Physiology, responses, respiration (PAG): Organism level systems: Biology: GCSE (9:1)

Reaction time

The amount of time taken to respond to a specific stimulus

How to measure reaction time

Catch a dropped ruler from a specific height, record the length caught in metres and then convert this into reaction time in seconds

Conversion table

A table that uses a formula to convert the distance of a caught ruler into reaction time in seconds

Metre ruler

The object that is held vertically above a participant's hand before it is dropped and caught

Dependent variable

The variable that is measured which is the reaction time in seconds for this experiment

Independent variable

The variable that is changed which could be the person tested, the presence of blindfolds or caffeine consumption

Control variables

The variables that are kept the same such as starting height, the person dropping the ruler, lighting and background noise

Effect of practice

The person catching the ruler may find it easier each time due to more experience which can be difficult to control

Caffeinated and decaffeinated drinks

Conducting a blind trial using unlabelled drinks that may or may not be caffeinated can account for the placebo effect

Placebo effect

A participant may have certain bias expectations during an investigation that may cause them to perform differently

Blind trial

A trial where participants are unaware of whether or not they have received a genuine treatment or a placebo

Placebo

A fake treatment or condition used in an investigation to determine the validity of an experiment

Posture

It is important for participants to keep their body and arm in the same position for each test

Dominant arm

The arm used for most activities, the same arm should be used for each test unless it is the independent variable

Mean average

The total sum of the data values divided by the number of times the data was recorded

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