Perceptual Safety-Nets

We use interaural cues to locate acoustic stimuli, but this information isn’t always so clear. How might one disambiguate information presented within these “cones of confusion”? And why are we not always confused about a sound’s location?

As Blake points out, there are a few simple ways that we naturally resolve a sound’s location when the “cones of confusion” created by IID and ITD interfere. The first is head movement: moving your ears out of the cones of confusion and re-orienting them in respect to the sound source will allow IID, ITD, the pinnas, and other mechanisms to work.

There are other subconscious cues not involving the ears that allow us to locate sounds. One is context. One of the areas where IID and ITD become confused is distinguishing sounds from directly behind and directly ahead. If you sleep with your face toward your alarm clock, for example, your ears won’t be able to tell you if the alarm is ringing from in front or behind your head; but familiarity allows your brain to compensate and tell you that the alarm is, as usual, in front of your face.

Another cue is another sensory system: vision. Vision allows us to see our environment and possible sound sources, and match the sources with specific objects. Vision can even correct mislocalization of sounds by the ears, as sound waves may bounce off surfaces before reaching the ear while light from objects goes directly to our eyes. However, the strong influence of vision over hearing can sometimes confuse perception, as shown by the McGurk Effect.

Effective Communication: Cell Phones or AIM?

Helen Keller said, “Blindness cuts me off from things; deafness cuts me off from people.” What do you think about this statement?

In the introduction to his chapter on the ear and auditory system, Blake writes that “Hearing provides the basis for many forms of social communication, particularly speech. Without the ability to hear voices, an individual must struggle heroically to remain in touch with the flow of social discourse” (353). And as noted above, Helen Keller felt that hearing loss was more socially detrimental than vision loss. Why is the sound of speech key to social interaction, and why might it be more so than vision?

First of all, conversation has countless nuances that would disappear once translated into purely visual messages. Word choice would become more limited, inflection and tone and volume would disappear, only one voice could be “heard” at a time. Laughter would seem completely absurd. Anything said by someone out of one’s line of sight would be lost.

One could argue that sight can substitute for hearing. Sign language and visual messages can be used to communicate, and visual cues such as facial expression can provide context for a statement. However, imagine talking to someone in a completely flat tone – over AOL for example. Even when one gives in to the use of emoticons, it is often still hard to tell exactly what the other person feels, especially when those feelings are more complex. A telephone conversation is much easier to understand, where sight of the person is lost and communication depends solely on hearing each other’s voices.

The one example that I can think of in which visual communication expresses sentiment accurately is through stories or books. However, most of us aren’t prize novelists, and (I imagine) find it easier to connect to a person over the telephone than through a written letter.

Therefore, while deaf people may come to use vision resourcefully to communicate with others, I understand the social significance of hearing and sympathize with Keller’s loss of her own.

Gustation as a Social Influence

When I consider the purposes of smell and taste, I think mostly of their enhancement of daily events like eating and doing laundry; perhaps even their usefulness in detecting danger (smoke, toxins, etc.). But I wonder, do smell and taste have any social purposes?

Apparently humans can tell the gender of other humans through smell alone. We are also affected to some degree by pheromones. As already stated, smell and taste can heighten one’s enjoyment of food and drink. How different, then, would a date be with the loss of these senses?

Henkin reports that people with smell disorders show less sexual interest (Blake 501). Furthermore, odor adaptation occurs when people’s sensitivity to certain odors is lessened by exposure (Blake 523). May the presence of new odors or pheromones explain (a bit) why people in long-term relationships may be attracted to a possible new “mate”?

As far as gender differences are concerned, does the discrepancy in the abilities of women and men to identify certain odors affect their interactions? The basic data that women are better able to identify coconut and men aftershave doesn’t point to much besides a possible difference in our body product purchasing patterns.

Nose Conditioning

We talked about the commercialization of smell. How, if at all, do you think smell influences your buying behavior?

There is definitely a right smell for the right place and right time – and definitely a wrong one also. I usually love the smell of food during mealtimes: coffee, cinnamon, or hot butter in the mornings, for example. Normally, I’d love a carton of lo-mein or hot french fries, but if I go on a run the loop at a certain time in the afternoon, I’m likely to find the greasy saltiness of P.F. Chang’s or McDonald’s unwelcome as they funnel dinnertime aromas onto West End.

I think that that is a big reason why people have certain foods and smells that they absolutely hate and absolutely love, and why these preferences change with time. If you don’t particularly like raisins, for example, but you are ravenous and that’s all you have in the cupboard (typical college-student scenario…), you’re apt to find the raisins surprisingly tasty. Humans can be conditioned to certain smells and tastes just as they can be to certain behaviors.

For example, in the case of the raisins, their taste becomes re-associated with energy and fullness, so one is more likely to seek them out for sustenance. Thus I think that it is through chance and circumstance combined with conditioning that many of our personal and cultural preferences for smells and tastes are created.