Psychological refractory period

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In the attention -Research is called Psychological refractory period , a time interval (PRP, Eng .: Psychological Refractory Period), can be processed in which only one stimulus. The term was coined in 1952 by Alan T. Welford .

The example of an employee in a power plant can be used to illustrate the PRP effect, which describes the so-called psychological refractory period . That employee is entrusted with the monitoring of various processes. This monitoring activity is based on reacting to various warning lights on a control panel. During such an activity it can happen that two important lamps light up at the same time or only a short distance apart. This requires a double activity on the part of the employee. It is easy to imagine that he cannot react adequately quickly to both stimuli. This could have far-reaching consequences for a company.

Basic processes

Such a situation can also be created in a psychological laboratory. A test person should react as quickly as possible to two stimuli presented one after the other. This then leads to the PRP effect, a delay in the reaction to the second stimulus, i.e. an extension of the reaction time 2 to the second stimulus. The reaction time to the first stimulus is not extended, remains unchanged.

The term refractory period is biologically or neuroscientifically derived from the refractory period . What is meant here is the time that neurons need after a stimulus transfer in order to transport an action potential again. For the PRP effect, the expression implies that neurological processes are involved and that there is a delay.

Models of stimulus processing

There are primarily two models that try to explain this effect. The capacity-sharing models and the delay models. Both models assume a basic three-step stimulus processing flow. After an initial phase of sensual, often visual, perception, which depends on the stimulus properties, a central processing stage follows. This stage consists of the decisions about the possible responses and the final determination. This level of central information processing is followed by a motor level. While the capacity sharing models assume a limited pool of processing resources that must be shared between the two tasks, the delay models assume a kind of bottleneck. This bottleneck means that two identical steps cannot be carried out at the same time. This is the explanation for a reaction delay with regard to the second stimulus, since the reaction stages for the second stimulus cannot run because the reaction to the first stimulus has already started and is current at a stage. However, the reaction time for the second stimulus is not fundamentally longer and reaction 2 is therefore delayed.

Response time is the time from the presentation of the stimulus (stimulus onset) to the reaction. The interval between the two stimuli is decisive for the delay in RT 2. This interval is called the onset asynchrony stimulus , SOA for short.

Basically, the following simplified scheme applies. If the SOA is very short, an overlap between the two reaction processes (to stimulus one and two) is very likely. Somewhere in the manufacturing process, the bottleneck arises and with it a pause called "cognitive slack". On the other hand, if the SOA is so long that the bottleneck steps do not overlap, reaction 2 takes place unhindered. But this is just a basic consideration. Much more decisive for the delay theory is the location of the bottleneck. Depending on the prediction approach, other theoretical basic structures result. The bottleneck could be in the motor, in the sensory, but also, and this is the most widespread assumption, in the central stage of processing. When the results are statistically checked, the different localizations suggest that other statistical effects can be expected. The three possible effects are:

  • The subadditive effects
  • The additive effects
  • The super-additive effects

To check the localization one has to manipulate the different levels of reaction processing. One could assume that a change in the stimulus properties has an effect on the level of perception, while a simplification of the reaction decision has an influence on central processing. One such relief could be to show the stimulus to be reacted to on the side of the screen on which a button is also to be pressed.

Research conclusions

The search for the bottleneck is based on a whole series of different experiments, each with different approaches, theoretical explanations and the resulting interpretations.

In addition, there are efforts to check the effect in connection with other variables, such as exercise processes, agreement of stimulus and response modality, physiological processes and, for example, psychopathological conditions.

However, so far there is no clear result on the localization of the bottle neck when processing two different stimuli.

In general, two tasks are combined when checking the PRP effect. The single-task task and the dual-task task. The single-task task only includes single stimulus processing. It is used to calculate the response time under normal circumstances. This is determined by stimulus two. The dual-task task is the actual experimental run. This is where the PRP effect occurs.

literature

  • Welford, AT (1952): The "psychological refractory period" and the timing of high-speed performance - A review and a theory . British Journal of Psychology, 43, 219.
  • Pashler, H., & Johnston, JC (1989): Chronometric Evidence for Central Postponement in Temporally Overlapping Tasks . Journal of Experimental Psychology 41a, 19-45 (1-2).
  • McCann, RS, & Johnston, JC (1992): Locus of Single Channel Bottleneck in Dual-Task Interference . Journal of Experimental Psychology 18,471-484 (1).