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Research
Washoe looking through a magazine |
All research at CHCI is non-invasive; the research either
does not disrupt the chimpanzees' lives or, should it be potentially
disruptive to the chimpanzees' daily activities, it is entirely
voluntary. If a research design proves to be upsetting to the chimpanzees,
the research is halted and revised to be less intrusive. Because
the nature of research involves contact with the chimpanzees, researchers
who work directly with the chimpanzees must be trained extensively.
We recognize that the presence of the researcher itself can
affect the chimpanzees' behavior. However, this is true of nearly
all
research. In some cases, the research can provide enrichment for
the chimpanzees, giving them opportunities to interact socially
with the researchers or to participate in a forage that they would
not otherwise have had.
Read more about the presentations
and theses that have developed
out of research at CHCI. Listen
to an NPR Radio interview where Dr.
Jensvold talks about the research.
The Recent Expressive Lexicon of a Cross-Fostered
Chimpanzee
Jason M. Wallin, Mary Lee Jensvold, Roger S. Fouts, Deborah
H. Fouts Via. Friends of Washoe Newsletter, 29(4),
5-7.
NOTE: Jason Wallin presented this as a poster at both the
Rocky Mountain Psychological Association meeting in April and
Central Washington University’s Symposium on University
Research and Creative Expression in May. The poster won an award
for Outstanding Graduate Student Poster at the CWU Symposium.
INTRODUCTION
Purpose
The present study describes the recent use of signs of American
Sign Language by Tatu, a 32-year-old female chimpanzee.
Tatu
Tatu was cross-fostered by Drs. Allen and Beatrix Gardner from
January 1976 until May 1981. In every way possible, Tatu was
raised as if she were a deaf human child. In this rich and engaging
environment, Tatu (and other cross-fosterlings: Washoe, Moja,
Pili, and Dar) acquired signs of American Sign Language (ASL)
in patterns that paralleled those of human children (Gardner
& Gardner, 1989; Gardner & Gardner, 1978; Gardner &
Gardner, 1994; Rimpau, Gardner, & Gardner, 1989; Van Cantfort,
Gardner, & Gardner, 1989).
Tatu continues to be an active conversational partner at the
Chimpanzee and Human Communication Institute (CHCI), where she
has lived since 1981.
Reliable Signs
For this study, we considered those signs for which Tatu is
reliable. For Tatu to be considered reliable for a sign, three
different observers on three independent occasions must have
seen her use the sign appropriately and without a preceding
human model. Then, observers must have recorded Tatu’s
use of the sign for 15 consecutive days (Gardner, Gardner, &
Nichols, 1989).
Procedure
When caregivers observed a sign on Tatu’s reliable list,
they recorded it on a daily checklist. Only the first observation
each day was recorded. Thus, these are records of sign types
(see below).
Each caregiver was required to have at least one quarter of
university-level training in ASL and must have demonstrated
reliability in identifying the signs of each chimpanzee.
Sign Types
A count of sign types records the number of different signs.
The phrase FLOWER THERE SMELL FLOWER, consists of three sign
types FLOWER, THERE, and SMELL.
The dataset for this study is a record of sign types used each
day. This does not allow for calculating the absolute frequency
of Tatu’s signing (as she may repeat the same sign type
many times each day), but does permit us to describe the lexical
categories and variety of Tatu’s signs.
Results
Tatu signed an average of 17 different sign types each
day during the past 8 years.
Over the study period, Tatu increased the number of sign
types she signed each day.
Day to day, Tatu showed considerable variety in the signs
she employed in conversation.
For this measure, we divided up the dataset into pairs of consecutive
days and examined the sign types that were either 1) common
to both days or 2) unique to one day or the other. Tatu was
not repeating herself day after day. Most of her sign types
are unique to one day or the other and for every pair of consecutive
days, Tatu used a different subset of her vocabulary on the
first day than on the second.
Tatu employed a variety of lexical categories in her signing.
