The effects of “finger pointing and calling” on cognitive control processes in the task-switching paradigm

Abstract

“Finger pointing and calling (FPC),” also known simply as “pointing and calling,” is an operational procedure to prevent human error and has been used extensively in Japanese industry. Although the effectiveness of FPC has been widely recognized, cognitive processes underlying FPC have not been thoroughly investigated. The current study focused on the effect of FPC on cognitive control processes responsible for the supervisory attentional system including the retrieval and activation of working memory. In the experiment, a task-switching paradigm was adopted. Twenty participants had to make a binary decision about two presented digits according to one of three task rules. Task rules to be applied were presented by a cue immediately before presenting the digits. Participants took part in a mixed rule session in which they had to switch the task rule from one trial to the next, and a single rule session in which a specific rule was applied throughout the session. FPC to the cue was incorporated. Results showed that in the mixed rule condition, the reaction was significantly faster when FPC was performed compared to when FPC was not performed. Even though the reaction became faster in the mixed rule condition with FPC, the accuracy of response was not affected. However, the preparation time, which was required for retrieving and activating the rule used for the current trial, was affected by performing FPC. In addition, the level of subjective mental workload did not change by applying FPC, which suggests that FPC was nonintrusive to the main task. These findings suggest that FPC facilitates the cognitive control processes of the supervisory attentional system, and that FPC was especially useful for the signal that requested operators to select something from memorized alternatives according to the content of the signal.

Relevance to industry

The findings of this study provide evidence of the effectiveness of FPC and contribute to encouraging the introduction of FPC to real working situations as a tool to prevent operational errors. The findings can also serve to evaluate the effectiveness of FPC by evaluating to what extent cognitive control processes are included when an operator has to check or respond to signals. If a check and response to a signal demands cognitive control processes, it seems to be effective to incorporate FPC into the checking and response behavior. Furthermore, the findings of this study may contribute to updating policies regarding the application of FPC and to improving safety training programs in which FPC is incorporated in the training process.

Introduction

In modern working situations, most working processes are computerized and automated by implementing information and communication technologies (ICT), and most tasks executed by human operators mainly involve monitoring the status of processes and sometimes executing simple physical responses such as pressing a button or touching a screen. While the physical load for operators has been minimized, operators still have to manage an enormous amount of information compiled by the information systems. An improved human–computer interface contributes to reducing the operator's information-processing load by mediating between a human operator and a computer system, but the human operator is still usually responsible for making and carrying out critical decisions and controls. If a human operator makes erroneous decisions and/or makes mistakes in control operations, and if the system does not deal with this human error, it is impossible to avoid problems and accidents. Therefore, efforts are continuing to be made to reduce the risk of human operator error. These efforts include improving the user-interface design and implementing fail-safe and fool-proof concepts to the system. In addition to these measures, it is important to train and encourage operators to incorporate a procedure that reduces the possibility of making mistakes.

Even in the modern industry that has been highly computerized and automated, the performance of human operators remains an important factor for accident prevention and efficiency improvement. For example, human error in maintenance tasks is an important problem for ensuring safety and reliability in many industries, such as in aviation, nuclear power plants, chemical plants, medical services, mining, etc (Dhillon and Liu, 2006). In the airline industry, human error in the maintenance activities causes accidents and other troubles such as delays in aircraft availability. Latorella and Prabhu (2000) stated that human error in aviation maintenance tasks includes defective components, missing components, wrong components, incorrect configurations, incorrect assembly sequences, functional defects, tactile defects, and procedural defects. Latorella and Prabhu (2000) proposed several approaches to reduce human error: (1) training, (2) job design and organizational considerations, (3) workspace and ambient environment design, (4) task equipment and information design, and (5) automation. Training for improving performance while preventing human error has been extensively studied (e.g., Brunstein and Gonzalez, 2011; Chan and Chiu, 2009; Czaja and Drury, 1981; Gramopadhye et al., 1998; Liang et al., 2010; Nalanagula et al., 2006). In the present study, we are focusing on a procedure to check the actions necessary to perform tasks required in a working situation. It can be introduced into industry through the training for human operators.

