Placebos – Is it all in the mind? – A comparison essay

Scientists have known for a long time that the mind plays a role in the process of medicinal treatment. They found that the psychosocial context of a treatment is central in the strength of the placebo effect, but the underlying neurological basis for this psychological phenomenon has only recently gained momentum in the field as a topic worthy of studying. This paper will discuss the experimental procedures and results of two independent experiments, and then examine how effective these experiments are in answering the broad question of “What factors create the placebo effect?”

In the first study, Benedetti et al. (2005) recruited 28 patients diagnosed with early stages of Alzheimer ’s disease (AD) and 16 healthy participants matched for sex and age as controls. Participants went into the lab for two blood tests on two consecutive days. In the open condition, participants were given lidocaine, a local anesthetic, applied at the location of the skin region where the needle was inserted. They were able to see the anesthetic applied, and they were told that the pain should subside in a few minutes. Participants in the hidden condition were not told they were given any lidocaine; the lidocaine was secretly applied on tape that was adhered to the punctured skin. They were not told that the pain was to subside. Participants in both conditions were then asked to rate their pain according to a numerical rating scale (NRS). The researchers recorded the participants’ electrocardiogram (ECG) and electroencephalogram (EEG) while they had their blood drawn. The conditions are switched the second day they go into the lab for a blood test. All participants then came back into the lab one year later and repeated all the procedures.

Continue reading

My Collection of Essays

I have folders and folders of academic work I have saved through my four years of studying at UC Berkeley. Now that I have graduated, I have a strong urge to just purge all of my work down the recycling bin on my desktop. But come on now! What a waste that would be! Hours and hours of hard work and sleepless nights were poured into the works of writing (whether BS-quality or better).

I think, I would like to share my words with the rest of the online community. A disclaimer is needed here: I am not a scholarly professional but merely a student just striving to learn and passing my classes. My essays are definitely not perfect; some are “A”-quality, others are “B+/B/B-” quality. Please do not copy and paste my words into your essay, you students, you. You may, however, cite me in your paper/project and message me to tell me what you’re writing about. Good academic practice facilitates discussion!

Viewing the Big Picture

The fusiform gyrus area, an area of the temporal lobe, specializes in face recognition. When looking at faces and other objects in which we are very familiar with, this area is highly active. Much research has been conducted in this area to understand how we are able to differentiate one face from another. How would I be able to recognize who is Bob and who is Paul?  Do I look at their entire face or the features on their face, e.g., their eyes or mouth?  There are currently two competing hypotheses: The holistic hypothesis is the view that the face is recognized as a whole rather than the internal features on the face, e.g., the eyes. It would be easier to recognize a part of the face when it is presented in the whole face relative to recognizing a part of the face by itself. The part-based hypothesis, on the other hand, suggests that face recognition relies on piecing together internal features of the face. Several studies have shown that face recognition rely on both the holistic process and the part-based process, but more so with the former. The focus of this paper is to present some research in support of the holistic hypothesis.

One landmark study was conducted by Tanaka and Farah (1993). They investigated whether subjects would be more accurate to identify parts of a face when it is presented in a whole face or in isolation. The entire study consisted of three separate experiments. In the first experiment, subjects had to learn and memorize the names of intact or scrambled faces. Before starting, subjects were placed in either the scrambled face or intact face condition. An intact face is not altered in any way. A scrambled face is one where the mouth is placed on the forehead and the nose is placed where the right eye would normally be. Subjects studied faces presented in block trials. After this learning phase, they went through the test phase where they were given a forced-choice recognition test of the faces they studied before. In the test, one face would be the original and the other would be a foil face, where a feature is switched with another feature from another face. Subjects were then given another forced-choice recognition test with only isolated parts. For example, given two noses, subjects were asked, “Which is Bob’s nose?” In experiment two, subjects underwent the same procedure of tests. Instead of scrambled faces, however, they studied faces inverted 180 degrees. The learning and test phases were the same. From these experiments, Tanaka and Farah found that subjects were more accurate in recognizing intact faces than scrambled faces and even less so for isolated face parts. These results are consistent with the interpretation that faces are stored holistically in memory rather than in terms of their parts. The last experiment used houses as stimuli to ensure the results from the first experiment was not because subjects were simply looking at upright stimuli. Subjects first served as the control group. They memorized human faces in the same procedure as before, and, consistent with previous results, subjects were better able to recognize faces when the whole-face was presented than when only isolated features were presented. Then they memorized the names and appearances of different houses, and took forced-choice recognition tests of isolated-parts and whole-objects. They did not show much difference in recognition accuracy when it came to houses. Whether features were shown in parts or as a part of a whole, subjects identified the house with similar accuracy across the different visual stimuli conditions. This finding supports their hypothesis that whole-recognition is used to a greater extent than part-recognition and that face recognition is different from the recognition of other objects, such as houses.

