stimSize

Experiments

Controls the displayed size of stimuli. For image trials it resizes the stim1..stimN images; for video trials it resizes the video; for word trials it sets the font size of the word stimuli.

Syntax

Put a percentage in the cell and every stimulus on the trial is scaled by it: 80% shows each stimulus at 80% of its natural size.

To size the stimuli individually, write one spec per stimulus separated by ;: the first applies to stim1, the second to stim2, and so on. A single spec applies to every stimulus slot.

On image and video trials a spec must take one of these forms exactly:

Form	Meaning
N%	scale natural width and height by N/100
N (single integer)	fixed width N px, height scaled proportionally
W H (two integers)	fixed width W px and height H px, aspect ratio not preserved
max W H	scale DOWN proportionally to fit inside a W x H box, only when natural width > W or natural height > H; never upscales
max W	scale DOWN proportionally when natural width > W; never upscales

On word trials the spec is a plain number, read as a percentage of the base font size (2em): 100 gives 2em, 50 gives 1em, 200 gives 4em.

Options

Value	Trial type	Effect
empty	any	natural size (images: their own size, adjusted to the participant’s screen); words: 2em font
integer N	word	font size (2*N/100)em on all word stimuli
W H	image/video	exact pixel width and height
max W H	image/video	proportional shrink-to-fit W x H
max W	image/video	proportional shrink when wider than W
N%	image/video	multiply natural dimensions by N/100
N	image/video	width N px, proportional height
anything else	image/video	not recognized, slot falls back to natural size
anything non-numeric, or 0	word	falls back to 2em

Units are implicit pixels. Suffixes like px and keywords (small, large, full) are NOT accepted and are ignored.

Defaults & missing values

When the column is absent or the cell is left blank, images render at their own size and words at the 2em base font size.

An empty stimulus slot stays empty whatever size you set: it is never given a size of its own.

Note

Sizes are adjusted to the participant’s screen and rounded, so the stimulus is not always exactly the number of pixels you wrote.

Works with

• stimPos and layout: the sizes you set here decide how much room each stimulus takes, so they drive both the automatic row layout and stimPos block layout.
• target and mask are NOT affected: they always display at their natural size, whatever stimSize says.
• Video: only the first spec is applied, and only when the cell is not empty.
• Audio: stimSize never applies to audio.
• Word trials: only the first spec is read, and it applies to all the word stimuli; per-stimulus word sizes are not supported. The target word does not take this font size.

Examples

type	stimFormat	stim1	stim2	stimSize
test	.jpg	face1	face2	max 400 400

Both images are shrunk proportionally so neither exceeds 400 x 400; smaller images stay natural size.

type	stimFormat	stim1	stim2	stim3	stimSize
test	.png	a	b	c	50%;100%;200 150

stim1 at half its natural size, stim2 natural, stim3 forced to exactly 200 x 150 px.

type	stimFormat	stim1	stim2	stimSize
test	word	APPLE	PEAR	150

Word trial: all word stimuli rendered at 3em (150% of the 2em base).

type	stimFormat	stim1	stimSize
test	.jpg	photo	80%

The overwhelmingly most common real-world form: a single N% scaling spec applied to every stimulus slot (80% alone accounts for the majority of all observed stimSize cells). Percentage scaling dominates real files; explicit pixel pairs (250 350) and max forms are rare.

Tips & gotchas

• max forms only ever shrink a stimulus, never enlarge it.
• On word trials, everything after the first ; spec is silently ignored.
• An invalid spec in a multi-spec list only disables sizing for that slot; the other slots are still sized.
• A spec of 0 on an image or video trial gives a width of 0, so nothing is visible; on a word trial 0 falls back to the 2em default.

Caution

On video trials a percentage spec is scaled to the participant’s screen twice, so 50% comes out smaller than half of the video’s natural size on most screens. Fixed forms (W H, N) are scaled once, as expected. Use a pixel size when the exact video size matters.