The Effects of Action on Perception. Andriana Tesoro. California State University, Long Beach

Transcription

1 ACTION ON PERCEPTION 1 The Effects of Action on Perception Andriana Tesoro California State University, Long Beach

2 ACTION ON PERCEPTION 2 The Effects of Action on Perception Perception is a process that allows people to interpret sensory information that they receive from the environment through sight, smell, touch, taste, and sound. It is a process that involves top-down processing and bottom-up processing. Top-down processing occurs when behavior and perception is driven by cognition, while bottom-up processing occurs when perception directs cognition or behavior, allowing humans to make decisions and behave differently based on their perceptions. Using both processes together allows people to have better perception of their environment and how to act according to their environment better. According to the theory of affordances, perceptions are adjusted based on the actions that the environment affords. Various aspects in the environment such as a person s skills and abilities or intended action can influence the way people perceive their environment. For the purpose of demonstrating the effects of action on perception, five research experiments were conducted each displaying that perception can be distorted based on a person s intended actions, skills, and abilities. According to a meta-analysis of her own research, Jessica K. Witt displayed that the way people perceive the environment is based on a person s ability to act in it. This research was conducted to prove to critiques that actions do not affect our judgment of the environment; it affects the way we perceive the environment instead. Witt was trying to prove that there is evidence for action-specific perception, which allows people to perceive their environment based on their ability to act in it. For example, a person that is extremely skilled in a specific sport such as baseball or tennis will perceive the ball as larger because of their sports ability. According to Witt, some factors that affect ability and therefore affect perception include a person s body size, body control and coordination, energetic potential, and task-related challenges. Witt conducted

3 ACTION ON PERCEPTION 3 her meta-analysis by analyzing past experiments done by her and many other researchers on these effects. Testing the effects of body size on perception was done through tool-use manipulation. Witt and her colleagues manipulated participants body size by using tools such as a baton to extend the arm length of participants. Participants were either told to use tools to extend their reach or not to use the tools in order to touch a target. They were then asked to record how far they believed the target was from them. The results of these tasks display that a person s abilities to perform an action affects the way that they perceive their environment because when participants were able to use tools to extend their reach to touch targets, the targets appeared closer than when they were not able to use tools to reach targets beyond their reach. Witt and colleagues experimented on the effects of body control and coordination by analyzing the control and coordination that a variety of sports professionals have on their bodies and how they perceive their environment based on their ability to control their movements. For example, parkour experts with training that allows them to climb and jump over walls see walls as shorter. This distortion of perception can be explained with theory of affordances because a short wall affords the action of climbing for these professionals. By analyzing the performance and perception of sports professionals, Witt was able to find that there are three factors that influence their ability and thus affects their perception. A person s overall control of the situation, which can be developed through training, a person s moment-to-moment ability, such as how tired or energized a person is, and a person s thoughts before and after the action all affect their ability to perform the intended action, which therefore affects their perception of the environment. Witt also found that a person s ability to do the task is also affected by the difficulty of the task. If a task is difficult for the person to perform, the person perceives the environment in which the task is made as a hindrance to performing the task, while in an environment in which the task is easy,

4 ACTION ON PERCEPTION 4 the task is perceived as helpful for performing the task. They also found that the amount of energy needed to put into the task also affects a person s ability to perform and their perception of the environment. Through the results of these experiments, Witt and her colleagues found that various factors affect action ability, which therefore affects people s perception in terms of size, coordination, energetic potential, and the demands of the task. They were able to prove that action affects perception rather than judgment because other experiments only instructed participants to look at an object and predict their ability to perform an action with it rather than allowing them to act on their goals like in the current experiments of Witt and colleagues. In another experiment done by Witt, she worked with Proffitt and Epstein to investigate if a person s ability to reach a target could change their perception of the environment. According to past research that Witt, Proffitt, and Epstein looked at, tool use activates reachability neurons that allow the person to adapt to changes in reachability, and behavioral differences occur because of our ability to reach targets or not. These differences in reachability therefore affect the amount of personal space that people perceive to have. Personal space is remapped with tool use and thus affects visual attention within that space. If something is out of reach for a person, it is out of their personal space and they perceive it as far. When that person uses tools to extend their reach, the size of their personal space becomes bigger, and the target is seen as closer because it is within their personal space. The theory of affordances is used again to explain why these events occur. Witt, Proffitt, and Epstein hypothesized that having a strong link between action and perception through tool use affects a person s ability to act and directly influences the way they perceive the world. They did three experiments to test this hypothesis in which they manipulated the personal space of each participant through baton reaching or hand reaching. All three experiments were conducted by sitting each participant in front of a white