Lexical Category Observed Frequency Ratio of sign types observed
to Tatu’s reliable sign types
Nouns 24,451 65/72 (90%)
Inanimate objects 19,197 29/35 (83%)
Edibles 4,764 29/29 (100%)
Animates 491 7/7 (100%)
Noun/verbs 6,984 16/17 (94%)
Modifiers 5,077 12/14 (86%)
Colors 3,478 4/4 (100%)
Qualities 1,570 4/4 (100%)
Possessives 17 2/2 (100%)
Materials 12 2/2 (100%)
Quantities 0 0/1 (0%)
Markers & Traits 4230 12/13 (92%)
Locatives 4290 5/7 (71%)
Verbs 2673 15/15 (100%)
Pronouns 1539 2/2 (100%)
Names 1462 11/14 (79%)
Generic 1077 3/3 (100%)
Chimpanzees 380 3/3 (100%)
Humans 4 4/8 (50%)
Tatu used 138 (90%) of the 154 reliable signs in her vocabulary
during the past 8 years. She used 50,686 sign types over the
2,922 days.
SMELL (2313) PAINT (209) GLOVE (4)
CRACKER (2034) POPCORN (195) NO (4)
BLACK (1859) ORANGE (184) OPEN (4)
MASK (1829) QUIET (166) PEN/WRITE (4)
ONION (1820) COME (149) BELT (2)
THAT (1750) FRIEND (149) BITE (2)
MILK (1556) GRASS (148) CATCH (2)
DRINK (1477) KISS (148) CUP (2)
YOU (1473) GIRL (131) LIGHT (2)
THERE (1429) PLEASE (106) PEACH (2)
RED (1411) LAUGH (97) BALL (1)
CHEESE (1404) SLEEP (96) BART H. (1)
BANANA (1366) MEDICINE (82) COMB (1)
GUM (1192) SWALLOW (82) DR. G (1)
HURRY (1191) PEA/BEAN (75) HANDKERCHIEF (1)
GO (1180) CAT (71) HOME (1)
GIMME (1161) ME (66) MARTI G. (1)
CARROT (1134) DOG (61) RIDE (1)
CEREAL (1116) CLEAN (59) ROCK (1)
MORE (1115) SHOE (58) SOUR (1)
POTATO (1068) BLOW (54) SUSAN N. (1)
PERSON (921) BRUSH (54) SWING (1)
APPLE (916) BABY (50) WHO (1)
FOOD/EAT/TASTE (888) KEY (49) WOOD (1)
ICE/COLD (837) GRAPES (48) YOURS (1)
OUT (762) DAR (46) ARLENE K. (0)
LIPSTICK (740) HOT (40) BATH (0)
CLOTHES (732) BUG (34) BIB (0)
SWEET (692) COW (34) DIAPER (0)
MEAT (570) CRY (30) DOWN (0)
GROOM (551) POTTY (30) GOODBYE (0)
FRUIT (536) WHITE (24) MARK L. (0)
TOOTHBRUSH (531) EARRING (22) METAL (0)
NUT (530) HAT (22) MRS. G (0)
FLOWER (508) CANDY (20) NAOMI R. (0)
RICE (501) BED (17) ONE (0)
COFFEE (495) DIRTY (17) STAMP (0)
BERRY (469) TICKLE (17) STRING (0)
OIL (440) MINE/MY (16) SWAB (0)
PLANT (407) SEE (15) UP (0)
IN/ENTER (348) CAR (14) VACUUM (0)
SANDWICH (343) HUG (14) WIPER (0)
TREE (324) CAN'T (12)
TEA (323) HORSE (12)
TATU (322) MOJA (12)
WATER (312) TIME (12)
BLANKET (296) GLASS (11)
CORN (291) HEAR/LISTEN (11)
SODAPOP (287) GARBAGE/CABBAGE (8)
COOKIE (285) SHIRT (8)
CHASE (283) TOOTHPASTE (8)
HURT (278) BOY (7)
SORRY (258) GLASSES (7)
BIRD (229) FINISH (6)
ICE CREAM (226) PEEKABOO (6)
GOOD (210) WRISTWATCH (5)
CONCLUSIONS
• Tatu uses a number of different sign types from several
different lexical categories in her daily conversations.
