Multitasking
Part3
Read the text and answer the questions below.
Multitasking
A
Scientific research has identified a bottleneck in our brains that could suggest we are fundamentally incapable of true multitasking. If experimental findings reflect real world performance, people who think they are multitasking are probably just under performing in all of their parallel pursuits.
B
The problem, according to René Marois, a psychologist at Vanderbilt University in Tennessee, is that there’s a sticking point in the brain. In order to locate this, Marois asked volunteers to watch a screen and press a key with a specific finger when a particular image appeared. Then, in a separate activity, they learned to listen to different recordings and to respond by making a specific sound. In both tasks,typical response time was about half a second, and volunteers quickly reached their peak performance. The trouble came when Marois showed participants an image, then almost immediately played them a sound. It appeared that if the second task is introduced within the half-second or so it takes to process and read to the first, it will simply be delayed until the first one is done. Delays progressively shorten as the interval between presenting the tasks lengthens.
C
There are at least three points where we seem to get stuck, says Marois. The first is simply identifying what we’re looking at. This can take a few tenths of second, during which crucial window of concentration we are incapable of seeing and recognising a second item. This limitation is known as the attentional blink. A second limitation is our short-term visual memory. This capacity shortage is thought to explain, in part, our astonishing inability to detect even huge changes in scenes that are otherwise identical, so-called change blindness. A third limitation is that choosing a response also takes brainpower. Selecting a response to one stimulus will hold back by some tenths of a second your ability to respond to a parallel one. This is called the response selection bottleneck theory, first proposed in 1952, and elaborated on by Marois and his colleagues in 2006.
D
But David Meyer of the University of Michigan has other ideas. Known as something of an optimist by his peers, Meyer has written papers with titles like “Virtually perfect time-sharing in dual-task performance’. His experiments have show that with enough practice at least 200 tries-some people can execute two tasks simultaneously as competently as if they were doing them one after another. Not all people manage this harmonious time-share, however. Meyer argues that individual differences come down to variations in the character of the proceessor-some brains are just more ‘cautious’, some more ‘daring’. And contrary to popular belief, there are no noticeable difference between men and women. Meyer believes that it’s not a central bottleneck which causes dual-task ‘interference’ but rather adaptive executive control which ‘schedules task processes appropriately to obey instructions about their relative priorities and serial order’.
E
Marois’s volunteers have also shown a huge improvement at managing concurrent tasks through regular practice. Where he disagrees with Meyer is in what the brain is doing to achieve this. Marois speculates that practice might give us the chance to find less congested circuits to execute a task – like finding trusty back to avoid heavy traffic on main roads – effectively making our response to the task subconscious. But while some dual tasks benefit from practice, others simply do not according to Pierre Jolicoeur of the University of Montreal. Dual tasks involving visual stimulus and a motor response* (which he dubs ‘in the eye and out the hand”) and auditory stimulus with a verbal response (in the ear and out the mouth) can, with enough training, be performed as well together as apart. He speculates that the brain connections they use may be somehow special,because we learn to speak by hearing and learn to move by looking. But pair visual input with verbal response, or sound to motor, and there’s no such dramatic improvement.
F
For research purposes, these experiments have to be kept simple. Real-world multitasking poses much greater challenges. Needless to say, there appear no researchers who believe that you can safely drive and have a phone conversation. And according to results from a study at the University of Utah, even using a hands free phone does not improve a driver’s response time. The study confirms that what distracts a driver so badly is the very act of talking to someone who isn’t present in the car and therefore is unaware of the hazards facing the driver. And the general preconception that we tend to get worse at multitasking as we age is born out. In one study conducted by Art Kramer at the University of Illinois, for example, both young and old participants were asked to do a simulated driving task while carrying on a conversation. He found that while younger drivers tended to miss background changes, older drivers failed to notice things that were highly relevant as well, and likewise had more trouble paying attention to the more important parts of the scene.
G
However, Kramer also found that older people improved their performance with practice, and that brain scans showed that underlying that improvement was a change in the way their brains became active. While it’s clear that practice can often make a difference, the basic facts remain sobering. For most of our history, says Marois, we probably never needed to do more than one thing at a time so we haven’t evolved to be able to. “We have this impression of an almighty, complex brain,’ he says, ‘and yet we have very humbling and crippling limits. *motor response: a response that involves a muscular movement
Questions 27-31
Choose the correct answer.
Write the correct letter A, B, C or D in boxes 27-31 on your answer sheet.
27 The main purpose of René Marois’s experiment was to establish
whether some people are more capable of multitasking than others
the stage at which people become too overloaded with input to respond efficiently
whether a person can perform tasks simultaneously in different situations
the difference in a person’s reactions to visual and auditory stimuli
28 What does David Meyer say about dual-task performance?
Certain types of tasks are easier to carry out concurrently than others
Success rates vary according to the complexity of the responses required
Anybody can achieve dual-task competence if they repeat the exercise enough times
Success at dual-task activities depends on the person concerned
29 On what point do Marois and Meyer agree?
the role of the subconscious in interpreting dual-task stimuli
the reason underlying the delay in response to dual-task stimuli
the value of repetition in improving performance in dual-task situations
the cognitive process enabling us to perform dual tasks competently
30 According to Pierre Jolicoeur, the kind of dual tasks which can benefit from practice are those involving
combinations which mirror the way people acquire basic skills
procedures which form part of people’s everyday activities
a spoken response to a visual prompt
a motor response to an auditory stimulus
31 In his dual-task experiments, Art Kramer observed that,compared with younger participants, older people
performed better in some aspects of the study
found it harder to concentrate on key aspects of driving
were less able to respond to the conversational input
gained little from repeated practice of the tasks
Questions 32-35
Complete each sentence with the correct ending A-E.
Write the correct letter A-E in boxes 32-35 on your answer sheet
The phrase ‘attentional blink’ describes
32
Scientists talk about ‘change blindness’ to denote
33
The idea of the ‘response selection bottleneck’ was suggested as an explanation for
34
Meyer uses the term `adaptive executive control’ to refer to
35
A
the delay in deciding on an appropriate reaction to a stimulus.
B
variations between people in their ability to respond to dual-task situations.
C
the period when we are processing input and therefore unable to take in further information.
D
a mechanism which places tasks in sequence according to their perceived importance.
E
a failure to identify differences between similar images.
Questions 36-40
Do the following statements agree with the views of the writer in Reading Passage 3?
In boxes 36-40 on your answer sheet, write
36 In the scientific community, Meyer’s theories receive less support than those of Marois.
YES
NO
NOT GIVEN
37 It is commonly thought that gender plays a significant role in determining dual-task performance.
YES
NO
NOT GIVEN
38 Jolicoeur’s experiments on dual-task competence took placeunder laboratory conditions.
YES
NO
NOT GIVEN
39 Research into phone use while driving has produced some surprising results.
YES
NO
NOT GIVEN
40 Kramer’s initial findings about cognitive abilities and aging confirm popular assumptions.
YES
NO
NOT GIVEN
答案：
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