Resampling timeline sample size after every block

[j22tis]

Hi!

I'm trying to figure out, how to update the value of sample size for a block of trials. I have two kinds of blocks and I want their size (amount of trials in them) to be a randomly sampled number from [11,12,13,14,15] so that it would be resampled after every block.

In my current attempts, I managed to generate a random value for sampler, but it would be the same fixed value throughout the experiment:

generate amount of trials for block 1, by sampling randomly from 10:15

var size1 = jsPsych.randomization.sampleWithReplacement([10,11,12,13,14,15],1)[0];

generate amount of trials for block 2 by sampling randomly from 10:15

var size2 = jsPsych.randomization.sampleWithReplacement([10,11,12,13,14,15],1)[0];

define block 1

var easy_block = {
timeline: [experimental_trial],
timeline_variables: easy_params,
sample: {
type: 'with-replacement',
size: size1,
weights: [0.25,0.25,0.75,0.75],
}}

define block 2

var hard_block = {
timeline: [experimental_trial],
timeline_variables: hard_params,
sample: {
type: 'with-replacement',
size: size2,
weights: [0.25,0.25,0.75,0.75],
}}

combine blocks into timeline

var blocks = [hard_block, easy_block];
var experimental_timeline = jsPsych.randomization.repeat(blocks, 4)

add to final procedure

experimental_procedure = {
timeline: experimental_timeline,
};

How would I go about resampling the values for size1 and size2 after every block? :)

[jodeleeuw]

I don't think you can do this with the type: 'with-replacement' method but you could roll your own version by using the type: 'custom' method and then you can easily update the variables in between blocks. The function should run anew with each block/repetition.

https://www.jspsych.org/overview/timeline/#custom-sampling-function

[j22tis]

Thanks for the pointer!

I tried something like this:

var easy_params = [
{direction:"right", coherence:"0.4"},
{direction:"left", coherence:"0.4"},
{direction:"right", coherence:"0.8"},
{direction:"left", coherence:"0.8"}]

// hard block parameters (medium trial = 0.4, hard = 0.2 coherence)
var hard_params = [
{direction:"right", coherence:"0.4"},
{direction:"left",coherence:"0.4"},
{direction:"right",coherence:"0.2"},
{direction:"left",coherence:"0.2"}]

Define easy block
var easy_block = {
timeline: [experimental_trial],
timeline_variables: easy_params,
sample: {
type: "custom",
fn: function(t) {
var block_size = jsPsych.randomization.sampleWithReplacement([2,3,4],1)[0];
var t = jsPsych.randomization.sampleWithReplacement(t, block_size, [0.25,0.25,0.75,0.75]);
return t}
}}

Define hard block
var hard_block = {
timeline: [experimental_trial],
timeline_variables: hard_params,
sample: {
type: "custom",
fn: function(t) {
var block_size = jsPsych.randomization.sampleWithReplacement([2,3,4],1)[0];
var t = jsPsych.randomization.sampleWithReplacement(t, block_size, [0.25,0.25,0.75,0.75]);
return t
}
}}

Combine to procedure
var experimental_timeline = [hard_block, easy_block];

experimental_procedure = {
timeline: experimental_timeline,
repetitions: 4
};

And it seems to work judgig by the output data :) Does it seem reasonable?