• Tatu changes the content of her conversations day-to-day.
• Tatu’s signing is increasing in both the daily
number of signs and the day-to-day variation in her signs.
FUTURE DIRECTIONS
• We plan to similarly describe Tatu’s signing from
the early 1980s to the present, and expand the study to include
Washoe, Moja, Dar, and Loulis.
• We can use this data as a baseline frequency of daily
sign types, to see if significant divergences appear as a function
of the day of the week, month of the year, periods around holidays
and significant events, etc.
REFERENCES
Gardner, B. T., & Gardner, R. A. (1994). Development of
phrases in the utterances of children and cross-fostered chimpanzees.
In R. A. Gardner, B. T. Gardner, A. B. Chiarelli, & F. X.
Plooij (Eds.), The ethological roots of culture. Dordrecht:
Kluwer Academic Publishers.
Gardner, B. T., Gardner, R. A., & Nichols, S. G. (1989).
The shapes and uses of signs in a cross-fostering laboratory.
In R. A. Gardner, B. T. Gardner, & T. E. Van Cantfort (Eds.).
Teaching sign language to chimpanzees. Albany, NY: SUNY Press.
Gardner, R. A., & Gardner, B. T. (1978). Comparative psychology
and language acquisition. Annals of the New York Academy of
Sciences, 209, 37-76.
Gardner, R.A., & Gardner, B.T. (1989). A cross-fostering
laboratory. In R.A. Gardner, B.T. Gardner & T.E. Van Cantfort
(Eds.), Teaching sign language to chimpanzees. Albany, NY: SUNY
Press.
Rimpau, J. B., Gardner, R. A., & Gardner, B. T. (1989).
Expression of person, place, and instrument in ASL utterances
of children and chimpanzees. In R. A. Gardner, B. T. Gardner,
& T. E. Van Cantfort (Eds.), Teaching sign language to chimpanzees.
Albany, NY: SUNY Press.
Van Cantfort, T. E., Gardner, B. T., & Gardner, R. A. (1989).
Developmental trends in relies to wh-questions by children and
chimpanzees. In R.A. Gardner, B.T. Gardner & T.E. Van Cantfort
(Eds.), Teaching sign language to chimpanzees. Albany, NY: SUNY
Press.
Social Structure in Three Captive Chimpanzees:
A Reexamination
by C. Austin Leeds, Maureen McCarthy, Jenny Morrison, Mary
Lee Jensvold, and Deborah Fouts. Friends of Washoe Newsletter,
31(1)11-12.
Introduction
The chimpanzees at the Chimpanzee and Human Communication Institute
(CHCI) have acquired American Sign Language and have lived in
a stable social group since 1980. Sanz, Driogk, Ketter, Pollick,
and Fouts (1996) evaluated the dominance hierarchy of the CHCI’s
five chimpanzees and their human caregivers, and found a stable
matriarchal hierarchy. Using live observations and video recording,
researchers evaluated verbal (signed) and non-verbal (behavioral)
interactions in two enrichment conditions. Washoe, the eldest
female of the group, was the alpha individual while Loulis,
her adopted son, was a high-ranking individual. Tatu and Dar
were middle-ranking individuals, and Moja and human caregivers
were low ranking.
Hayashida, Jensvold, Parker, and Fouts (2002) conducted a follow-up
study in which they evaluated the social structure of these
same five chimpanzees across 11 behavioral contexts. The hierarchy
remained stable from Sanz et al.’s study. The only major
change from 1996 to 2002 was that Tatu shifted from middle-
to high-ranking.
