answer 1

Situational variables refer to the specific combination of psychological and contextual factors that exist in a particular pain situation

Question 2

what are participant variables?

Answer 2

A participant variable is any characteristic or aspect of a participant’s background that could affect study results, even though it’s not the focus of an experiment

Question 3

What are some examples of situational variables?

Answer 3

• Sound
• Temperature
• Stimuli
• Life events
• Time of day
• Lighting
• Position of participant

Question 4

What are some examples of participant variables?

Answer 4

• Genetics
• Age range
• Profession
• Physical/cognitive characteristics
• Nationality
• Gender
• Conditions

Question 5

What are some perceptual considerations?

Answer 5

• Adjusting to lighting
• Viewing distance
• After image

Question 6

What are some environmental considerations?

Answer 6

• Noise control
• Temperature control
• lighting control
• Distraction control
• Stimuli presentation

Question 7

What are some experimental considerations?

Answer 7

• Number of trials
• Blocks and breaks
• Randomisation
• Fixation control
• Instructions

Question 8

What is an example of stimuli presentation?

Answer 8

Refresh rate

Question 9

What is refresh rate?

Answer 9

How many times per second the image on the monitor is renewed

Question 10

What is the impact of viewing distance?

Answer 10

The distance between the participant and the screen can impact the quality of the sensory information and thus, speed and accuracy with which we can identify items on the screen. Therefore, we want to keep the viewing distance the same and also the same for the duration of the experiment.

Question 11

What is the impact of visual angles?

Answer 11

fMRI has demonstrated that increasing the viewed target’s visual angle, increases the extent of the corresponding neural activity pattern in the visual cortex

Question 12

How is the visual field represented?

Answer 12

It is represented in our primary visual cortex producing retinotopic maps. These maps are slightly distorted with more neurons allocated to the fovea.

Question 13

How can we help account for visual angle?

Answer 13

Each trial could begin with the presentation of a central fixation cross against a grey background. Once a stable fixation was recorded within the 2 degrees of the cross, a sample array was presented consisting of 1,2,4,6 coloured squares.

Question 14

What impact does adjusting to lighting have?

Answer 14

Dark and light adaptation simply means getting accustomed to less or greater levels of environmental illumination

Question 15

What does the term dark adaptation mean?

Answer 15

It stands for the recovery of visual sensitivity following the cessation of intense illumination

Question 16

What is after image?

Answer 16

An image that continues to appear in the eyes after a period of exposure to the original image due to continued photochemical activity

Question 17

What is negative after image?

Answer 17

Retina is exposed to bright light and becomes light adapted only in the area the light fell. If you then look at a uniform background that area will look darker

Question 18

What is positive after image?

Answer 18

Retina is exposed to dark light and after you look away the brain continues the signal for 500 milliseconds. If you then look at a uniform background that area will look lighter

Question 19

What is perceptual persistence?

Answer 19

The longer the stimulus is displayed the more sensory evidence is accumulated impacting accuracy and speed. Therefore, to control timing we need to control after image using masks

Question 20

What does randomisation mean in independent groups?

Answer 20

Randomisation of people into groups

Question 21

What does randomisation mean in repeated measures?

Answer 21

Randomisation of the order of conditions

Question 22

In fixation control, what does eccentricity mean?

Answer 22

Effects have often been linked to the cortical magnification factor concept that accounts for the relationship between visual acuity and distance from the fovea

Question 23

How can you improve instructions?

Answer 23

Make them standardised

Question 24

What is the best practice when considering environment?

Answer 24

• Control noise and temperature
• Where possible have no windows and use constand and controllable light source situated in a location that will prevent glare on the screen
• Ensure the computer settings are set up to match your computer’s refresh rate and screen resolution
• Make sure you can adjust the chair and monitor to ensure your participants are looking at the centre of the screen.

Question 25

What is the best practice when considering perceptual considerations?

Answer 25

• Giver the participants time to adjust to the lighting.
• Considering using masks to have better control over the stimulus presentation times
• Use a chin rest to standardise viewing distance is appropriate

Question 26

What is best practice when considering experimental procedure?

Answer 26

• Consider the number of trials and blocks carefully
• Make sure the randomisation procedures fit the design
• The instructions should be constructed carefully and standardised
• Make sure you have included fixations to control where your participants are looking when presenting visual stimuli for short durations

Question 27

Remember about inclusion and exclusion criteria!

Answer 27

By carefully considering the criteria for who can or cannot take part in your experiment you can add further control.