Triad tests - PowerPoint Presentation

Slide1

Triad tests

Collecting and making similarity dataSlide2

Background

The

triad

test: from

personal construct psychology and the repertory grid developed by

George Kelly

in 1955

.

Adopted

by

cognitive psychologists

and

anthropologists to measure similarities among pairs of objects

.

Informants respond to the same set of cues and data can be compared across individuals.

Kelly, G. A. 1955. The psychology of personal

constructs.New

York: Norton. Slide3

Triad tests

In a triad test, you show people three things and tell them

to:

“Choose

the one that doesn’t fit” or

“Choose the two that seem to go together best,” or

“Choose the two that are the same.”

The “things” can be photographs, dried plants, or 3 x 5 cards with names of people on them. Slide4

DOLPHIN MOOSE WHALE

SHARK DOLPHIN MOOSE

Dolphin is the odd item in triad 1 if people are thinking about size.

It’s moose if people are thinking land vs. sea.Slide5

People often ask “What do you mean by things being ‘the same’ or ‘fitting together’?”

Tell them that you are interested in what

they

think that means.

By doing this for all triples from a list of things or concepts, you can explore differences in cognition among individuals, and among cultures and subcultures. Slide6

First use in anthropology

Romney

and

D’Andrade

(1964) presented people with triads of American kinship terms and asked them to choose the term that was most

dissimilar

in each triad.

For the triad “father, son, nephew,” 67

% selected

“nephew” as the most different of the three items; 22% chose “father.”

Romney

, A. K., and R. G.

D’Andrade

, eds. 1964. Cognitive aspects of English kin terms. In Transcultural studies in cognition. American Anthropologist 66 (3, part 2, entire issue): 146–70Slide7

Ask people to explain their choices

For the triad “grandson, brother, father,” one informant said that a “grandson is most different because he is moved down further.”

There’s a lot of cultural wisdom in that statement. Slide8

Bilingualism and St. Lucian disease terms

Does cognition of disease terms vary with bilingual proficiency in St. Lucia?

52 bilingual English-Patois speakers and 10 monolingual Patois speakers

.

Here is the formula for calculating the number of triples in a set of

items:

With

9 disease terms, there are 84 possible triads.

Lieberman

, D., and W. W. Dressler. 1977. Bilingualism and cognition of St. Lucian disease terms.

Medical Anthropology

1:81–110. Slide9

For the bilingual informants:

Two

triad tests, a week apart, one in Patois and one in English.

They

also measured

how bilingual their informants were

.

For the monolingual informants”

The 10 monolingual Patois informants were simply given the triad test. Slide10

There are n(n-1)/2 pairs in a set of items

For 9 items, there are 9(8)/2=36 pairs of items

Count

the number of times that each of

the 36

possible pairs of terms was chosen as most alike

in the

84 triads.

Each term in a triad test appears n-1 times, and each pair appears n-2 times, so they divided the total by seven. Slide11

Triads as similarities

This produced a similarity coefficient, varying between 0.0 and 1.0, in increments of 0.14 (1/7) for each possible pair of disease terms.

The larger the coefficient for a pair of terms, the closer in meaning are the two terms. Slide12

They analyzed these data for English-dominant, Patois-dominant, and monolingual Patois speakers.

When Patois-dominant and English-dominant informants took the triad test in English, their cognitive models of similarities among diseases was similar. Slide13

When Patois-dominant speakers took the Patois-language triad test, however, their cognitive model was similar to that of monolingual Patois informants.Slide14

The take-away:

Patois-dominant bilinguals hold on to two psychological models about diseases and switch back and forth, depending on the language they are speaking.

English-dominant bilinguals

employ the same cognitive

model of disease terms, whichever language they speak. Slide15

BIBDs –

Balanced incomplete block designs

Typically, the terms for a triad test are generated by a free list.

Free lists of illnesses, ways to prevent pregnancy, advantages of breast-feeding, places to go on vacation, and so on easily produce 60 items or more.

Even

an abbreviated

list for a pile sort may be 30 items.Slide16

With just 9 terms, there are 84 stimuli in a triad test.

For 15 items, the number of decisions an informant has to make jumps to 455.

At 20 items, it’s a mind-numbing 1,140. Slide17

Burton and

Nerlove’s

solution

Balanced incomplete block designs take advantage of the fact that there is a lot of redundancy in a triad test.

For 4 items, there are 6 pairs. If you ask “Which of these two foods is more nutritious?” the informant sees each pair just once.

Burton

, M. L., and S. B.

Nerlove

. 1976. Balanced design for triad tests.

Social Science Research

5:247–67. Slide18

Recall that in a triad test informants see each triad

n(n–1)(n–2)/6 times

and each pair n–2=2 times.

With 84 triads for 9 items, each pair of items appears 7 times. Slide19

Redundancy and lambda designs

This redundancy lets us reduce the number of triads in a triads test.

If each pair appears once (a

lambda 1 design), then only 12 triads are needed.

If each pair appears twice (a lambda 2 design), then 24 triads are needed. Slide20

For a lambda 1 design, each pair of items in the similarity matrix gets a score of either 1 or 0.

For a lambda 2 design, each pair of items in the similarity matrix is 0, .5. or 1.Slide21

For 10 items, a lambda 2 design requires 30 triads; for 13 items, 52 triads; for 15 items, 70 triads; for 19 items, 114 triads; and for 25 items, 200 triads.

Here are the solutions from Burton and

Nerlove

for 9 and 10 items.Slide22
Slide23

BIBDs reduce accuracy

In a L1 design, each pair of items occurs in the context of just one other item.

For dog, parakeet, whale, many people pick whale, even though dog and parakeet are not that similar.

Thus the similarity between two items is defined by a single, third item. Slide24

Steps in making a triads test

1. Identify domain.

2. Do key informant

interviewing /free listing.

3. Select short list from the total list.

4. Choose a BIBD or use a complete triad test.

5. Make the triad tests using Anthropac (randomize to eliminate order effects).

6. Collect triad data.

7. Score the data and

unrandomize

if necessary

Instructions for data entry in the

Anthropac manual Slide25

Procedure in

Anthropac

Tell

Anthropac

the list of items you have.

Select a

design (e.g. L1, L2).

Tell it the number of informants you want to interview.Slide26

Anthropac

prints out a randomized triad test, one for each informant.

Randomizing the order in which the triads appear to informants eliminates order-effects.

Anthropac

unrandomizes

the data on import.Slide27

Plusses and minuses of triad tests

Triad tests are easy to create with

Anthropac

, easy to administer, and easy to score.

Use with relatively few items in a domain.

In literate societies, most people respond to 200 triads in <.5hr, but it’s boring.

Literate

informants easily handle L2 tests with 15 items and 70 triads.

People prefer—even like—to do pile sorts, but pile sorts have their own problems.