The n-back task is a classical assessment of working memory capacity. Initially developed by Kirchner (1958), the task presents a continuous stream of stimuli, and the participant must identify when the same stimulus (or stimulus belonging to the same category) is presented n steps earlier in the sequence.
You will need to build a behavioural n-back task using PsychoPy that conforms to the requirements outlined below and allow you to measure reaction and accuracy for each condition.
Design
This again is a simple ‘flat’ design the number of experimental conditions you have can vary but you should have at least two:
- Low n – there should be a low number of steps between the identical stimuli.
- High n – there should be a high number of steps between the identical stimuli.
Experimental requirements
Your experiment must include the following
- An information and consent sheet.
- 30 trials in each condition.
- A practice block where feedback is given to the participants based on their performance.
- Feedback in practice trials should be – correct/incorrect/no-response, too slow.
Trial requirements
- The interval between trials (also known as the inter-trial-interval: ITI) should be filled with a fixation cross – the length of time the fixation trial is on the screen should vary such that it’s offset is unpredictable.
Use your imagination
There are several aspects of the experiment that you can change freely and systematically; this means that you will be able to test your own specific hypothesis. Here is a list of somethings you can change but it isn’t comprehensive; if it isn’t specified above – you can change it.
- Nature of the stimuli -> words, pictures, letters, symbols etc.
- What participants are trying to identify is ‘the same’ –> colour, meaning, location, look.
- Number of blocks and n’s -> you can have just low and high, or more intervals.