They were randomly assigned to one of the experiments. Thirty participants were randomly assigned to either Experiment 1, 2 or 3 such that ten participants participated in each of these experiments. Another forty participants 20 per group took part in Experiment 4.
Seven of the participants in the no vision group had also participated in either Experiment 1 or 2. All participants were naive as to the purpose of the experiment. They had normal or corrected to normal vision and none of the participants reported any known somatosensory deficits. Informed consent was obtained from all participants prior to participation in the experiments. The experiment was part of a program that was approved by the ethical committee of the Faculty of Behavioural and Movement Sciences at VU University.
The experiments were carried out in accordance with the approved guidelines. These slabs were the same size for all objects, and an object consisted of two of these slabs connected using thin PVC spacers 0. By pushing the shorter spacer further into the holes in the PVC slabs, the visible length of the spacer varied while the actual length of the spacer varied much less.
Therefore, the set of objects had a uniform mass and varied in size along a single dimension Fig. By choosing equally shaped slabs of PVC for all objects, correctly estimating the volume of material between the different objects is facilitated, as using differently shaped objects can lead to biases in perceived volume and weight In Experiments 1 and 2, the objects were presented in the orientation as shown in Fig.
In Experiment 3 we additionally used a 4. In Experiment 4 we used a set of objects made out of metal Duralumin, 2.
There were also two larger objects. Participants always grasped the objects along the variable axis. A small visual control experiment was conducted to assess how well participants could visually judge the volume of material in the spacer-object. Nine participants were recruited among the department staff for a very quick assessment of how well participants would be able to compare the volume of material in solid objects to a spacer-objects.
The participants were shown a set of comparison objects and were asked to indicate which of these contained the same volume of material as the simultaneously shown 6-cm spacer-object. Participants were quite accurate at this task as the answers varied only between the 4 and the 4. The average was 4. Even if the spacer was taken into account this was an overestimation given that the spacer had a volume of only 0.
This indicates that participants were relatively accurate at comparing the volume of material between a solid and spacer-object, but tended to overestimate the volume of the spacer-object by 7. In all experiments each object was presented 10 times in each experimental condition. In Experiment 2 the conditions were performed in separate blocks while in the other experiments conditions were randomly interleaved.
In experiment 4 we presented the objects in random order. In order to ensure that all conditions were distributed over the experiment or block , the objects were presented in groups of trials in the other experiments. In every group of trials, each of the objects was presented once per condition.
Participants were never aware that the objects were presented in trial groups, nor were they aware of the total number of objects in an experimental set. Participants were seated at a table on which the objects were presented. This ensured that participants never saw more than one object at the same time and they were not aware of the total number of objects in the set.
In Experiment 2 and the no vision condition of Experiment 4 the objects were presented behind a curtain such that they were obstructed from view. On trials without vision the participants waited for a verbal signal from the experimenter indicating they could grasp and lift an object. The objects were always placed in the same location such that participants could easily grasp them in the absence of vision.
Prior to each of the experiments participants performed a couple of practice lifts with an object that was not part of the experimental set to become familiar with the task.
The magnitude of the illusion was calculated by first converting for each participant all heaviness ratings in an experiment from arbitrary units into z -scores to be able to compare between participants. All statistical tests were performed on the z-scores. To obtain values that are easier to interpret, we subsequently converted the z-scores into perceived heaviness in units of grams based on the difference in z-score between objects that actually differed in mass.
This ratio was determined on the population level and used to transform the z -score values for all objects in each of the conditions into perceived heaviness. In principle this is only an axis transformation of the z-scores. How to cite this article : Plaisier, M.
Object size can influence perceived weight independent of visual estimates of the volume of material. The authors would like to thank P. Douven, S. Castenmiller and L. Author Contributions M. Both authors reviewed the manuscript. National Center for Biotechnology Information , U.
Sci Rep. Published online Dec 2. Myrthe A. Plaisier a, 1 and Jeroen B. Smeets 1. Jeroen B. Author information Article notes Copyright and License information Disclaimer. Received Feb 10; Accepted Nov 4. This work is licensed under a Creative Commons Attribution 4.
This article has been cited by other articles in PMC. Abstract The size-weight illusion is the phenomenon that the smaller of two equally heavy objects is perceived to be heavier than the larger object when lifted. Open in a separate window.