5 ACTION ON PERCEPTION 5 rectangular table onto which stimuli were projected from a projector on the ceiling. There was also a wooden handle at one end of the table, which specified the location from which participants were to measure the distance to the target from. During the first experiment, there were two blocks of trials, one where a baton was used and the other where a baton was not used. Participants were told by a computer-generated voice to either estimate or touch a 2-centimeter circle target that was projected onto the table. If the circle was within reach during touch trials, the participants were to reach out and touch it with a baton or their finger, and if it were out of reach participants were to point to where it was with a baton or their finger. During estimate trials, the participants had to verbally estimate the distance between the wooden handle and the circle in inches. There were twenty distances that the target varied between cm to cm throughout the trials. The results of the first experiment displayed that when a tool such as the baton was used, targets that were beyond reach were estimated to be closer to the participants than when the participants had to point it with their finger. The second experiment was conducted on 8 participants, 2 of which were men and 6 of which were women, with the same set-up as the first experiment except a white paper circle was used in place of the wooden handle. During this experiment, the participants had to match the distance between the circle and the target with the distance between two comparison circles. The participants had to move the comparison circles closer together or farther apart to match the distance between the the white paper circle and the target. Half of the trials were conducted with a baton while the other half were conducted just using the participants fingers. The results of this experiment were the same as the first, the participants personal space expanded with baton use making targets that were out of reach is perceived as closer. According to the researchers the baton allowed the participants to remap the amount of personal space that they had, and therefore the targets

6 ACTION ON PERCEPTION 6 seemed closer. For the third experiment, Witt and colleagues tested a new hypothesis stating that simply holding a baton and not reaching should not affect perceived distance. This experiment was conducted on 8 participants, half of them being men and the other half, women, under the same conditions of Experiment 2 except they never reached the targets just either held the baton or not. Through the third experiment, the researchers found that just holding a tool does not affect spatial perception, the participants perceived the targets to be at the same distance with or without the baton. In order for spatial perception to become distorted, participants had to have the intention of acting on something. After all of the experiments were conducted, Witt, Proffitt, and Epstein found that perceived distance is only affected by tool use when people have the intention of using it, which supports their main hypothesis. Research conducted by Wykowska, Schubö, and Hommel further demonstrates that actions affect visual perception, especially when it is planned. Like many other researchers, Wykowska, Schubö, and Hommel believe that perception is an interaction between bottom-up processing and top-down processing. They believe that preparing to act on something in the environment allows us to pay more attention to things that are more relevant for that situation and allow people to have better control of the situation. Action planning therefore affects visual perception because action planning allows for top-down processing to occur and putting emphasis on relevant things in the environment during planning allows bottom-up processing to occur. In order to test that their hypothesis of action planning is correct, three experiments were conducted. Each experiment consisted of two sessions, a practice session and an experimental session with four blocks of either pointing or grasping actions and two blocks of both types of actions randomly intermixed, with 64 trials in each block. All three experiments were also conducted using a movement execution device (MED) designed with round plastic items in

7 ACTION ON PERCEPTION 7 various sizes and luminance for the participants to perform grasping or pointing movements on. For the first experiment, 12 people participated (6 men, 6 women) between the ages of 18 and 30 years old. Participants had to prepare to either point at or grasp at an item that was lit based on the movement cue that was given to them. The researchers predicted that preparing a grasp movement would make grasping a size-defined target easier than grasping a target that was luminance defined, and pointing at a luminance-defined target would be easier than pointing to a size-defined target because they would be trained to do so. After the first experiment, their hypothesis was proved to be correct and the results also displayed that preparing to point at a target produced faster reaction times than preparing to grasp a target. The second experiment investigated if the prevention of top-down processing and tempting participants to rely on saliency signals only would work against action-induced biasing. This experiment was conducted using the same design as Experiment 1 except both the task-relevant dimension and movement type were varied and the participants were to respond to pop-out targets and decide whether a target was presented or not. The results of this experiment confirmed the hypothesis that adopting only a bottom-up strategy would eliminate the impact of action planning on selection. They showed that action planning could not occur; leading to the slowest responses for blank trials, intermediate responses for size trials, and fastest responses for luminance trials. When trials were repeated, it led to pop-out targets, which also allowed for faster reaction times than when trials had different dimensions. In the third experiment, they did the opposite of what occurred in Experiment 2. They prevented bottom-up processing and tempted participants to use top-down processing to detect targets by having them search for a specific task-relevant target. By doing so, according to Wykowska, Schubö, and Hommel s hypothesis, it should allow actioninduced biases to influence target selection. There were 17 participants (9 men, 8 women) in this

