Remote 2020 (

remote exp.png

A tool for remote, web-based experiments.

  • Stimuli and responses are transmitted over the web

  • Experimenter and participant are connected in real-time

  • No registration or server setup required


An integrated platform to teach experimental programming

  • Integrated debugging window helps students learn programming through experiments

  • “Classroom mode” with instructor screen visible on all students' screens


Our recently developed 'Pixel-grids' enable the capturing of appearance of stimuli created on different types of grids. Responses are collected on the same grids as the original stimuli (with different sizes), allowing a highly precise analysis of the results. Observers respond on the grid interface by selecting squares to match the appearance of a stimulus that is difficult to discern. The interface can be used simultaneously with stimulus presentation or after stimulus offset. The movie on the right shows a version of the Pixel-grid with a comparison stimulus where the appearance capture made on the grid is displayed in the same size as the presented stimulus. We currently use Pixel-grids to investigate the appearance of stimuli presented to the retina using adaptive optics in conjunction with scanning laser ophthalmoscopy (AOSLO). 

  • Gomes Tomaz, Â., Harmening, W. M., & Sayim, B. (2021). Appearance at threshold: How Snellen symbols look like

Multi-dimensional Method of Adjustment

We developed an interface that allows to adjust stimuli on multiple dimensions. The Multidimensional Method of Adjustment provides several degrees of freedom to capture stimulus appearance and to create shape metamers. We combine the method with eye tracking and gaze-contingent stimulus presentation to avoid eye movements to peripheral stimuli while allowing long presentation times and repeated observations. Our novel interface uses familiar touchpad gestures whereby subjects adjust the number, position, orientation, and length of segments to modify a probe until it matches target appearance. The movie shows an example of capturing a peripherally presented stimulus. Note that the observer could not fixate the stimulus presented on the right because of gaze-contingent presentation.

  • Sayim, B., Melnik, N., Yildirim, F. Z., & Coates, D. R. (2017). Creating peripheral shape metamers.

  • Coates, D. R., Yildirim, F. Z., Melnik, N., & Sayim, B. (2017). Deconstructing peripheral appearance.

Geometrically Restricted Image Descriptors (GRIDs)

The GRID method allows to capture shape appearance with more detail than in typical categorical response tasks. Stimuli in the GRID paradigm are shapes consisting of distinct line elements placed on a grid by connecting grid nodes (A). Each line is treated as a discrete target. Observers are asked to capture target appearance by placing lines on a freely viewed response grid (B).

Lines are defined as strokes connecting two nodes, segments as strokes connecting two adjacent nodes without passing through any other dot (C). High speed eyse tracking allows gaze-contingent presentation in the periphery.

  • Melnik, N., Coates, D. R., & Sayim, B. (2021). Geometrically Restricted Image Descriptors: A method to capture the appearance of shape. [open access]


Gaze-contingent Free Capture

In the Free Capture method, participants depict how a stimulus appears without any constraints. High-speed eye tracking and gaze-contingent stimulus presentation enable rigorous control of retinal location (the illustration on the right shows how the target is only presented when fixaintg the central dot). For example, we investigated peripheral crowding with Free Capture and characterised how crowding modulates stimulus appearance. We discovered the phenomenon of "redundancy masking" (see also publications) using Free Capture. Below is a demonstration of the method when the Rey–Osterrieth Complex Figure was presented with free viewing (left) and in the visual periphery (right). When presented in the periphery, the presentation was gaze-contingent.

  • Sayim, B., & Taylor, H. (2019). Letters lost: Capturing appearance in crowded peripheral vision reveals a new kind of masking. [download] [online]

  • Coates, D. R., Wagemans, J., & Sayim, B. (2017). Diagnosing the visual periphery: Using the Rey-Osterrieth Complex Figure test to evaluate peripheral visual function. [open access]