In Japanese industry, finger pointing and calling (FPC), which is called “shisa-kosho” or “shisa-kanko” in Japanese, have been traditionally practiced as a tool for preventing human error. FPC is an operational procedure to ensure accurate information acquisition and recognition and/or to perform motor responses accurately. In the typical FPC, an operator first makes visual contact with the target (e.g. meters, lamps, buttons, etc.) to be checked or to be controlled manually, stretches the arm out in the direction of the target, points at the target with the index finger, and calls the name and/or the status of the target aloud. When an operator needs to manipulate the target, an operator actually manipulates it after completing the procedure mentioned above. There are many variants of FPC among industrial fields in Japan. FPC developed spontaneously from on-site work practices of the Japanese rail industry and was later regulated as an official procedure to confirm that conditions were safe. Nowadays, FPC is accepted as an effective procedural tool for preventing human error and is widely used in many industries in Japan. Moreover, FPC is systematically incorporated in many occupational safety training systems. For example, the Japan Industrial Safety and Health Association offers a safety training program to predict underlying hazards in a work situation, and FPC is incorporated in this program.

Although FPC is accepted as an effective procedure for preventing human error and is widely used in industry, the effectiveness of FPC has not been sufficiently studied, aside from a few published reports (Haga et al., 1996; Kiyomiya et al., 1965). In the research by Kiyomiya et al. (1965), which was the earliest experimental study of FPC according to Haga et al. (1996), participants were required to respond to one of five visual stimuli presented in random order. In addition, participants were asked either to carry out FPC, to point to the stimulus, to call out the status of the stimulus indicated, or to do nothing before making a response to the visual stimulus. The results showed that carrying out FPC significantly reduced errors. Haga et al. (1996) conducted a psychological experiment which was based on Kiyomiya et al. (1965) and found that FPC did actually reduce the occurrence of human error (Experiment 1). Moreover, they conducted another experiment (Experiment 2) to examine how FPC affected the prevention of human error when the reaction was activated by an improper visual signal, and the results indicated that FPC significantly reduced this type of human error. Haga et al. (1996) explained that the effectiveness of FPC was associated with (1) a confirmed visual contact with the target, (2) a continuous orientation of attention to the target, as well as facilitated memorization by recall and vocalization of the target, (3) an enhanced cognitive process by using multiple sensory modalities, and (4) an increased activation by using muscular movement. The findings obtained in these previous studies have served as the evidence to justify the implementation of FPC in work situations as a measure to prevent human error.

One of the important potencies of FPC is to intentionally make a worker control each step of an action sequence. As a result, the behavior of FPC slows down and its accuracy is thus promoted. FPC is useful when emphasizing accuracy over speed. FPC is particularly useful for some habitual behaviors such as confirming that the doors and windows are locked before going outside. By checking the locks on each door and window using FPC, the risk to forget to lock any doors and windows can be reduced. In other words, human error such as action slips (Norman, 1981) is likely to be averted when using FPC. However, FPC is not useful when emphasizing speed over accuracy. For example, when we play sports or video games, we have to take prompt and immediate actions. In this case FPC is not useful or even harmful because FPC blocks the smooth execution of the action sequence. Perhaps FPC is useful in most situations in real life because in many ways we have to do something accurately at the cost of speed.

Recently, there has been an increased need to study the cognitive process underlying FPC because some negative effects of traditional FPC have been revealed in Japanese industry. For example, in situations where there are a lot of signals to be checked and an operator is asked to perform FPC with all of them, the frequency of carrying out FPC is increased, and more time is needed for it. In this situation, an operator will be very busy, and an unacceptably high load may be induced by performing FPC, resulting in an increase in operator fatigue and/or human errors induced by time pressure. Because FPC essentially emphasizes accuracy over speed, workers inevitably feel conflicted about using FPC when both speed and accuracy are required to do work.

One solution for such a situation is to modify the FPC procedure. By modifying the procedure, FPC is feasible in a high intensity load situation while still being able to maintain its effectiveness at a similar level as when FPC is performed in the traditional way. To achieve this goal, it is necessary to clarify the cognitive processes underlying FPC and to identify a component cognitive process that can be modified without negatively affecting the overall effectiveness of FPC. It may be possible to make FPC more effective by modifying it in order to facilitate one of the component cognitive processes included in it. For example, Watanabe et al. (2005) suggested the modification of FPC based on the findings of psychological studies on action events. In their experiment, when participants carried out FPC along with operation instructions presented sequentially, they were asked to perform the actual action each instruction referred to. This modification was devised based on the studies of “subject-performed tasks (SPTs)” (Englekamp, 1998; Nilsson, 2000). In the SPTs studies, participants were required to memorize verbal commands and to perform the action that each verbal command indicated, with the result that the performance of an action facilitated the recall of verbal commands. It was predicted that this action rehearsal with FPC would facilitate encoding the sequence of instructed actions. The results showed that the implementation of rehearsed actions with FPC had a positive effect on memory performance.

