Habituation Flashcards
Why do animals carry out habituation
-Detecting and responding to stimuli in animals requires energy, so it is important that animals do not waste energy on non-threatening stimuli
-Animals need to conserve energy for processes that increase their survival chances
Examples of habituation
-Humans no longer noticing a new smell or sound after repeated exposure
-Wild animals losing their fear of humans after having consistent non harmful interactions
-Animals learning to not be alarmed by the presence of non predatory animals
What happens if the stimulus that the animal has become habituated to changes + example
-If the stimulus changes, the nervous system respons to the stimulus again e.g a low level noise slowly gets louder
Process of Habituation
-When habituation occurs, fewer calcium ions move into the pre synaptic neurone after the nerve impulse reaches the end of the axon membrane
-This results in less neurotransmitters being released, meaning the action potential is less likely to be generated
-Fewer neurotransmitters binding to the post synaptic neurone results in fewer sodium channels being opened
-Fewer sodium ions move into the axon and the inside of the axon remains negative
-Threshold potential is not reached
-If the threshold potenital is not reached a nerve impulse cannot be transmitted to the effector and the animal does not respond to the stimulus
How can habituation be studied
Habituation can be studied by measuring the change in animal’s responses to non threatening stimuli
-For example, snails often respond to stimuli by retreating into their shell and not emerging until the harmful stimulus is most likely gone
-As the snails become more habituated, the time for them to emerge from their shells decreases
Investigating habituation to stimuli in snails
1.Place a snail on a clean flat surface and give it time to emerge from its shell
-use the same surface throughout the experiment
-ensure the humidity stays the same as snails will withdraw in dry environments
2.Gently brush the head of the snail with a damp cottonbud
-the snail will most likely withdraw into its shell in response to the touch
3.Start the stopwatch and measure the time it takes for the snail to reemerge from the shell and fully extend its eye stalks again
4.Repeat steps 2-3 10 times, making sure to measure the time the snail takes to fully reemerge each time
-Ensure that the same soft object (damp cotton bud) is used to touch the same part of the snail each time
-Waiting for the eye stalks to fully extend makes sure the end point is always the same
5.Plot a graph of the number of touches against the ttime taken for the snails to fully re emerge from their shell
-The graph will be expected to show a gradual decrease of time taken to re emerge as the snails become habituated to the stimulus
Welfare considerations for snails
-Snails are living organims and should be placed in suitable living conditions that replicate their natural habitat after the experiment ends
-The snails should be handled with care at all times and should not be placed in excessively dry or hot environments
