Black Box IEEE 1284 Podręcznik Użytkownika Pobierz pdf (Strona 51)

The Black Box Toolkit Page 51 of 98

8.4.1. Tutorial 1: Examining the response time error caused by using a mouse for

response registration

In this tutorial we want to discover the response time error that is attributable to using an

unknown mouse as a response device. To do this we utilise a simple reaction time

paradigm run on the remote PC in which a subject has to respond to the appearance of a

visual stimulus as quickly as possible by clicking the left mouse button. The stimulus then

terminates and a black screen is displayed for 1000ms before the next stimulus is

displayed. If we simulate a response 300ms after the BBTK detects the image then we

would expect the response time recorded by the paradigm to be 300ms. In other words

0ms difference in terms of observed - expected.

To check timing, a standard opto-detector is plugged into line 3 of the BBTK and attached

mid screen of the remote PC using the adjustable strap. An active switch closure flying

lead is tacked to the left mouse button micro-switch. The other end of the lead is plugged

into line 7. This means we have a way of both detecting a stimulus and responding to it.

For more details of the physical setup please refer to the detailed case study in the next

section.

To define the sequence of response and trigger events, DSCAR is started in design mode.

The interface is divided into two main spreadsheet grids. The upper allows you to define a

“Bank of Simulated Responses”. These are reusable response events where any response

event can be called upon when needed. Up to 32,000 possible response events can be

defined. An event can consist of simulated activity on one or more digital out lines. This

could be an active switch closure, Tone Generation etc. The lower sheet allows you to

define the patterns of events you wish to detect before generating a simulated response

taken from your response bank. Both sheets can be saved independently and reused later.

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Black Box IEEE 1284 Podręcznik Użytkownika Strona 51