practicals

• what is reaction time?


  The time taken to respond to a stimulus.
• what are some factors that effect reaction time?

  age

  gender

  substance intake
• Ruler drop test


  -position ruler so the zero mark is between subjects thumb and forefinger (should be at same height each time to avoid variability)

  -experimenter holds ruler and drops at random time to initiate subjects reaction

  -subject catches ruler as swiftly as possible upon release

  -note reading on ruler where caught

  -further down ruler caught, slower reaction
• assessing the effects of stimulants or other factors


  have participant drink caffeinated beverage and repeat test after set period
• what are control variables for the ruler drop test?

  -arm used

  -height of drop

  -subjects prior use of substances (i.e. caffeine which could effect reaction time)
• what are computer based measurements?

  tests on computer that often involve responding to visual change by clicking mouse
• why are computer based measurements used?

  -more detailed view of subjects responses

  -remove potential human error in measurements

  -more reliable for repeat testing and tracking changes over time

  -remove inconsistencies such as anticipation
• what is the quadrats and transects practical used for?

  -measure population and distribution of species in a habitat
• what is distribution?

  how individuals of species are spatially arranged in particular area
• What is a quadrat?


  a square frame enclosing a known area
• what is the quadrat experiment used for?

  estimate population size of plant species in specific area
• quadrat experiment


  -divide area into a 1 meter by 1 meter grid and

  -use random number generator to pick number on grid

  -place quadrat on ground in location

  -count all specific plant species within quadrant

  -repeat this process several times

  -calculate mean number of organisms per quadrant
• how can you estimate the number of plant species in park by using quadrat experiment?

  -find mean number of plant species per meter squared

  -population = mean number of organisms per meter squared X total area of location
• percentage cover


  An estimate of the amount of ground in a quadrat covered by each species
• transect experiment


  -mark out a line in area of interest using a tape measure

  -collect data by counting all organisms along line

  -can use quadrant placed at intervals such as every 2 m alongside line
• why would you use a random number generator to determine coordinates?

  to avoid bias and obtain representative results
• what is random sampling?

  each sample has equal probability of being chosen
• what is systematic sampling?

  sampling technique where there is a fixed, periodic interval between consecutive samples