Since the 2002 study, the highest-ranking chimpanzee, Washoe,
and the lowest ranking chimpanzee, Moja, have passed away. In
2008, Leeds, McCarthy, Bismanovsky, Denton, Jensvold and Fouts
examined the social hierarchy of the three remaining chimpanzees
and found that there was no true highest or lowest ranking individual
and that the chimpanzees had a stable social structure of shared
dominance and cooperation. In the present study, researchers
examined the chimpanzees’ current social structure to
compare to the 2008 study.
Method
Participants
There were four subjects: three chimpanzees (Pan troglodytes)
and their human caregivers. The three chimpanzee participants
were Tatu, Loulis and Dar. Tatu and Dar were cross-fostered,
raised as if they were human children, while Loulis was raised
by his adoptive chimpanzee mother, Washoe (Gardner & Gardner,
1989). All of the chimpanzees have acquired American Sign Language
and live together at CHCI on the campus of Central Washington
University in Ellensburg, Washington. CHCI’s facility
consists of a 5,000 square foot outdoor enclosure, two 1,000
square foot indoor enclosures, and the Night Enclosure Area,
which consists of four interconnected rooms.
The human caregivers consisted of about 30 individuals working
at CHCI, ranging over several levels of training and involvement
in the day-to-day lives of the chimpanzees. Interactions between
the human caregivers and chimpanzees occurred routinely throughout
the day.
Although the chimpanzees have numerous caregivers, researchers
regarded all caregivers collectively as a single participant
because of the uniformity of low hierarchical rank across human
caregivers. The CHCI emphasizes an attitude of respect with
regard to human-chimpanzee interactions. Human caregivers regard
themselves as the lowest-ranking individuals in the hierarchy,
with all of the chimpanzees dominant to them. Caregiver interactions
with the chimpanzees thus reflect this attitude of respect.
Procedure
Summer apprentices collected data for this study. The Apprentice
Program at the CHCI provides an eight-week intensive care-giving
and research experience for students and professionals. Apprentices
learned to recognize and record each of the following: behavioral
contexts, the initiators and recipients in each interaction,
the beginning and ending times of each interaction, and whether
or not food was present.
Apprentices achieved > 85% inter-observer agreement on two
videotaped reliability tests and completed live data collection
training prior to beginning data collection. Data collection
took place for 30 days from July 6 to August 14, 2009. Data
collectors recorded dyadic interactions each day during ten
15-minute sessions in the Observation Area, where they observed
the chimpanzees in their daytime enclosures, and during a one
hour-long session in their night enclosures.
An interaction occurred when one individual directed behavior
toward another, including when an individual touched, peered
at, signed toward, or vocalized toward another individual, touched
an object another individual was holding, or exhibited other
communicative behaviors. Behavioral contexts were: access to
preferred resources, affinitive social, agonistic, discipline,
displacement, greeting, grooming, non-affinitive social, play,
reassurance, and threat. Dominance indices for each behavioral
context indicated which individual was dominant and subordinate
in each interaction. Researchers determined hierarchy by summing
the direction of interactions, placing each participant into
an ordinal rank within each context
Results
The results show that the dominance hierarchy of the chimpanzees,
based on the overall number of dominant interactions and excluding
the dominant human interactions, left Tatu and Loulis sharing
the top ordinal rank, with a dominance proportion of 0.4 and
Dar in the secondary ordinal rank with a dominance proportion
of 0.36. Loulis participated in 594 interactions, excluding
human interactions, and was dominant in 237 of them. Tatu participated
in 542 interactions, excluding human interactions, and was dominant
in 216. Dar participated in 543 interactions, excluding human
interactions, and was dominant in 195.
Excluding human interactions, Tatu was dominant in five behavioral
contexts: access to preferred resources, affinitive social,
displacement, non-affinitive social, and reassurance. Loulis
was dominant in three behavioral contexts: agonism, greet, and
threat. Dar was dominant in one behavioral context: play. Tatu
was ranked second in two contexts: agonism and play, while Loulis
was ranked second in four contexts: access to preferred resources,
affinitive social, displacement, and non-affinitive social.
