Visual Statistical Learning - Turk-Browne

Script Author: Katja Borchert, Ph.D. (katjab@millisecond.com), Millisecond

Millisecond thanks Turk-Browne et al. for providing the original stimuli!

Last Modified: January 31, 2023 by K. Borchert (katjab@millisecond.com), Millisecond

Script Copyright © Millisecond Software, LLC

Background

The script "Visual Statistical Learning II" implements the procedure used by Turk-Browne et al (2005) to study the role of attention on the unprompted statistical learning of temporal relationships inherent in a visual presentation of shapes. Turk-Browne et al (2005) expand on research done by Fiser and Aslin (2002) (-> see Inquisit script "Visual Statistical Learning" that implements the procedure used by Fiser & Aslin).

For a more detailed description: Turk-Browne et al (2005). The automaticity of visual statistical learning. Journal of Experimental Psychology: General, 134, 552-564.

Duration

20 minutes

Description

Participants are shown a sequence of 624 shapes, one shape at a time (at a presentation rate of 400ms each with a posttrialduration of 200ms), that are either green or red. The participant's task is to 1. attend to only one of the colored shapes (green or red, counterbalanced) and 2. press the Spacebar whenever a shape in the attended color repeats itself, regardless of how many shapes of the other color may have been inbetween the repeating shapes. The order of the shapes is carefully assembled and contains a repeated number of 4 shape triplets in green and red.

In the Forced-Choice part of the experiment, the script pins the 4 familiar triplet pairs (ABC, DEF, GHI, JKL - from the sequence) for the attended and unattended color against 4 novel triplets (AEI, DHL, GKC, JBF, see Turk-Browne et al). These novel triplets are made up of shapes that have never directly followed each other during the sequence presentation. All shapes in the Forced-Choice task are presented in black.

Procedure

PART1 & PART 2:
24 shapes (originals from Turk-Browne et al)* are divided into 12 green and 12 red shapes
(assignment is randomly done for each participant).
The 12 shapes in each color are then divided into 4 triplets: ABC, DEF, GHI, JKL

PART I: Shape Sequence
There are 2 individual shape sequences of 312 items that
1. get assigned to either the red shapes or the green shapes (counterbalanced) and
2. get interweaved randomly (with one constraint: remaining streams shouldn't differ by more than 6 shapes)
for each participant.
The result is the observed stream of 624 shapes. Each shape is presented for 400ms with a
Stimulus Onset Asynchrony (SOA) of 600ms.

Each of those 2 individual sequences were constructed such that
1. all triplets are presented 24 times
2. 6 of those 24 triplet repetitions double the last letter (e.g. ABCC, DEFF etc)
-> 6 x 4 (# of triplets) = 24 extra letters,
3. no immediate repeats of triplets (e.g. ABCABC)
4. no repeat of triplet pairs (e.g. ABCDEFABCDEF)
(24 (#repetitions) x 4 (#of triplets) x 3 (#of letters/triplet) + 24 extra letters = 312 letters in a sequence)

Scoring of Responses:
If the participant hits the spacebar within 3000ms (default, see Turk-Browne et al) of the onset of a target
(=repeated shape in the attended color), the response is scored as a Hit. Any other responses outside of that
responsewindow are scored as a False Alarm. Should a new target appear during the 3000ms responsewindow
(and the participant has not responded to the first target), the responsewindow is updated for the new target
and a possible response counts towards the new target.

PART II: Forced-Choice
In the Forced-Choice part of the experiment, the script pins the 4 familiar triplet pairs
(ABC, DEF, GHI, JKL - from the sequence) for the attended and unattended color against 4 novel triplets
(AEI, DHL, GKC, JBF, see Turk-Browne et al).
These novel triplets are made up of shapes that had never directly followed each other
during the sequence presentation. All shapes in the Forced-Choice task are presented in black.

Participants get to view 2 sequences of 3 shapes each. Each shape is presented for default=400ms
in the middle of the screen with a break of 1s inbetween sequences. Participants are asked
to decide which one was the more familiar one (default TASK: press "1" for first, press "2" for second
-> change keys under values).
Each of the 16 triplet-pairings for the attended and unattended color is presented twice,
once with the familiar sequence being presented first and once with the familiar
sequence being presented second. The resulting 64 possible forced-choice tasks are selected at random.

Stimuli

Millisecond thanks Turk-Browne et al. for providing the original 24 stimuli in red, green, and black!
see section Editable Stimuli

Instructions

Instructions are not original to the task. They are provided by Millisecond
as htm/html pages and simple page elements and can be edited either by changing
the provided htm/html files or directly under Editable Instructions.
To edit htm/html-files: open the respective documents in simple Text Editors such as TextEdit (Mac)
or Notepad (Windows).

Summary Data

File Name: vsl_turkbrowne_summary*.iqdat

Data Fields

Raw Data

File Name: vsl_turkbrowne_raw*.iqdat

Data Fields

Parameters

The procedure can be adjusted by setting the following parameters.