Furthermore, by identifying why FPC is effective for preventing human error in terms of cognitive science, the implementation of FPC in work situations is taken as an evidence-based safety measure. It also makes safety training programs that include FPC more persuasive.

Fig. 1 depicts the hypothetical effect of FPC on cognitive control processes, which is based on the supervisory attentional system (SAS) model proposed by Norman and Shallice (1986). In this model, human behavior was controlled by two systems: contention scheduling and supervisory attentional system (SAS). Finger pointing has an effect on the perceptual stage of information. By pointing a finger, visual attention is oriented and focused at the target position with more certainty where the information is displayed. The effect of FPC on the orientation of visual attention was examined in previous studies (Shinohara et al., 2009; Ariga and Watanabe, 2009). Shinohara et al. (2009) examined the effect of FPC by using a spatial cueing paradigm (Posner, 1980). FPC was performed to the cue indicating the position of an incoming visual stimulus. The results showed that FPC, particularly pointing, facilitated the detection of the visual target. Ariga and Watanabe (2009) examined various pointing gestures as a cue to trigger an automatic attentional shift and found that gesture cues caused a reflexive attentional shift to the pointed position and that indexical pointing gestures had a relatively persistent cueing effect. In addition, Watanabe et al. (2005) argued that visual contact with the target to be operated contributed to a positive effect of FPC with an action by facilitating the planning of an action sequence. It is thought that encoding of visual information and related cognitive processes is facilitated by focusing visual attention on the target by finger pointing.

According to the SAS model, perceived information is thought to trigger several schemas, with the result that some behaviors which are associated with the activated schema are evoked. Coordination of activated schemas is responsible for the contention scheduling. These processes are relatively automatic and are underlying in familiar situations. On the contrary, when the perceived information is novel or unfamiliar, the supervisory attentional system intervenes in the activation process of schemas. The supervisory attentional system, which is equivalent to the central executive of the working memory system (Baddeley and Hitch, 1974; Baddeley and Logie, 1999), has many cognitive functions such as coordination of the memory system, control of encoding and retrieval strategies, switching of attention, and mental manipulation of material in slave systems (Baddeley and Logie, 1999).

Task switching is known to be closely related to the central executive function (Gopher et al., 2000; Kramer et al., 1999; Monsell, 2003; Rogers and Monsell, 1995) and has been extensively studied. In the typical task switching paradigm, several tasks are prepared and participants are asked to perform one of them. When participants have to change the task from one trial to the next, they have to retrieve and reactivate the task set that is necessary to perform a specific task. Several studies (Baddeley et al., 2001; Bryck and Mayr, 2005; Emerson and Miyake, 2003; Miyake et al., 2004; Saeki and Saito, 2004) involved experiments in which task switching was combined with articulatory suppression. Articulatory suppression involves saying an irrelevant word repeatedly and is a commonly used technique to impose a load on the phonological information processing of the working memory system. Task switching performance has been shown to interfere with articulatory suppression, suggesting that task switching is based on phonological representation of a task set or rule which is necessary to perform the task. This task set or rule has to be retrieved and activated every time participants prepare the incoming task using a rule that is different from the one used for the previous task.

Even though no studies have yet been done that examine the effect of FPC on supervisory attentional control or the central executive, these preceding findings obtained in the study of working memory suggest that vocalizing the target information aloud (i.e. doing the “calling” in FPC) are related to the selective activation process of memorized information which is essential for performing the task. Thus, FPC is presumed to facilitate the activity of the supervisory attentional system and as a result, intentional monitoring of the activation of schemas is expected to be more efficient. Even when the operator is familiar with the situation and the operator's behavior can be automatically executed, the chance to intervene in an intentional control of the supervisory attentional system may be enhanced by vocalizing the target information aloud. It may contribute to preventing slip-type human errors (Reason, 1990).

The purpose of this study was to examine the cognitive processes in FPC by focusing on the facilitating effect of FPC on the supervisory attentional system or the central executive of the working memory system. A task-switching paradigm was used and FPC was incorporated. FPC was performed to the task cue indicating the task rule which was used in the current trial, and the performance with and without FPC was compared. It was hypothesized that the performance would be better when FPC was performed, particularly in the condition when the task rule was randomly switched from one trial to the next because FPC would support the function of the supervisory attentional system and facilitate the process of retrieval and activation of task rules.