Dar was also ranked second in four contexts: affinitive social,
greet, reassurance, and threat. Tatu and Loulis were both ranked
third in two contexts while Dar was ranked third in four.
Discussion
The primary purpose of this study was to establish whether the
chimpanzees had developed a defined hierarchy within their group
since the passing of Washoe, the previously highest-ranking
chimpanzee, and Moja, the previously lowest-ranking chimpanzee.
This study was also done to compare to the previous year’s
study investigating the same question. It was thought that since
hierarchy is such a complex social system, the time from Washoe’s
passing to the time of the previous study was not enough time
for the chimpanzees to establish a true linear hierarchy.
The results of this study corroborate the results of the 2008
study in that the chimpanzees have a shared and cooperative
social dominance structure. Though the ordinal ranks were calculated
for the chimpanzees, 0.4 for Tatu and Loulis and 0.36 for Dar,
the distribution of dominance within each context suggests that
utilizing a proportional ordinal rank is not enough to decisively
decipher dominance. Also, considering that previous studies
have shown that formulating linear hierarchies in small groups
is far from accurate (Appleby, 1983), it can be argued that
there is no true dominant and least dominant individual in the
group. Lastly, the spread of dominant interactions and contexts
was almost identical to the 2008 study, again showing a stable
and cooperative dominance hierarchy.
The data from this study shows how the chimpanzees can and do
continually adjust their dominance in different contexts, depending
on the current social comings and goings of the group. For example,
during the studies in which all five chimpanzees were present,
Dar was ranked fifth, and then in the 2008 study, Dar moved
to first. The rise from fifth to first was thought to have been
due to an agonistic encounter between Dar and Loulis that resulted
in numerous cuts and scrapes. Due to the chimpanzees’
tendencies to groom these cuts and scrapes after such encounters,
it was found that Loulis and Tatu spent more time than normal
grooming Dar because the social situation at the time required
it. In this study, Dar was ranked third in grooming. No agonistic
encounters like the previous studies were observed and thus
the situation did not require the grooming. This ability of
rank change due to social situations shows that the chimpanzees
truly have a cooperative and stable social dominance.
Some contexts have shown that certain individuals have remained
dominant in certain contexts over the last two studies. Tatu
has consistently ranked first in access to preferred resources,
displacement, non-affinitive social, and reassurance over the
last two studies, showing that Tatu may have established herself
as the dominant individual in these contexts, but allows dominance
in other context to be retained by the other members of the
group. Loulis has remained dominant in agonistic, greet, and
threat interactions over the last two studies. This shows that
the chimpanzees may have established certain roles within the
group, but have not taken these roles to a true dominant position
in the group.
The data collected in the present study show no significant
change from the previous year’s study, and in fact support
the previous year’s finding that the chimpanzees have
a stable and cooperative social hierarchy. The chimpanzees are
continually adjusting dominance in certain contexts depending
on the current social needs while also maintaining dominance
over certain contexts. These results show no trends to the formation
of a linear hierarchy, only to a cooperative social hierarchy.
References
Appleby, M.C. (1983). The probability of linearity in hierarchies.
AnimalBehaviour, 31, 600-608.
Gardner, R. A., Gardner, B. T., & Van Cantfort, T. E. (1989).
Teaching sign language to chimpanzees. New York: State University
of New York Press.
Hayashida, C., Jensvold, M. L., Grandia, A., Blake, S., Eburn,
C. A., Jung, C., Parker, S., Fouts, R. S. (2002). Social hierarchy
in five captive chimpanzees. Friends of Washoe, 23, 7-13.
McCarthy, et al. (2008). Social Structure of Three Chimpanzees.
Friends of Washoe, 30, 14-18.
Sanz, C. M., Droigk, J. A., Ketter, A. M., Pollick, A. S., Fouts,
R. S. (1996). Social hierarchy in two different enrichment conditions.
Friends of Washoe, 17, 10-15.
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