8 ACTION ON PERCEPTION 8 study ranging between the ages of 20 and 36 years old. The procedure remained the same as Experiment 2 except for the instructions given. Participants were instructed to respond to size targets by pressing the target-related key after a size target was defined and an alternative key when a luminance target appeared after it was defined by a lighter grey. The results found in this experiment show slower reaction times for size than for luminance and slower reaction times for target absent trials. Experiments 2 and 3 show the effects of using bottom-up processing and topdown processing separately leading to slower reaction times as opposed to using both processes together. All three experiments show that action planning allows people to perceive things that are more relevant to that action, such as grasping smaller objects rather than bigger objects or objects that are supposed to be pointed at. A fourth study conducted by Bloesch, Davoli, Roth, Brockmole, and Abrahms examined if the perception of space could be affected by observing the actions of others even without the intention of performing the action themselves. They wanted to see if perception occurs in the same way for the person performing the action as for the person just observing. According to Bloesch and colleagues, the effect of action and just observing on perception could be the same because people adjust their attention to what their partner is doing, be it their eye gaze, head gaze, pointing, or implied body motion. Two experiments were conducted to examine these effects. The hypothesis of the first experiment was that if observation can cause spatial perception to become compressed, then the observer s estimates of distance should be similar to the person performing the action. For the second hypothesis, they wanted to see if observing a remote interaction would produce the same effect. The first experiment was conducted on 32 participants who worked in pairs and were each randomly assigned to be an actor or observer. A ball was placed on a table at ten possible randomized locations all beyond the reach of

9 ACTION ON PERCEPTION 9 participants, ranging from 75 cm to 105 cm away. The participants were instructed to either point at the ball using their arm or using a tool, a 65 cm long pointing stick. After observing either pointing action, the observers were instructed to provide a written estimate of the target s distance in any unit of measure that they felt comfortable in reporting. The results of the first experiment display that their hypothesis was correct. Observers estimated the targets to be closer when the actors reached the ball with the pointing stick than with their arm, which is the same perceptual distortion experienced by the actors. During the second experiment there were 36 participants and it was constructed in a basement hallway 42.5 m long and 2.6 m wide. A shooting target was placed at 8 possible randomized locations in the hallway from 1.8 m to 30.5 m from both participants. This time the actors were instructed to point to the target with a remote control laser pointer of a metal baton while the observer had to again estimate the distance between his partner and the target using their most accurate unit of measurement, which was later converted into meters by the researchers. At the end of each trial, both participants were instructed to turn around so that the experimenters could adjust the target to its new location without the participants seeing. The results found in Experiment 2 show evidence that their second hypothesis was correct. Even through the use of remote control tools to reach targets, perceived distance can be compressed making targets appear closer. According to Bloesch et al., there are two reasons why these results occurred. The first reason is that the same brain regions are active when performing an action and when observing an action, and the second reason is that the deployment of attention (eye gaze, head gaze, etc.) is the same for both the actor and the observer. This research displays how observing actions allows people to become more successful in performing those actions in the future.

10 ACTION ON PERCEPTION 10 The last study also involved the use of remote control lasers. Davoli, Brockmole, and Witt examined if remote tool-use could compress perceived distance whether it is real, imagined, or remembered. They conducted this research because little research has been done in the past examining the effects of tools used at far distances on perceptual distortion. In order to analyze the effects of remote tool-use on visual perception, three experiments were conducted with the hypothesis that any type of tool-use, in this case remote tool-use could lead to perceptual distortion when participants illuminate objects with a laser pointer compared to those who do not use a laser pointer, whether it be real, imagined, or remembered. Each experiment was conducted in a basement hallway 42.5 m long and 2.6 m wide with the target placed at 8 possible locations away from the observer. The first experiment was divided into three parts. Experiment 1A examined the effects of real remote tool-use. Researchers wanted to see is perceptual compression would occur even through remote interaction with the environment where the distant object was unable to be physically reached. In this part of Experiment 1, there were 40 participants. During the experiment, each participant was instructed to point at the targets with either a laser pointer or a baton and to report the estimated distance to the target from where they were standing in the hallway. The results after Experiment 1A was conducted, demonstrated that targets pointed at with the laser pointer were estimated as closer than those pointed at with a baton. This shows that when people can actually observe that an action occurs even at a distance, it can compress perceived distance. Experiment 1B examined the effect of no tool-use on perceived distance. It was conducted to see if the laser pointer causes a compression of perceived distance while a baton causes expansion. During this part of Experiment 1, there were 20 participants and the same procedure was conducted as in Experiment 1A except the participants held no tools, instead the held their arms to their sides. The results of Experiment 1B does not

