Moray

Cherry’s (1953) method of ‘shadowing’ one of two messages for his study of attention in listening. Participants were required to repeat one of the two messages as they were listening to them.

•  The two messages were always presented simultaneously, either played to both ears at the same time (binaural task), or one to each ear (dichotic task).
•   He found that in binaural presentation it was very difficult to separate the messages, however, in dichotic presentation, not only could the participant separate the messages very effectively, but they were also almost entirely unaware of the content of the rejected (unattended) messages

In response to this research various other studies have investigated how such selective blocking of information could occur.

 Peripheral blocks (producing rejection of the message at a structure in the ear, such as the cochlea, or in early processing in the brain, at the cochlea nucleus) were suggested (Galambos, 1955), however, as these could only prevent responses in a limited way, such as blocking information from one ear, such explanations were unlikely to account for blocking or accepting particular types of stimuli.

Moray was interested in what kinds of stimuli and situations might lead to this, observing that mothers hear children crying and that a person at a cocktail party can respond when they hear their own name mentioned in another conversation.

Cherry has found participants who shadowed one task could recall nothing of the content of the 'rejected' task. They could however distinguish between speech, noise and tones, could recognise clicks and obvious changes in pitch, like changing from a male to a female.

The aim of the study is to test Cherry's dichotic listening findings in relation to:

• The amount of information recognised in the rejected message

• The effect of hearing one's own name in the unattended message

• The effect of instructions to identify a specific target in the rejected message

Research methods:

All tasks were laboratory-based, had high levels of control and had an IV and DV - THEREFORE ALL LAB EXPERIMENTS.

Sample:

Participant numbers are not given for experiment 1 but

12 participants took part in the experimental conditions in expeirment 2 

 Two groups of 14 were in experiment 3.

In all tasks, the apparatus used was a  BRENELL MARK IV STEREOPHONIC TAPE RECORDER MODIFIED WITH TWO AMPLIFIERS to give two independent outputs through attenuators, one output going to each of the earpieces of a pair of headphones

Matching for loudness was approximate, by asking participants to say when two messages that seemed equally loud to the experimenter were sujectively equal to them (to within +/- 1db)

The loudness of each message was approximately 60db above the participant’s hearing threshold, and the speech rate approximately 150 words a minute. All passages were recorded by one male speaker.

Repeated measures The IVs were a dichotic listening test and a recognition test, while the DV was the number of words recognised correctly in the rejected message.

In experiment 1 a short list of simple words was repeatedly presented to one of the participant’s ears whilst they shadowed a prose message presented to the other ear (the list faded in and out); the list was repeated 35 times. The participant was then asked to recall the content of the rejected message. About 30 seconds later they were given a recognition test using similar material, present in neither the list nor the passage, as a control.

Results: Experiment 1 - The mean number of words recognised (out of 7):Shadowed message- 4.9, Rejected message- 1.9, Similar words from either - 2.6.

There was no trace of material from the rejected message being recognised. The 30-second delay was unlikely to have caused forgetting, because words from early in the shadowed message were recognised.

When we direct our attention to a message from one ear and reject a message from the other ear, almost none of the verbal content of the rejected message is able to get through this block. 

independent measures design, for which the IV was whether or not instructions were prefixed by the participant’s own name, while the DV was the number of affective instructions.

Experiment 2 was conducted to find out the limits of the efficiency of the attentional block. Participants shadowed ten short passages of light fiction. They were told that their responses would be recorded and they should try to and make as few mistakes as possible. Rejected messages were played in the other ear which were not attended to, Moray wanted to find out of these messages would be heard if it included their name. The order of presentation of the rejected messages was as follows (instructions at the start of the passage/ instruction within the passage): 1 Listen to your right ear/ All right, you may stop now. 2 Listen to your right ear/ No instructions. 3 Listen to your right ear/ John Smith, you may stop now. 4 Listen to your right ear/ No instructions. 5 Listen to your right ear/Change to your other ear. 6 Listen to your right ear/ No instruction. 7 Listen to your right ear/ John Smith, change to you other ear. 8 Listen to your right ear - you will receive instructions to change ears/Change to your other ear. 9 Listen to your right ear/ No instructions. 10 Listen to your right ear - you will receive instructions to change ears/ John Smith, change to you other ear. The passages were read in a steady monotone voice at about 130 words per minute and participants’ responses were tape-recorded and later analysed.

Experiment 2 - Most participants ignored the instructions that were presented in the passages they were shadowing and thought this was an attempt to distract them. In the Affective (instructions preceded by name) condition 20 out of 39 messages were heard, while in the Non-Affective (instructions not preceded by name) condition only 4 out of 36 messages were heard. (3 results were rejected as participants started paying attention to the rejected messages). The results were highly significant.

independent measures design and the IVs were whether digits were inserted into one or two messages and secondly whether participants had to answer questions about the shadowed message at the end of each passage or just remember the numbers. The DV was the number of digits correctly recalled

In experiment 3, participants were required to shadow one of two simultaneous dichotic messages. In some of the messages digits were added towards the end of the message either in both messages, or in one. The position of the numbers in the message and whether they were relative to each other in the two messages varied; controls with no numbers were also randomly inserted. One group was told they’d be asked questions about the content of the shadowed message at the end. The other group had to remember as many numbers as they could.

Experiment 3 - After statistical analysis, it was found that there were no significant results between the two groups.

Conclusion: 

When we direct our attention to a message from one ear and reject a message from the other ear, almost none of the verbal content of the rejected message is able to get through this block. The short list of simple words which were presented as the rejected message could not be remembered even when presented many times. However, ‘important’ messages, such as our own name can penetrate this block, which may be part of the rejected message. It can be concluded that it is almost impossible to make ‘neutral’ material important enough to break through the block which occurs in dichotic shadowing.

Research method: The experimental conditions and the procedures that Moray created were highly controlled in a laboratory, therefore showing high internal validity. However, due to the nature of the study and the sample, responses may have been a result of demand characteristics. Furthermore, listening to sounds through headphones and being asked to block out or shadow the noises is extremely artificial and not true to real life; therefore, the study lacks ecological validity.

Reliability: The procedures of the study, including instructions given to participants, are highly standardised which allows the study to be easily replicated and to check for the reliability of the findings.

Sampling bias: As with many psychology studies, University students took part (as well as research workers). This sample is easily accessible, so saves time and money on obtaining participants. However, the sample is not representative of everyone, as students and research workers are likely to have higher cognitive abilities and may perform better on attention tasks. Therefore the study lacks population validity.