Quiñones et al. EARLY VISUAL PROCESSING AND PERCEPTION PROCESSES IN OBJECT DISCRIMINATION LEARNING

Published: 04-01-2021| Version 1 | DOI: 10.17632/ctz4vgk9d7.1
Contributor:
Maria Aylwin

Description

This data consiste of two files: 1. DiscriminationPractice that contains the d prime values from two groups of participants across 6 sessions of same/different discrimination practice. Brief (100 ms presentation time) and long (1000 ms presentation time) 2. Evaluation that contains the responses of two groups of participants in the evaluation sessions: memory (OLD/NEW task) and perceptual(SAME/DIFFERENT task).

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Steps to reproduce

Stimuli: black and white scrambled checkerboard-like patterns (10 x10 squares, 60 exemplars) 50% black squares (1.5 x 1.5 visual degrees) on a black background at the center of a 23 inch monitor. Practice. Participants performed six SAME/DIFFERENT practice sessions. Trials began with a fixation dot (1.5 to 2.0 s), then a sequence of two stimuli S1 and S2, lasting either 0.1 s for brief (B) or 1 s for long (L) stimuli (stim). A perceptual mask (M, an exemplar different from S1 and S2), was presented between S1 and S2 for 0.1 s or 1 s for B and L stim, respectively. Stim and masks were followed by a noise image (high frequency scrambled image from each stim, 0.4 s for S1 and M and 5 s for S2) A fixation dot was shown during the ISI (1.1 s for B or 0.2 s for L stim) between the noise and M and S2. The time between the onset of S1 and M and between M and S2 was 1.6 s. S2 was rotated clockwise or counter-clockwise by 90 degrees in a pseudo-random manner. Participants began each trial by pressing a button. After the second stim (S2), they responded if the stim pair (S1-S2) was “same” or “different” by pressing either the left or right buttons. Six stim lists (a random sequence of same and different pairs ) out of 30 checkerboard-like exemplars with an equal frequency of each exemplar as S1, S2 and M and a 50/50 ratio of same and different pairs. The sensitivity was quantified using the signal detection theory. We obtained the discrimination index (d prime, d') or sensitivity assuming the differencing strategy, using the Palamedes toolbox (AL_SDT_1AFCsameDiff_DiffMod_PHFtoDP routine www.palamedestoolbox.org). Evaluation: The perception group completed four evaluation sessions and the memory group completed three evaluation sessions. Perception. Participants performed a SAME/DIFFERENT task. The stim were the same set of 30 checkerboards from the practice sessions. Four stim lists of 120 trials each, divided in three blocks of 40 trials. For each participant, the order of the lists was randomly selected. Duration of S1 and S2 and M was 0.3 s. Stim and masks were followed by a noise image (0.4 s) for S1 and M and 5 s for S2 and the time between S1 and M; and M and S2 was 1.6 s. Participants responded after the onset of S2 by selecting one of six options (same very sure, same sure, same unsure, different unsure, different sure and different very sure). Memory. Participants performed an OLD/NEW task, stim duration (0.3 s). Stim were 30 checkerboards from the practice sessions (old) and 30 checkerboards not included in the practice sessions (new). Three stim lists of 120 trials, each a random sequence of 15 old and 15 new exemplars, divided in three blocks of 40 trials. Trials began with a fixation dot of a variable duration (1.0 to 1.5 s), followed by the stimuli (S, 0.3 s) and a noise mask. Participants responded after the onset of S by selecting one of six options (old very sure, old sure, old unsure, new unsure, new sure and new very sure).