AffectiveTask

Basic affective task (rating of emotional pictures) that can be used to test neurophysiological equipment.

Description

The AffectiveTask is designed to assess affective event-related brain potentials (ERPs) using visual pictures that were highly distinct on arousal level/valence category ratings.

The task is simple and straight forward. There are 60 trials in total. In each trial, an affective stimulus (picture) is presented for 3.0 seconds and participants are asked to give the respective ratings of their emotion on two visual analogue scales - one for the level of arousal (Not intense - Intense) and one for level of valence (Positive - Negative).

Visual pictures are selected from the Nencki Affective Picture System (NAPS), which consists of 1,356 realistic, high-quality photographs (Marchewka, Zurawski, Jednoróg, & Grabowska, 2014).

Installation

Download and run the experiment in Python: source("https://github.com/neuropsychology/AffectiveTask/blob/master/Affective.py")

Packages needed:

• [neuropsydia] (pip install https://github.com/neuropsychology/Neuropsydia.py/zipball/master)
• numpy
• pandas
• random

How to run the task

Download the NAPS stimuli

To request for NAPS images for non-profit academic research purposes:https://lobi.nencki.gov.pl/research/8/

Marchewka, A., Zurawski, L., Jednoróg, K., & Grabowska, A. (2014). The Nencki Affective Picture System (NAPS): Introduction to a novel, standardized, wide-range, high-quality, realistic picture database. Behavior research methods, 46(2), 596-610.

After obtaining the NAPS pictures, you can copy the selected NAPS images to the AffectiveTask/stimuli folder, or change the path directly in the experiment script.

# Define the path where the images stimuli are stored
path = "./stimuli/"

Stimuli Selection

Currently, there are 60 NAPS images selected for the AffectiveTask. Please refer to the stimuli_list.csv.

All selected stimuli belong to the People/Faces Category. Half of them are categorized as Neutral and the other half as Negative. We selected Negative stimuli based on, in decreasing order of importance, ratings of high arousal, negative valence, and a high tendency to avoid. We selected Neutral stimuli based on a range of valence ratings representative of neutrality/ambivalence.

We have plotted the affective ratings of 60 selected stimuli; the ratings include valence (ranging from highly negative to highly positive), arousal (ranging from relaxed/unaroused to excited/aroused), and approach–avoidance (ranging from a tendency to avoid to a tendency to approach a stimulus).

Based on the original ratings of the stimuli, the two groups, Neutral and Negative, are distinctively different on the arousal and valence dimensions.

Data

• Download the .zip file from here
• Unzip and extract the folders within this file (named S1, ...) in the /data/ folder.