11 ACTION ON PERCEPTION 11 support the hypothesis that pointing at a target with a baton causes an expansion of perceived distance, while still supporting the idea that tool use compresses perceived distance. Experiment 1C examined the effect of imagined tool use on perceived distance. Here, they determined that if spatial compression still occurs even through imagined tool-use, then visual feedback is not needed to change perceived distance between objects. In this experiment, there were 20 participants and it was set up the same way as Experiments 1 and 2 except the laser pointer did not have batteries and the participants had to imagine that they were using the pointer properly. The results of this experiment showed that visual feedback is not needed to produce compression in perceived distances but it is affected by intended action, similar to the results found in the study done by Wykowska, Schubö, and Hommel. A second experiment was done to examine if perception is sensitive to the intention of action. Experiment 2 was conducted to see if the intention of bringing objects closer or moving them farther away would affect perceived distance. There were 30 participants in this experiment with the same procedural design as in Experiment 1 but while holding the nozzle of a vacuum, which was used to either draw the target in closer or push the target away. After this experiment was conducted, the results found were that any type of intended action, whether it be pulling an object in closer or pushing it away, leads to perceived distance compression because of the intended action. Lastly, Experiment 3 was conducted to examine the usage of the compressed perceived space produced by remote tool-use. They wanted to see if participants remembered their environment as spatially compressed. In this experiment, there were 39 participants that were instructed to generate a story about the different scenes that were mounted on the walls of the hallway. This allowed researchers to see if perceptual distortion has the capacity to exist in memory, which is what results of this experiment supported. According to Davoli, Brockmole, and Witt, the intention of

12 ACTION ON PERCEPTION 12 performing an action alters a person s spatial distribution of attention. These three experiments show evidence that an alteration in attention leads to an alteration in perception, which then lead to a person s potential behavior. Perception allows humans to make better sense of the world and how to act in it. It is how we interpret the sensory information that we receive from our environment to determine our individual behavior, ability to perform an action, and helps us survive. Through the use of both top-down and bottom-up processes, people have better perception of their environment and how to act according to their environment. Both processes also allow for the theory of affordances to take place, which adjusts our perception based on the actions that the environment affords. Each of the five studies that were summarized show evidence of how perception can be affected by our actions, whether it is through a person s body size, tool-use, a person s intended actions, a person s abilities, and even just through observation. These factors distort perception; making it compressed or expanded depending on the person s actions in trying to reach their goals. Being aware of these perception-changing factors could help designers make products that are safe and effective for all people to use no matter how their perception changes.

13 ACTION ON PERCEPTION 13 References: Bloesch, E.K., Davoli, C.C., Roth, N., Brockmole, J., & Abrahms, R.A. (2012). Watch this! Observed tool-use affects perceived distance. Psychonomic Bulletin & Review. doi: /s z Davoli, C.C., Brockmole, J.R., & Witt, J.K. (2012). Compressing perceived distance with remote tool-use: Rea, imagined, and remembered. Journal of Experimental Psychology: Human Perception and Performance, 38, doi: /a Witt, J.K. (2011). Action s effect on Perception. Current Directions in Psychological Science, 20, doi: / Witt, J.K., Proffitt, D.R., & Epstein, W. (2005). Tool use affects perceived distance but only when you intend to use it. Journal of Experimental Psychology: Human Perception and Performance, 31, doi: /p5090 Wykowska, A., Schubö, A., & Hommel, B. (2009). How you move is what you see: Action planning biases selection in visual search. Journal of Experimental Psychology. Human Perception and Performance, 35, doi: /a