PsyCloud
Open Studio

Preview & Debugging

The Preview perspective runs your study against the same runtime participants will use — no publishing required. It's how you confirm trial logic, timing, and bindings actually work, and it's your main debugging tool.

The Preview perspective: scenario and display controls on the left, the live participant runtime showing the Stroop instructions, and an Events dock.
Preview before running. The participant runtime is live in the center; scenarios and display options are on the left.

Choose a scenario

Preview can drive the study with a simulated participant so you don't have to play through it by hand. Pick a Scenario in the left navigator:

  • Random participant — responds plausibly at random.
  • Perfect responder — always gives the correct response.
  • Timeout responder — never responds (exercises your timeout handling).
  • Custom scenario — define your own behavior.

Toggle Participant vs Debug mode, and pick a Display size (Desktop / Laptop / Tablet / Mobile) to preview different viewports.

Run it

  1. Start the preview

    Click Start preview. The runtime plays from the first phase — for the Stroop study it opens on the instructions screen, then runs trials according to the chosen scenario.

  2. Watch the events stream

    The Events dock fills with the runtime telemetry — trial starts, responses, checkpoints, block and experiment boundaries — each with a timestamp.

  3. Inspect any trial

    The Inspector shows the live Trial Context for the current trial: its phase, row index, resolved row parameters, the recorded response, and reaction time.

A completed preview run: 56 of 56 trials, the Events dock with 774 events, and the Inspector showing trial 56's resolved row params, response key, and RT.
After a full Random-participant run: 774 events captured, with the Inspector showing the resolved row params (congruency, color, word, correctResponse), the response key, and RT for the selected trial.

What the Inspector tells you

For the selected trial, Trial Context shows the resolved values — the actual data after bindings are evaluated, not the binding expressions. In the screenshot, trial 56 resolved to congruency = incongruent, color = green, word = blue, correctResponse = g, with a response of space at RT = 565 ms. This is the single most useful view for answering “why did this trial do that?”

The Jump to trial and Jump to Author source actions take you from a runtime event straight back to the design that produced it.

Debugging workflow

When a trial misbehaves: run a Perfect responder preview, select the offending trial in the Events dock, read its resolved Trial Context, then Jump to Author source to fix the binding or expression in Trial Design or Screen.

Sessions are local

Preview runs produce local sessions — they live in your browser, are visible here and in the local view of Monitor, and never touch a server. They're for debugging, not data collection. To gather real participant data you publish and host a run from Launch.

Next

Launch →

Validate, publish a version, host a run, and recruit participants.