# Creating a four alternative forced choice task

**URL:** https://discourse.psychopy.org/t/creating-a-four-alternative-forced-choice-task/3126
**Category:** Builder
**Created:** [September 27, 2017, 3:01pm UTC](https://discourse.psychopy.org/t/creating-a-four-alternative-forced-choice-task/3126 "2017-09-27T15:01:36Z")
**Posts on this page:** 1
**Showing post:** 6

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### Author: ![Lyam\_Bailey](https://avatars.discourse-cdn.com/v4/letter/l/e79b87/32.png) [@Lyam\_Bailey](https://discourse.psychopy.org/u/Lyam_Bailey)
#### Post date: [October 17, 2017, 4:52pm UTC](https://discourse.psychopy.org/t/creating-a-four-alternative-forced-choice-task/3126/6 "2017-10-17T16:52:24Z")

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Dear Michael,

Apologies for the late reply. Thank you for your advice! I implemented the code you suggested. It seems to partially work as expected…but the experiment intermittently crashes and throws the following error:

corrAns = responses[indices[0]]  
IndexError: list index out of range

Do you know what might be going wrong…?

Thanks again,  
Lyam

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