Final answer:
Nonhuman primates involved in long-term language instruction have successfully displayed linguistic attributes such as focal vocabulary and phonology, productivity and displacement, and code-switching and symbolism.
Step-by-step explanation:
The linguistic attributes that nonhuman primates involved in long-term language instruction have successfully displayed are focal vocabulary and phonology, productivity and displacement, and code-switching and symbolism.
Nonhuman primates such as chimpanzees, gorillas, bonobos, and orangutans have been taught to use gestures or tokens to refer to things in their environment. They can combine these signs in a rule-based way to make comments and requests, demonstrating their ability to use focal vocabulary and phonology.
These primates have also shown the ability to generate new meanings and create new utterances, indicating their capacity for productivity and displacement. They can use simple words and word combinations to obtain what they want, suggesting their proficiency in these linguistic attributes.
Furthermore, some studies have observed nonhuman primates engaging in code-switching and symbolism, using symbolic systems in cooperative interactions to achieve goals. This ability to switch between different linguistic codes and use symbols demonstrates their capability in this attribute.