|Year : 2013 | Volume
| Issue : 4 | Page : 179-181
Effect of number of stimuli on auditory reaction time in healthy subjects of Bhavnagar region
Tejas P Ghuntla, Hemant B Mehta, Pradnya A Gokhale, Chinmay J Shah
Department of Physiology, Government Medical College, Bhavnagar, Gujarat, India
|Date of Web Publication||7-Jan-2014|
Tejas P Ghuntla
“Maa Sharda”, Plot No. 13, Sumeru Bunglows, Opp. Top-3 Cinema, Talaja Road, Bhavnagar - 364 002, Gujarat
Source of Support: None, Conflict of Interest: None
Background: Present study aimed to see effect of number of stimuli on auditory reaction time. Reaction is purposeful voluntary response to different stimuli as auditory stimuli. Auditory reaction time is time required to response to auditory stimuli. Materials and Methods: The auditory reaction time was measured by the reaction time instrument in subjects. Simple reaction time and choice reaction time measured. During the reaction time testing, auditory stimuli were given for three times and minimum reaction time was taken as the final reaction time for that sensory modality of that subject. The results were statistically analyzed and were recorded as mean ± standard deviation and Student's paired t-test was applied to check the level of significance. Results and Conclusion: The study shows that simple auditory reaction time is less than choice auditory reaction time. Mental processes are involved in identification of stimulus, response selection, and programming and this takes certain time. Response to stimuli would be faster if number of stimuli is lesser in number. In routine life, many works done on information of auditory stimuli. Person should be careful while driving in talking with others or in mobiles. Training reduces reaction time. In medical examination, there are identification of instruments, graphs, bones, and viva questions as well. Student can practice and decrease mental processing time for identification of all this and can respond quickly.
Keywords: Auditory, Choice, Reaction time, Simple, Stimuli
|How to cite this article:|
Ghuntla TP, Mehta HB, Gokhale PA, Shah CJ. Effect of number of stimuli on auditory reaction time in healthy subjects of Bhavnagar region. Indian J Otol 2013;19:179-81
|How to cite this URL:|
Ghuntla TP, Mehta HB, Gokhale PA, Shah CJ. Effect of number of stimuli on auditory reaction time in healthy subjects of Bhavnagar region. Indian J Otol [serial online] 2013 [cited 2019 Apr 20];19:179-81. Available from: http://www.indianjotol.org/text.asp?2013/19/4/179/124510
| Introduction|| |
Reaction time is defined as interval of time between presentation of stimulus and appearance of appropriate voluntary response in a subject.  Human body responses to number of external environmental stimuli of different modalities. Human body gives a desired and purposeful voluntary response to stimulus. There is certain time period between application of stimulus and appropriate motor response. There are various sensory modalities and human body responses to various stimuli with different speed. This plays important role in every day life as well as in emergency survival as while driving it is necessary to give break as quickly as possible to vehicle when required. Reaction time becomes an important component of information processing, as it indexes speed of stimulus processing and response programming. 
In addition to the use of other senses, auditory sense is widely used in health care, transportation, and industrial environments as it has an immediate arousing effect,  as sometimes while driving vehicle persons listens horns of more than one vehicle and accordingly takes decision for driving as well one would give way to ambulance on listening to horn of ambulance. Auditory reaction time is time required to respond to auditory stimuli.
With the recognition that impaired decision making is prominently associated with various mental disorders, , decision making has attracted good attention in the studies of cognition and in psychiatry. 
Reaction time is having mainly two components  : (1) Mental processing time-which is time required for responder to perceive stimulus, identifying and analyzing of stimulus, and decide the proper motor response. (2) Movement time-it is time required to perform movement after selection of response. Luce  and Welford  described three types of reaction time.  (1) Simple reaction time-here there is one stimulus and one response. (2) Recognition reaction time-here there are some stimulus that should be responded to and other that should not get response. (3) Choice reaction time-here there are multiple stimulus and multiple responses.
In simple reaction time, stimulus and response is one, so to complete task only identification of stimulus and its proper response required. While in choice reaction time stimulus and appropriate response are multiple, after identification of stimulus out of many, one response out of many has to be verified. So in choice reaction time task more mental process is involved, which would require certain more time. It is logical from this that choice auditory reaction time would be more than simple auditory reaction time. The pioneer reaction time study was that of Donders.  He showed that a simple reaction time is shorter than a recognition reaction time, and that the choice reaction time is longest of all.