In another study, Tanaka and Sengco (1997) looked into the role of facial configuration in face recognition. It has been speculated that because the relation of everyone’s face features are the same, that is, the eyes are above the nose and the nose above the mouth, recognition of specific faces requires remembering the configural information (spatial distance between features) contained in the face.  Tanaka and Sengco reasoned that if one was to disrupt the configural information of a given face, this would greatly impair the retrieval of featural information. Their study included four experiments, each using upright faces, inverted faces, upright houses, or inverted houses as visual stimuli. Subjects in each respective experiment first memorized faces/houses and completed force-choice recognition tests, one for isolated parts and one for whole-face/house. The whole-face/house tests had subjects compare target items with foil items. Their percentage correct was measured. The manipulation, or independent variable, was the spacing between the eyes (Experiments 1 and 2) or the windows (Experiments 3 and 4). In the old configuration condition, spacing was not manipulated. In the new configuration condition, distance between the key features were manipulated, some close together and some far apart.

The results in this series of experiments showed subjects recognized features best when it was presented in the old configuration, moderately well with new configurations, and poorly with isolated parts. Interestingly, changes to facial configurations do not disrupt holistic processes in inverted faces or non-face objects. Configuration affected the holistic recognition of features on normal faces but had no effect on inverted faces or houses. This study showed that featural and configural information are intertwined in holistic face representations. When faces were intact and upright, subjects relied on configural information more than featural information. When presented with inverted faces or houses, subjects relied more on features specific to the object. Tanaka and Sengco thus concluded that configuration is an important factor in holistic recognition of faces.

Another group of researchers aimed to understand more about the interaction of the configural and part-based systems in face recognition. Rivest, Moscovitch and Black (2009) conducted various experiments on two subjects who had impairments on either object or face recognition and compared their results to those of healthy participants. Subject one, CK, has object agnosia (inability to recognize objects) and alexia (inability to understand written or printed language), but he has normal upright face recognition as long as there are sufficient configural information. Subject two, DC, has prosopagnosia (inability to recognize faces), whether it be based on configural or part-based processing, but he has normal object recognition. Rivest et al. had DC and CK perform a series of recognition tests. These tests included: recognizing inverted faces of famous people and inverted faces of cartoons, recognizing faces with their internal structures inverted, and recognizing disguised faces and faces with their external features inverted. Comparing the results of DC, CK, and healthy controls, the results led to the general conclusion that because there is a clear dissociation in CK between his part-based and configural face recognition and there is no evidence of this dissociation in DC, face recognition is greatly impaired when whole-face configurations are altered. CK was normal at recognizing upright whole faces, but when it came to distinguishing faces that were inverted, fractured or modified in such a way that altered the gestalt, he performed poorly on the tests. This study further supports the holistic representation hypothesis that face recognition relies more heavily on whole faces. Although configural face perception can proceed without part-based processing, the reverse is not true. Without using configural details of facial features (viewing the face in terms of all its parts), it is difficult for people with or without prosopagnosia to identify faces if all they have to rely on is facial parts.

