Speech Perception - Essay Example

Speech perception In the running of day to day life one constant aspect that holds great significance in the way we interact is speech. Speech involves the emission of a series of sounds which have unique acoustic structure which is made up of audible qualities over time. The human auditory system receives the segmented streams of information contained in whatever has been spoken. On receipt of the acoustic speech signal, the individual relies on their acquired knowledge on linguistics and their ability to deduce the intended message from the speech, skills which one develops from infancy (Florian, 1994). Perception represents the manner in which this stream of audible information is heard, interpreted, understood and conceptualized. Depending on the intellectual capacity of the listener, a great deal of information can be gathered from some fleeting acoustic signals. One can be able to make a judgment on indexical and spatial aspects of the speaker such as their gender, age, physical location, emotional state and so on. The level of comprehensions derived from speech is different in adults and children. In a variety of studies to investigate the manner in which adults and four-year-olds make inferences, familiar and unfamiliar animals were used as stimuli and evidence was found to suggest that category membership and similarity of conceptual information play a major role. Children tend to use category membership without clear and detailed mention of the relevant categories in tasks of their inductive behavior. They use category membership information that is available for familiar categories even when the categories involved in the experiments are not revealed to them. They do not blindly follow the school of thought that all entities that have the same name also share the same properties. A further investigation indicated that when three and four-year olds are asked to make inferences on which items taste the same they tend to assume that they are being asked about kinds of foods and hence they take color to be the supreme feature that categorizes similar tasting items. However when asked to determine items that are of a similar type the children based their inferences on the shapes rather than colors of the items that is to say similar shaped objects are of the same type. Just like in children category membership information plays a big role when adults make inductive inferences. For example if speech consists of a group statements, consisting of premise statements and a final conclusion statement, adults will more convinced to agree with the conclusion inferred from the previous statements only if there is a marked similarity between the premise category and the conclusion category (Downing , Sternberg &Ross ,1985). However unlike the case in children, adults tend to draw from their own additional background knowledge in making inferences and not just acting on only what is presented to them in speech. In studies on attribute-based induction, one is able to judge how adults and children fared when it came to a shift in their conventional beliefs. It was found that adults were more flexible and were willing to shift their perceptions based on new findings. Presented with an account of how scientific research has disproved a previously held truth, adults took into account the provided information for natural-kind stimuli and categorized the item in the manner that the new discovery would allow. Children were more reluctant to change their perception given the new information. Different inferences were also made when adult and children were presented with a natural kind transformation whereby one type of animal was physically transformed to look like another animal (for example making a raccoon look like a skunk). Subjects were asked whether at the end of the operation the resulting animal was still raccoon or had become a skunk owing to its acquired appearance. Children said it was a skunk which implies that they make judgments based on superficial perceptual properties rather than on the original pre-transformation category membership. However when the transformations were seen to be more and more ontologically extreme (e.g transformation of a raccoon to a rock) the children chose to stick with the pre-transformation information. Adults and older children on the other hand overlooked the transformation and stuck with the pre-transformation information about the animal. Another aspect of speech and perception is the inferring of mental states (.reading minds). This comes naturally to human beings and it can be accurate or inaccurate and is a key component in the formation of an impression, causal explanation, and judgments of responsibility, praise, blame and social meaning (Andersen ,Lazowski &Donisi , 1986). Mental state inferences have been studied at length in many domains but models depicting how this actually happens are rather varied and fragmented. A variety of great minds in the field of social psychology have isolated different strategies that are used by perceivers to be able to sort f read the minds of those speaking to them. Perceivers basically inspect closely and thoroughly the outward behaviors of those addressing them, project their own mental states onto others and resort to looking out for stereotypes. According to