PSY 369: Psycholinguistics

Language Comprehension:Methods for sentence comprehension

Other Relevant Findings? Bias towards “well-formed” stimuli

Misidentify words with uncommon spelling patterns BOUT as BOAT misidentify nonwords (e.g., SALID) as words that are like it

(SALAD). Difficulty identifying nonwords with irregular spelling patterns

(e.g., ITPR) more than those with regular spelling patterns (e.g., PIRT).

Sublexical units bigger than phonemes and graphemes?

onsets and rimes onset: initial consonant or consonant cluster in a word or

syllable rime: following vowel and consonants

if words broken at onset-rime boundary, resulting letter clusters more easily recognized as belonging together than if broken at other points

example: FL OST ANK TR

vs. FLA ST NK TRO

Sublexical units

Adding a bigram level

By adding a frequency-sensitive bigram level, we can accountfor the findings of well-formedness along with the others.

Summing up

Word recognition is based on a feature-detector system Biased to perceive common or recently occurring

features

Studying Word Identification Generally people ask: what makes word

identification easy or difficult? The assumption:

Time spent identifying a word can be a measure of difficulty

Measures of identification time are usually indirect

Some Identification Time Measures Measure how long people take to say a string of

letters is (or is not) a word (lexical decision) Measure how long people take to categorise a word

(“apple” is a fruit) Measure how long people take to start saying a word

(naming or pronunciation time) Measure how long people actually spend looking at a

word when READING Line by line reading Word by word reading using eye movement monitoring techniques

Line-by-line

A banker is a fellow

Line-by-line

who lends you his umbrella

Line-by-line

when the sun is shining

Line-by-line

but wants it back

Line-by-line

the minute it begins to rain.

Line-by-line Problem:

Overall reading time for entire sentence or phrase

need for more “on-line” measurements Timing on a smaller scope

See effects at level of word

Word-by-word RSVP (rapid serial visual presentation)

Word-by-word

A

Word-by-word

lie

Word-by-word

can

Word-by-word

travel

Word-by-word

halfway

Word-by-word

around

Word-by-word

the

Word-by-word

world

Word-by-word

while

Word-by-word

the

Word-by-word

truth

Word-by-word

is

Word-by-word

putting

Word-by-word

on

Word-by-word

its

Word-by-word

shoes.

Word-by-word Moving window

Word-by-word

I xxxx xxxxx xxx xx xxxxxxxxx xxxxxxxxx xxxx xx xxxxxxxxx.

Word-by-word

x have xxxx xxx xx xxxxxxxxx xxxxxxxxx xxxx xx xxxxxxxxx.

Word-by-word

x xxxx never xxx xx xxxxxxxxx xxxxxxxxx xxxx xx xxxxxxxxx.

Word-by-word

x xxxx xxxxx let xx xxxxxxxxx xxxxxxxxx xxxx xx xxxxxxxxx.

Word-by-word

x xxxx xxxxx xxx my xxxxxxxxx xxxxxxxxx xxxx xx xxxxxxxxx.

Word-by-word

x xxxx xxxxx xxx xx schooling xxxxxxxxx xxxx xx xxxxxxxxx.

Word-by-word

x xxxx xxxxx xxx xx xxxxxxxxx interfere xxxx xx xxxxxxxxx.

Word-by-word

x xxxx xxxxx xxx xx xxxxxxxxx xxxxxxxxx with xx xxxxxxxxx.

Word-by-word

x xxxx xxxxx xxx xx xxxxxxxxx xxxxxxxxx xxxx my xxxxxxxxx.

Word-by-word

x xxxx xxxxx xxx xx xxxxxxxxx xxxxxxxxx xxxx xx education.

Word-by-word A couple of methods

RSVP (rapid serial visual presentation) Moving window

Better, more “on-line” But, these measures are also a little bit

unnatural (especially RSVP) e.g., Don’t allow regressions (looking back)

Eye-movements

Clothes make the man. Naked people have little or no influence on society.

Eye-movements

Clothes make the man. Naked people have little or no influence on society.

Eye-movements

Clothes make the man. Naked people have little or no influence on society.

Eye-movements

Clothes make the man. Naked people have little or no influence on society.

Eye-movements

Clothes make the man. Naked people have little or no influence on society.

Eye-movements

Clothes make the man. Naked people have little or no influence on society.

Eye-movements

Clothes make the man. Naked people have little or no influence on society.

Eye-movements

Clothes make the man. Naked people have little or no influence on society.

Eye-movements

Clothes make the man. Naked people have little or no influence on society.

Eye Movements Limitations of the visual field

130 degrees vertically 180 degrees horizontally

Clothes make the man. Naked people have little or no influence on society.

Retinal Sampling

Retinal Sampling

Eye Movements Within the visual field, eye movements serve

two major functions Fixation – Position target objects of interest on the

fovea Tracking – Keep fixated objects on the fovea

despite movements of the object or head

Eye movements Fixations Movements

Saccades Smooth Pursuit

Fixations The eye is (almost) still – perceptions are

gathered during fixations The most important of eye “movements”

90% of the time the eye is fixated duration: 150ms - 600ms

Consists of a series of small eye movements (tremor, drift, microsaccades)

Saccades Saccades are used to move the fovea

to the next object/region of interest. Connect fixations Duration 10ms - 120ms

Very fast (up to 700 degrees/second) No visual perception during saccades

Vision is suppressed

Saccades

Saccades

Saccades

Saccades

Saccades Saccades are used to move the fovea to the

next object/region of interest. Connect fixations Duration 10ms - 120ms

Very fast (up to 700 degrees/second) No visual perception during saccades

Vision is suppressed Ballistic movements (pre-programmed) About 150,000 saccades per day

Smooth Pursuit

Smooth movement of the eyes for visually tracking a moving object

Cannot be performed in static scenes (fixation/saccade behavior instead)

Smooth Pursuit versus Saccades

Saccades Jerky No correction Up to 900

degrees/sec Background is not

blurred (saccadic suppression)

Smooth pursuit Smooth and

continuous Constantly corrected

by visual feedback Up to 100 degrees/sec Background is blurred

Purkinje Eye Tracker Laser is aimed at the eye. Laser light is reflected by cornea

and lens Pattern of reflected light is

received by an array of light-sensitive elements.

Very precise Also measures pupil

accomodation No head movements

Measuring Eye Movements

Measuring Eye MovementsVideo-Based Systems

Infrared camera directed at eye Image processing hardware determines pupil position and size (and possibly

corneal reflection) Good spatial precision (0.5 degrees) for head-mounted systems Good temporal resolution (up to 500 Hz) possible