Categorization in Macaca fascicularis

Nama : Kanthi Arum Widyastuti G362070051
Pembimbing : Bambang Suryobroto Akichika Mikami Achmad Farajallah
Tanggal Lulus : 25 Januari 2012
Judul Disertasi : Categorization in Macaca fascicularis
  Kemampuan kategorisasi Macaca fascicularis
Ringkasan:
Kategorisasi adalah kemampuan seseorang untuk mengelompokkan individu-individu atau kejadian-kejadian ke dalam kelompok yang berbeda. Kemampuan kategorisasi didukung oleh konsep yang dibentuk di otak. Ada beberapa tingkat kategorisasi. Pada tingkat yang paling dasar, semua anggota kelompok memiliki banyak persamaan ciri fisik dibandingkan dengan kelompok lainnya. Semakin tinggi tingkat kategorisasi, persamaan ciri fisik di antara anggota kelompok semakin sedikit. Selain manusia, hewan diduga juga memiliki kemampuan kategorisasi. Salah satu contoh kategorisasi adalah diskriminasi spesies hewan yang berbeda. Penelitian ini bertujuan untuk mengetahui kemampuan diskriminasi spesies pada Macaca fascicularis. Monyet ini memiliki kemampuan untuk melihat foto sebagai representasi dari benda sebenarnya. Penelitian ini menggunakan stimulus berupa foto-foto wajah dari manusia dan hewan dengan metode matching-to-sample task. Saya melakukan tiga eksperimen utama. Pertama, saya ingin menguji apakah M. fascicularis dapat mengelompokkan manusia dan makaka ke dalam dua kelompok terpisah. Kedua, saya ingin mengetahui apakah monyet mampu membedakan antara individu-individu spesiesnya dengan individu-individu dari spesies lain. Terakhir, saya ingin menguji apakah monyet mampu membedakan antara manusia dan hewan lain non manusia. Hasil penelitian menunjukkan bahwa M. fascicularis mampu memisahkan dan mengelompokan objek-objek ke dalam kategori yang diujikan walaupun saya menyingkirkan informasi visual dari stimulus seperti warna dan bentuk. Kemampuan monyet untuk mengidentifikasi objek berdasarkan sedikitnya informasi fisik mengindikasikan adanya kemampuan dalam membentuk konsep yang lebih abstrak. Selain itu, pada eksperimen ke dua, monyet saya berhasil menemukan ciri-ciri unik dari masing-masing spesies makaka. Saya juga menemukan bahwa monyet berhasil mengelompokkan foto-foto hewan yang berbeda secara fisik ke dalam satu kelompok. Saya menduga bahwa monyet dapat membuat konsep yang lebih abstrak berdasarkan hubungan non-perseptual sebagai dasar untuk mengelompokkan objek ke dalam satu kategori. Saya menyimpulkan bahwa dalam mengkategori hewan, M. fascicularis menggunakan beberapa tingkatan abstraksi.

 

Summary:
Categorization is an ability to group individuals or events into different classes mediated by conceptualized mental image. There are several levels of categorization and within a taxonomy the levels are nested. At the most concrete level of categorization, all or most members of the category shared common physical attributes that differ from other category. The higher the level of category, the fewer common attributes between members of the group. In addition to humans, the ability to categorize has also been proposed in animals. In addition to humans, the ability to categorize has also been proposed for animals. Being able to identify, visually or otherwise, a new object as a member of a category is an advantage for animals. It should help them to distinguish between food or non-food, or to discriminate between species of animals. This species discrimination is important to prevent hybridization among species.

Using matching-to-sample task, present experiments tested the ability of the long-tailed macaque (Macaca fascicularis) in discriminating dichotomousstimuli of different animals. The species has been shown to be able to see photos as representations of real objects so we used facial photos of humans and animals for the stimuli. Using operant conditioning method, I trained monkeys to associate matching to sample stimuli against a distractor stimulus. First, I showed monkeys a sample stimulus as a reference to be matched. To ensure that the subjects paid attention to the sample stimulus, they had to touch it and for this they received reward that they find beneath the stimulus. Next, I presented a matching stimulus and a distractor stimulus side-by-side. The subjects must choose one of them. When the subjects chose the matching stimulus, they received a piece of food as a reward; the response was counted as a correct one. When they chose the distractor, they did not get any rewards. Subject’s motivation for reward warranted the choice of the matching stimulus. The location of matching and distractor stimuli on the tray was arranged pseudorandomly. I blocked every 20 trials into one session and measured their correct rate. If the subject chose the matching stimuli higher than 90% in a session, I interpreted they were able to associate matching to sample stimuli. Logically, this may be inferred as the subject had developed dichotomic concepts of matching against distractor. When they showed this competence, they went to test phase. I expect that monkeys were able to transfer their concept learned in training phase into new stimuli by showing the same performance in both baseline and test trials. In the test phases, I introduced new matching and distractor stimuli and see their response into the stimuli. I did three major experiment. First, I tested their ability to classify human and macaques into separate group. Second, I tested their ability to discriminate their conspecific from other macaques. And the last, I tested whether the subjects able to discriminate non-human animals from human.

In all of these experiments I found that the subjects showed high performance in categorizing objects, even when I discarded details of visual informations, such as color and local features. The ability to identify objects with reduced representation of physical properties means that the subjects are able to generalize attributes of members of the group. This would indicate that the subjects have ability to create a higher level abstraction. On the other hand, in discriminating intragenic macaque species, I found that they were able to extract uniqueness of each species. More over, I also found that the subjects able to put photos of non-primates animals that shared very few similarities in physical properties into one group. Monkeys may able to create a logical concept such as A and non-A. I suggest that the subjects could create abstract concepts free from the physical properties as a basis to put objects into one category. Thus, I conclude that M. fascicularis are able to perform multiple levels of categorizations.

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