developmental psychologists from the moment a child is born he or she seeks to keenly examine behaviors of those around him in an attempt to unearth hidden intentions. As children grow up, they become experts in meeting one another’s actions with scrutiny seeking to discover the intended goal behind every deed or behavior (Ames, 2004). While scrutinizing another’s actions they are also keenly comparing their behavior to a host of previous episodes of action all with the aim of trying to work out the unseen intentions of the person by instinct. The mental state inference that results is not usually devoid of errors. Whenever it seems to the perceiver that more than one meaning can be derived from a certain kind of behavior they resort to alternative strategies to come up with a mental state of the actor. In this case the perceiver relies on his or her own biased stereotypes to settle the meaning behind any ambiguous behaviors. When an inference is unattainable even through stereotyping, the perceiver adopts a strategy that assumes that other people’s intentions are identical to their own (projective impulse). Language plays an important role in the understanding of speech. Spoken language communication is a feature that distinguishes human from non-human species. Speech and language skills are an important part of a child’s cognitive and socio-emotional development. How we arrange words in ours native language facilitates speech perception. A sentence construction which is not grammatical tends to hinder our understanding of it and this affects speech perception. For many it is thought that speech is something that we hear, however studies show that speech has an effect on a variety of senses the brain sees speech as something that can be hear, seen and even felt. When someone is speaking to us we receive a lot of speech information from visual cues such as teeth movement, tongue and other non-mouth facial features. The visual information one gets from seeing a person speak changes the way they hear the sound. The McGurk Effect is an example of the integration of two senses in speech perception; hearing and seeing. It was introduced by Harry McGurk. This phenomenon is known to work even if a person knows about it i.e. even when a participant is made aware about it they still find that their senses are integrated. Studies have shown that this integration takes place very early in the speech process. As far as the brain is concerned visual information and auditory information are not separate; they are indistinguishable from one another. When in a noisy surrounding say a busy crowded street or in a packed bar it is normally difficult to figure out what a particular person in saying yet it can be done. The human ability to pick out a single voice from the noise of a crowded environment is called the cocktail party effect. A team of scientists performed experiments on patients undergoing brain surgery. The patients were known to have normal hearing and language skills. Subdural electrodes were implanted to the temporal lobe to detect populations of neurons and record neuron activity. After the surgery, they then made the patients listen to speech samples from multiple different voices. The patients were asked to identify the words uttered by particular speakers while their brain activity was monitored. Software was then used to reconstruct the brain’s activity and assessed the manner in which it varied when the patients were listening out for the different voices. It was discovered that the cortex seems to respond to a single voice at a time when one is concentrating on making it out, conveniently blocking out the rest of the acoustic environment. Performance of perception is dependent on the attended stimuli. Thresholds bring about the fact that our senses have limits. The absolute threshold is the smallest amount of stimulus you can just sense something about half the time (Pillow ,Hill & Stein 2000). Difference threshold or noticeable threshold represents the smallest amount of change needed in a stimulus before we notice the change ourselves. The difference threshold is measured using Weber’s law which states that the change needed to notice a difference between two stimuli is proportional to the original intensity of the stimulus. In other words the more intense the stimulus, the more it will need to change before one is able to notice the difference. References Andersen S., Lazowski L., Donisi M. (1986). Self-Knowledge: Inference, Perception and Articulation THE ROLE OF BIASED RECOLLECTIONS INSELF-INFERENCE PROCESSES. Carlifonia: University of California-Santa Barbara. Ames, D. R. (2004). Inside the Mind Reader’s Tool Kit: Projection and Stereotyping in Mental State Inference. New York: American Psychological Association. Downing J., Sternberg R., Ross H. (1985). Multicausal Inference: Evaluation of Evidence in Causally Complex Situations. NewYork: American Psychological Association. Florian, J. E. (1994). Stripes Do Not a Zebra Make, or Do They? Conceptual and Perceptual Information in Inductive Inference. New York: American Psychological Association. Pillow B.,Hill V., Stein C.(2000). Understanding Inference as a Source of Knowledge: Childrens Ability to Evaluate the Certainty of Deduction, Perception, and Guessing. New York: American Psychological Association. Read More