Work by Schiltz and Rossion (2006) found more evidence that faces are represented holistically in the brain. They modeled their study to incorporate the composite face effect, which occurs when two identical parts of a face are perceived as being different if their respective bottom halves belong to different faces. Using functional magnetic resonance imaging, the research team scanned subjects’ brains while the subjects viewed images of faces, objects or scrambled faces to find where the brain was most activated when viewing these visual stimuli. The images were separated into top and bottom halves. In some conditions, the halves were aligned; in other conditions, the halves were misaligned.  When looking at aligned images of faces, the middle fusiform gyrus (MFG), which contains neurons most sensitive to whole facial stimuli, was most activated. There was a larger response in the MFG when faces were different from each other than when the faces were identical. This response is only larger when the top and bottom halves were aligned. When faces are misaligned, there is greater activation in the inferior occipital gyrus (IOG), the area more sensitive to facial features. If we were to remove a part of the face or scramble face features, this would cause marked reduction in neuronal response in the MFG area. This suggests that faces are represented holistically in the fusiform gyrus and occipital areas when we first see a new face and try to recognize it.

As the studies conducted by Tanaka and Farah (1993), Tanaka and Sengco (1997), Rivest et al. (2009), and Schiltz and Rossion (2006) show, there is good evidence that face recognition depends on holistic processing more than featural processing. It is generally agreed that faces are recognized not on the basis of their individual features, but in terms of the wholethat emerges from the features. These findings suggest that while the brain processes featural details and use it for face recognition, it relies more on a holistic approach to facial recognition.

References:

Rivest, J., Moscovitch, M. & Black, S. (2009). A comparative case study of face recognition: The contribution of configural and part-based recognition systems, and their interaction. Neuropsychologia, 47, 2798-2811.

Schiltz, Christine & Rossion, Bruno (2006). Faces are represented holistically in the human occipital-temporal cortex. NeuroImage, 32, 1385-1394.

Tanaka, J. W. & Farah, M. L. (1993). Parts and wholes in face recognition. The Quarterly Journal of Experimental Psychology, 2, 225-245.

Tanaka, J. W. & Sengco, J. A. (1997). Features and their configuration in face recognition. Memory & Cognition, 25, 583-592.

Moore Addresses Descartes

G.E. Moore famously laid out a straightforward proof for the skeptic, namely, that he has hands. Moore’s response to skepticism maintains that we can know of everyday propositions and hence know the denials of skeptical hypotheses. It appears that Moore looks beyond Descartes’ skepticism and does not explain how he knows he has hands in the first place. In this paper, I will reconstruct Moore’s proof using Nozick’s Tracking Theory in a way that will address Descartes.

I shall first begin by discussing what Descartes wants to be proven when it comes to external things in the world. In First Meditations, Descartes gave us reason to doubt there are external things in the world: our senses sometimes deceive us and we often dream of things that happen when we are awake. Because of this, we need to first be able to distinguish which mental state we are in before we can say there are external things in the world, such as hands.

With this in mind, we can see that Moore’s proof does not address Descartes’ skepticism and even seems dismissive towards Descartes’ points. There are two main weaknesses in Moore’s argument. The first weakness is that Moore does not explain how he knows he has hands. For all he knows, there may be a hologram-projecting machine that follows him everywhere so that every time Moore looks down on his arms, he sees two hands that, unbeknownst to him, are projected hologram hands. Even if we doubt this odd occurrence and given that Moore does have hands, the premises being true do not imply that Moore knows them. The second weakness is that Moore’s argument is circular by nature. In order to know that he has hands, Moore must first know there are external things. However, in his proof, Moore concludes that he can know external things exist as a consequent of his having hands. The skeptic’s objection is that he cannot know he has hands unless he first proves that there is an external world because the premise depends on this. These two weaknesses in Moore’s argument show that he does not adequately address Descartes’ skeptical points; Moore does not know he has hands nor has he proven he does.