Figure 1. A set of objects that visually contain the same volume of material, but differ in size spacer-objects. Results Experiment 1 In the first experiment we tested whether the size-weight illusion is based on information about the volume of material in an object.
Figure 2. Results of Experiment 1, averaged over participants for the different object sizes in both conditions. Experiment 2 In Experiment 2 we tested whether we can explain the results of Experiment 1 by assuming that participants experienced a considerably reduced weight illusion in both conditions of Experiment 1 due to visual information about the objects obtained from previous trials.
Figure 3. Results of Experiment 2. Experiment 3 The size of our objects varied only along one axis, the other two axes were kept constant 6 cm. Figure 4. Find a chemistry community of interest and connect on a local and global level. Technical Divisions Collaborate with scientists in your field of chemistry and stay current in your area of specialization.
Explore the interesting world of science with articles, videos and more. Recognizing and celebrating excellence in chemistry and celebrate your achievements. Diversity in Chemistry Awards Find awards and scholarships advancing diversity in the chemical sciences.
Funding to support the advancement of the chemical sciences through research projects. ACS-Hach Programs Learn about financial support for future and current high school chemistry teachers. Students will be able to explain that the density of a substance has to do with how heavy it is compared to the size of the object. Students will also be able to explain that density is a characteristic property of a substance. Assessment does not include density or distinguishing mass and weight.
Although the standard does not call for density to be used as a characteristic property to identify a substance, a basic introduction to density is included here as an optional element of a learning progression leading up to a middle school understanding of density. Download the student activity sheet and distribute one per student when specified in the activity. The activity sheet will serve as the Evaluate component of the 5-E lesson plan. Students will record their observations, and answer questions about the activity on the activity sheet.
If students dip the tiny piece of clay in the water beforehand and then put it back on the surface of the water, it should sink. Show the Animation — Density: Clay and Water. Explain that density has to do with how heavy something is compared to its size. As you show the animation, explain that since a piece of clay weighs more than the same amount, or volume, of water, clay is more dense than water. Since clay is more dense than water, a ball of clay sinks in water, no matter how big or small the ball of clay is.
Show the Animation — Density: Wood and Water. If you compared the weight of wood and an equal amount, or volume, of water the sample of wood would weigh less than the sample of water. This means that wood is less dense than water. Since wood is less dense than water, wood floats in water, no matter how big or small the piece of wood is. The key to floating is being light for your size. So if you can add size to an object without adding much weight, the object will be lighter relative to its size.
This means that the density of the overall object will decrease and be more likely to float. Ask students to describe how this principle can be used to explain how a lifejacket can help someone float in water. The key to sinking is being heavy for your size.
Our bodies are mostly water, so our density is fairly close to that of water. Because of this, an average person needs only a little bit extra buoyancy to float. A life jacket provides this extra lift. Changing Density You can change the density of a substance by heating it, cooling it, or by adding something to it.
There are two possible ways to make that object float, however:. Archimedes : Greek mathematician, physicist, engineer, inventor and astronomer c. In other words, the buoyancy is equal to the weight of the displaced fluid. For example, when an object goes into water, it displaces the water. EDinformatics Mass, Volume, Density. ProTeacher Collection Density. Objectives Demonstrate how the distribution of molecules in a substance determines its density. Investigate the relative densities of liquids and the relative densities of solids.
Demonstrate understanding of the relationship between density and buoyancy by building a boat. Materials see individual activities for materials. There are a few possibilities: Atoms of one substance might be a similar size yet have more mass than the atoms of another substance. Atoms of one substance might be a similar mass but be smaller, so more of them fit within the same volume. Atoms of one substance might be arranged in a way that allows more of them to fit in the same volume.
There are two possible ways to make that object float, however: Increase the density of the water so that the water becomes denser than the object. For example, an egg will usually sink in a glass of water, because it is denser than water.
Adding salt to the water increases the density of the water, allowing the egg to float. This experiment also works with people, but you need a lot of salt try the ocean, or even better, the Dead Sea! Increase the volume of the object so that the object becomes less dense than the water.
A great example of this is ice floating in water. Ice is formed by freezing water. When it freezes, it increases in volume as the water molecules move farther apart to accommodate the lattice structure of ice. Because the ice is now less dense than water, it floats.
0コメント