Wednesday, November 7, 2012

Zentall paper on imitation

    This week's blog is going to focus on an online chapter titled, "Imitation in Animals: Evidence, Function, and Mechanisms" by Tom Zentall and Chana Akins.  It is primarily a review article discussing various topics and research studies about imitation.  Imitation is a rather complex and advanced form of learning which can only be determined after simpler forms of learning mechanisms have been ruled out as the explanation for a behavior.
     Imitation is generally defined as any influence that an organism may have on another that results in a similarity of behavior or appearance between the two.  Therefore, imitation may be used as a defensive mechanism when the viceroy butterfly mimics the appearance of the monarch butterfly.  The viceroy is normally hunted and eaten, but the monarch butterfly is considered unpalatable, so the viceroy mimics the monarch butterfly in order to confuse predators.  Another form of imitation, that we actually talked about in our Psych 118 class, is that of the killdeer.  This species of birds builds their nest on the ground, and, therefore, have developed unique ways of protecting their eggs and growing chicks.  Whenever a predator approaches, the mother killdeer will try to distract predators by flying away from the nest, but acting as if its wing is broken and that it has difficulty flying away.  This serves as an enticing catch for predators, and will pull them away from the nest to chase the killdeer.  The killdeer is essentially putting its own life at risk, in order to save its children.  In this way, the female bird is mimicking the pattern of flight shown by a bird with a broken wing.  As we will see, imitation can take on many forms, involving defense mechanisms, as well as, food foraging.
     It is important to remember that all behaviors are done only when there is motivation to do so.  Research is being conducted as to whether the presence of a member of the same species (a conspecific) near a rat that is being tested, serves to facilitate or hurt the motivation of a behavior.  One test was done surrounding a bar-press demonstrator and an observer.  This type of test involves two rats in a box, where one is trained to demonstrate a behavior, and the other must observe.  The observer rat is tested to see if it has learned a behavior.  Whenever the demonstrator rat got fed as a reward for his behavior, the observers were also more likely to learn the specific association and press the bars more as well.  In typical research cases, food reward serves as a good incentive to motivate behavior or a type of shock avoidance.  Food is also used in typical Pavlovian, or classical conditioning tasks because it is an enticing US that participants want.  The chapter actually says that social learning may be more likely to occur under conditions of fear motivation because of its evolutionary value.  I would agree with this because even though food is essential to survival, someone's first priority in life is to protect themselves so that they will be able to reproduce and pass on genes, before they go after food.  By introducing this topic, the point I am trying to get at is that in order to determine that imitation is happening, one must control for motivational effects that would arise by the food reward (consequence) for the behavior of the demonstrator.
    Another process that must be ruled out in order to determine imitation is local enhancement or stimulus enhancement.  Local enhancement means that an observer is drawn to an area because some other individual, usually a member of their own species (conspecific) is in that area.  Local enhancement is something that must be controlled for if imitation is to be explained as the true learning process.  Local enhancement can be used to explain how birds of the great tit species learn how to peck through the top of a milk bottle to get to the milk.  If one bird is pecking at the top of a bottle, then other members of its species may learn to do the same behavior.  This may be considered observation in some instances, but it can also be explained by local enhancement.  Simply the fact that another bird is in the area and showing interest to the bottle, may cause other birds to be intrigued as well and try pecking or experimenting with the bottle to try and get it open.  In that way then, local enhancement may bring another bird closer to a bottle and then it may learn to get to the milk inside through trial-and-error.  To clarify this, let me give an example with humans that is more relatable.  Let's say you are naive to the idea of using a dimmer switch to dim the lights in a room, but you walk into a room and see that there is someone next to the light switch playing around with it.  Simply the fact that someone is by the light switch draws your attention to that area, and you walk over there as well.  When you get to the light switch you may end up pushing the button, pulling it, tapping it, until you finally realize you have to move the dial clockwise or counterclockwise to dim the lights.  This may be misconstrued as learning through observation, but if you broke it down into simpler elements, you may see that local enhancement was at play, as well as trial-and-error learning.  It is important not to confuse imitation with these simpler learning mechanisms.  
    If you have studied psychology in any form, then you must have encountered the example of Konrad Lorenz and the imprinting ducks.  Imprinting is a term used to describe learning that occurs rapidly at a particular stage in life, such as early in life (infancy).  The infamous study showed that ducks that had just hatched would "imprint" on the first moving stimulus that they encountered, during what was called a "critical period".  Upon hatching, these ducks would follow the object that they saw moving, their mother, and follow its movements, walking in a similar style and pace.  In nature it is beneficial for ducks to imprint their mother in order to be protected and learn from her, but experimenters have also made ducks imprint to a human, as well as a soccer ball.  The distinction must be made here that imprinting is a form of social learning, but is not true imitation, although it appears that the ducks are imitating their mother.  It may be a form of classical conditioning, with the reduction of fear serving as reinforcement.  If you watch a video on the ducks imprinting their mother, you will notice that the ducks walk just like the mother and follow her every movement. When the mother stops, however, the ducks may walk forward a little bit out of formation, thus exploring the area around them, but always in close proximity to the mother.  They are clearly fearful of their surroundings, because they never venture off too far alone, but they are reinforced for walking like the mother and staying close to her, because their fear is alleviated.