In present study, we compare simple auditory reaction time and choice auditory reaction time to observe effect of number of stimuli on auditory reaction time, in healthy subjects of Bhavnagar region.
| Materials and Methods|| |
Study was conducted in 50 male healthy subjects of Bhavnagar region. Personal history and medical history of all subjects was collected in predesigned performa. Medical history was taken to rule out any medical or surgical disease which would affect reaction time of individual. After taking consent, reaction time was measured with multiple choice apparatus 653 MP (reaction time apparatus), an Inco company product (Ambala), with accuracy of ± 0.001 s. Auditory reaction time was measured under two categories. (1) Simple reaction time, where subject has to respond to auditory stimuli by pressing key, and (2) choice reaction time, where subject has to respond to different auditory stimulus by pressing respective key. For auditory stimuli low and high frequency pure sounds were given. Subjects were given practice session in which the subject responded to auditory stimuli till near about constant values of reaction time come and then auditory stimuli were given for three times and minimum reaction time was taken as a final reaction time for that sensory modality of that subject.
Data were collected and was statistically analyzed. Reaction time was taken as mean ± standard deviation. The level of significance simple auditory reaction time and choice auditory reaction time was tested by Student's t-test (paired). The observation was taken as a significant of P value less than 0.05.
| Results|| |
Auditory reaction time found to be significantly (P value less than 0.05) less in simple reaction time task as compared to choice reaction time task [Table 1].
|Table 1: Difference in simple auditory reaction time and choice auditory reaction time in 50 subjects|
Click here to view
| Discussion|| |
In the present study, we found that simple auditory reaction time is less than choice auditory reaction time, which means that reaction time is larger on increasing number of stimuli. This is in parallel with previous studies concluding that an increasing number of stimulus/response elicits a slower reaction time. ,,
Several possible mechanisms have been described for this. Decision making often involves the accumulation of information over time, but acquiring information typically comes at a cost.  Information processing is primarily responsible for the difference between simple and choice reaction time.  In choice reaction time the uncertainity of stimulus and information load was greater as probability of stimulus was more than single. 
Surwillo  reported that reaction was faster when a single tone sounded than when either a high or a low tone sounded or the subject was supposed to react only when the high tone sounded. In simple reaction time, the response can be specified in advance, and the stimulus does not need to be identified. The subject needs merely to register that it has occurred.  In the simple reaction time task, there is single response so response can be preprogrammed before presentation of the stimulus. While in choice reaction time task, response is stimulus driven so preprogramming is not possible and the correct response is selected, prepared, and initiated only after presentation of the stimulus. 
Previous studies  also found that the response on choice reaction time task was significantly longer than simple reaction time task. Many investigators have studied the effect of increasing the number of possible stimuli in recognition and choice experiments. Hick  found that in choice reaction time task, response was proportional to log (N), where N is the number of possible stimuli.
In a typical choice reaction time paradigm, a set of stimuli is associated with a set of responses, usually with a one-to-one mapping of stimuli onto responses. Research involving this paradigm has revealed that as set size (the number of stimulus-response alternatives) increases, RT becomes longer.  A typical choice reaction time paradigm in which set-size effects is observed requires retention of a set of stimulus-response associations in memory. ,,,,,, When a stimulus is presented on a trial, its associated response has to be retrieved from memory. Set-size effects partly arise from this act of memory retrieval.  In some studies, , set-size effects for key press responses is obtained. 
When stimulus is multiple, responder not only detects stimulus but also recognize that which signal occurred and then mentally program correct response. This mental process requires certain time and slows reaction. 
| Conclusion|| |
Auditory reaction time increases with increase in number of stimuli. In day to day life, plenty work is done on basis of auditory stimuli. Information can be helpful in routine life as while driving person should use be careful in responding to talk of companied person or in mobiles. Training reduces reaction time.  It is helpful to students, as they have identification of bones, instruments, graphs, and viva questions in examination of various medical subjects. So by practice students can identify, understand, and answer quickly.
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