Yet, Moore claims that his proof of an external world is a rigorous one. After all, Moore writes, “we all of us do constantly take proofs of this sort as absolutely conclusive proofs of certain conditions” (Moore 27). Proofs of “this sort” are frequently made for everyday propositions. To illustrate further with an example, Moore pointed out that when we prove there are misprints on a page, we simply take our fingers and point at them. If we take this kind of demonstration as sufficient proof, then surely, Moore’s proof that he has hands should be sufficient. Given a hypothetical situation where we were to agree with what Moore proposes to be a rigorous proof, we can infer that Moore is not dreaming when he is making his hand gestures nor is he dreaming when he points out the misprints. Given that we know many everyday propositions, we can deny skeptical hypotheses, such as us not knowing whether we are dreaming right now. Moore’s proof takes the following form, where ‘P’ is any everyday proposition that we say we know, and ‘¬SP’ stands for the denial of a skeptical hypothesis that is inconsistent with our everyday propositions:

a) K(p)

b) K(p à ¬SP)

Therefore,

c) K(¬SP)

Moore’s proof tells us that if we know the truth of everyday propositions, then we should also know that skeptical possibilities are false.

I will now turn to Nozick’s Tracking Theory of Knowledge and consider Moore’s argument from the perspective of this theory. Nozick proposed that in order for an agent to know that P, in addition to P being true and the agent believing that P, the agent’s belief in proposition P must be sensitive to the truth of P. That is, in the nearest possible world where P is false, the agent will not believe that P. Likewise, in the nearest possible world where P is true, the agent will believe that P.

Using Nozick’s Tracking Theory, we can see that being sensitive to the truth helps us keep tabs on our everyday propositions. Our everyday propositions are based on possible occurrences close to our actual world. We know skeptical hypotheses to go against our intuitions and are highly improbable. Going along this point, we can say that a skeptical world is probably unlikely and very far out in our universe of possible worlds. The beliefs we currently hold about everyday propositions are true in close possible worlds and safe from the world of the skeptic. If we are able to know everyday propositions, then we are able to rule out radical skeptical hypotheses as being true. As Nozick wrote, “Whether or not Q is true in P worlds that are still farther away from the actual world [e.g., skeptical worlds] is irrelevant to the truth of the subjunctive” (Nozick 256). As long as we are able to track our everyday propositions in our actual world and other close possible words, we can say that we know them.

Let’s now consider Moore’s proof of external things by reformatting it to one that would fit Nozick’s Tracking Theory. Our proposition P is “I have two hands.” We have an agent named Bob. P is certainly true. Bob believes that P. In the nearest possible world, if P were false (Bob lost his hands in a firework accident), would our agent believe that ¬P (Bob does not have hands)? The answer is yes, Bob would believe that he does not have hands because he knows this to be a fact. He experienced the accident and he knows that he did not undergo surgery for prosthetic hands. Now let’s consider, in the nearest possible world, if P were true, would our agent believe that P is true? The answer is yes, he would take this statement to be true. He has not experienced anything traumatic that cost him his hands. As such, we can say that our agent, Bob, is sensitive to the truth and has tracked his knowledge in close possible worlds.

When Moore raised his two hands up, he could be certain that he has hands because he has no reason not to think he has hands; he is sensitive to the truth in his proposition. Not only does Moore hold this belief to be true, he holds this true across a range of close-by possible worlds. Even when confronted with a skeptical hypothesis, e.g., “We do not know whether we are dreaming or not,” Moore was able to hold onto this proposition; he still knows that he has hands despite others telling him the contrary. The skeptic’s objection seems so far-fetched that this objection does not influence his knowledge of everyday propositions, such as one as obvious as having hands.

All in all, Moore’s proof of an external world may be better received by skeptics if it was to follow the format of Nozick’s Tracking Theory. With his theory, Moore would be able to test the falsity and truthfulness of a proposition and determine whether he was tracking this proposition as knowledge. This theory also helps explain how Moore is able to bypass Descartes’ skepticism – the skeptical world does not influence the belief one takes in a proposition because it is too far out in from actuality in the realm of possible worlds.