Welcome to our Gorilla Open Materials page for our zebra stripe salience project. On this page you'll find the online image viewing/mouse tracking task we used as the basis for two experiments. In these tasks, participants viewing single images of zebra and are asked to click on the part of the zebra that catches their attention. Zebra images are presented with dichromatic colour adjustment, different simulated acuity levels, different sizes and with/without motion blur to simulated naturalistic viewing conditions for predators.
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This experiment tested how zebra species/subspecies and motion blur influenced salience estimates using the image viewing/mouse tracking task (listed above). The stimuli for this experiment began as forty-eight photographic images of single zebra against naturalistic backgrounds, comprising of twelve images of each of the following: plains zebra (no shadow stripes), plains zebra (shadow stripes), Grévy's zebra and mountain zebra.
The images were drawn from online photograph repositories (credit original authors) and were selected to show an unobstructed view of the zebra in profile.
These were colour-adjusted to simulate lion dichromatic vision and motion-blurred, non-blurred, left-facing and right-facing versions of each image were created, resulting in a final set of 196 stimuli. Participants responded by making a single mouse click on the part of each image that caught their attention.
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This experiment extended Experiment 1 using the same basic format and stimuli. In this experiment, the original 48 images were scaled down to produce two smaller sets of images simulating viewing at middle and far distances.
The images were drawn from online photograph repositories (credit original authors) and were selected to show an unobstructed view of the zebra in profile.
All images were adjusted to simulate three different visual acuity levels to simulate the photopic acuity of lions, an average of the mesopic acuity of lions and photopic acuity of hyaenas, and the mesopic acuity of hyaenas. All images were colour adjusted as for Experiment 1. For each species/subspecies, at each acuity level and image size, half of the images were randomly selected to be flipped horizontally for one group of participants and the other half for a second group of participants, resulting in a counterbalanced and equal number of left- and right-facing zebra for each group of participants. This resulted in a final set of 288 stimuli, at two sizes and three acuity levels. Participants responded by making a single mouse click on the part of each image that caught their attention.
Fully open! Access by URL and searchable from the Open Materials search page
