presTime2

Experiments

Caution

Legacy column. It still works in old experiments, but do not use it in new ones. Use presTime instead: it accepts one presentation time per screen, separated by semicolons.

Caution

Legacy column. It still works in old experiments, but do not use it in new ones. Use presTime instead: it accepts one presentation time per screen, separated by semicolons.

presTime2 is a legacy column that overrides the presentation time of the second screen of a trial. It exists for old trial files that specified screen 1 and screen 2 times in separate columns. New trial files should put all per-screen times in presTime as a semicolon list; the column is kept only for legacy support.

Syntax

Put a single whole number of milliseconds in the cell: it becomes the presentation time of the trial’s second screen.

That is the only form this column accepts. The semicolon lists, min_max ranges, a|b|c alternatives and V*N repetitions of presTime do NOT work here.

Options

Value	Behavior
empty (or absent)	Ignored; presTimeS2 is used instead, and if that is empty too, no override happens.
integer N	The second screen’s presentation time becomes N ms, replacing whatever the second presTime value said.
non-numeric	The override is skipped.
N<garbage> (e.g. 500ms)	The leading number is used, so 500ms overrides with 500.

Defaults & missing values

Leave the cell empty, or leave the column out, and nothing is overridden: the second screen keeps the time presTime gave it.

When the cell is filled in, the override is applied before the trial works out whether the last screen should stay up until the participant responds. That ordering has a consequence worth knowing about: see Tips & gotchas.

Works with

• presTime: presTime2 replaces the second screen’s time only. Every other screen keeps its presTime value.
• presTimeS2: the same override under an older name. presTime2 wins when both cells are filled in, because presTimeS2 is only consulted when presTime2 is empty.
• ISI: the trial must actually have a second screen, otherwise the override is never used. On the legacy path that means at least one real ISI gap; a second screen can also come from a stimScreens grouping (next bullet).
• stimScreens: screens built from a valid stimScreens grouping (on trials without a target) are timed the same way, so presTime2 overrides the second screen’s time there too. When stimScreens is set and presTime is empty, every screen first gets the 1000 ms default, so presTime2 replaces that 1000 ms rather than leaving screen 1 untimed. On a two-screen stimScreens trial it also means the last screen hides after the presTime2 value instead of waiting for a response.
• target: with a target, the target has the first screen, so presTime2 times the first test-stimulus screen after it. Target trials always use the legacy ISI screen building, and stimScreens is ignored for them.

Examples

1. Legacy two-screen trial: prime 150 ms, probe 600 ms:

type	stimFormat	stim1	stim2	presTime	presTime2	ISI
test	.jpg	prime	probe	150	600	50

Equivalent modern form: presTime = 150;600.

2. Override the second value of a presTime list (the 400 is replaced by 900):

type	stimFormat	stim1	stim2	presTime	presTime2	ISI
test	.jpg	a	b	300;400	900	100

Tips & gotchas

• On a two-screen trial where presTime gives only one value, adding presTime2 takes away the “last screen waits for a response” behavior: both screens are now timed, so the second one hides after the presTime2 value.
• The override always applies to the second screen, however many screens the trial has. On a single-screen trial it does nothing at all, without warning.

Caution

presTime2 cannot stand in for a missing presTime on a trial whose screens come from ISI: with presTime empty, the first screen is left untimed and never gives way, so the second screen is never shown. Always give screen 1 a positive presTime. On a stimScreens trial this trap does not exist, because an empty presTime is filled with the 1000 ms default first.