     The primary research done by Akins and Zentall focuses on training quail to learn how to acquire food by either pecking at a treadle or stepping on a treadle.  Imagine a quail inside a training box, there is a hole where food is delivered and a light that signals that food is coming.  Think of the treadle as a pedal or a lever which the quail can peck at or press down on, in order to turn on the light and deliver food.  Akins and Zentall discovered that in an experiment involving an observer and demonstrator, the quail would learn how to respond to the treadle with the same body part as their demonstrator.  For example if their demonstrator was pecking at a treadle, the quail would learn to peck as well; if the demonstrator was stepping on the treadle, the quail would step as well.  One explanation for this may be local enhancement, as it may be assumed that a quail may be drawn to a certain light (stimulus enhancement) or drawn to a demonstrator (local enhancement) and then may mess around with the manipulanda in the area until it figures out what it takes to deliver a reinforcement.  This learning was a form of imitation, however, that could not be explained by trial-and-error learning; the observers were imitating and copying the same behavior that their demonstrator was performing.  Behaviors never occur within a bubble, as there are multiple factors at play leading up to a behavior.  First of all, it is important that food is actually delivered as a reinforcement for pecking or stepping on the treadle.  This is essential for the observer to establish the contingency between performing a behavior and the expected reward outcome.  If the observer does not see a food reinforcement arrive, then it will have no motivation to learn a behavior itself.  In this way, reinforcement may be serving as the catalyst to bring about imitation.  Akins and Zentall also found that hungry quail were more likely to imitate a demonstrator's behavior if they observed while hungry, than while satiated. To further prove that imitation was taking place, Zentall showed an example of deferred imitation.  Critics of this type of research have said that if imitation is happening immediately after the observer watches a demonstrator, then it may just be a reflexive response that is genetically predisposed and doesn't involve much cognition.  To disprove this idea, Zentall conducted his experiment with hungry quail and allowed them to observe either the treadle pecking or stepping.  He then tested these quail with a half-hour delay and saw that the quail were able to imitate the demonstrator's behavior, thus they had learned the behavior and had cognitively processed the learning, as opposed to simply performing a reflex.
     We must not think that imitative learning is the ultimate end on an evolutionary scale.  In other words, it is not an inevitability that species living in social groups will develop such behaviors.  Trial and error learning is a very necessary way to acquire new traits, especially in order to have the flexibility to figure out what is good to eat or not and adapt to a changing environment.  For example, pandas like to eat bamboo, but if their forests are depleted or destroyed, then imitative learning may not help them discover new sources of food, but rather trial and error learning will.  Think of imitation as a quick and efficient way of distributing a learned practice to observers, but will not necessarily help species discover new methods of food foraging.  Trial and error may lead to success in terms of flexibility, but it also has negative consequences if it leads to food poisoning, or in terms of practicality, it may be a time-consuming and inefficient practice that does not work in all situations.  The reasons I say these things is because imitation is found in apes and humans, as well as parrots and dolphins, but is not found in monkeys and some bird species, although they live socially in groups.  From a biological perspective, ultimately, whichever strategy that leads to greater fitness, in terms of being able to successfully reproduce and have multiple progeny will be passed on to subsequent generations.  Imitation is not always the behavior leading to that success.  
      Imitation can be explained in terms of psychological and biological mechanisms.  Psychologically, imitation may simply be a form of instrumental learning.  A clear-cut example stems from verbal behavior and imitation.  An eager and excited family that repeatedly says "daddy" around a baby, may eventually get the child to imitate that behavior and say "dadda" or "daddy", simply because it is being reinforced for that behavior through food and attention. This explanation may work for individual cases, but not all imitation is clear associative learning.  The alternative explanation for such behaviors is an inborn, genetic drive.  Experiments are being conducted on whether newborns can actually imitate, because this would rule out any cognitive explanation and align more closely with a biological explanation.  There is data that suggests that infants have an innate ability to observe and analyze the behaviors and movements around them, and match them up with their own movements in space, which would suggest an innate ability to imitate those around them.  This is clearly an interesting finding that could require some more time and investigation.  It is only in the context of both psychological and biological mechanisms that we may understand true imitation.  But as mentioned before, true imitation is a higher level of learning that must be distinguished from simpler forms of learning and enhancement.

Zentall, T., & Akins, C. (n.d.). Imitation in Animals: Evidence, Function, and Mechanisms.  In Avian 
          Visual Cognition. Retrieved from

No comments:

Post a Comment