Mean judged weight before and after lifting while expecting to lift alone solo condition or with a co-actor joint condition. Single sample t tests showed that mean solo judgments did not significantly differ from the actual mean of These results support our prediction that boxes appear less heavy when one is intending to lift them with a partner rather than alone.
Judgments in the joint condition were lower than judgments in the solo condition not only after participants had lifted a box together, but also before they did so. However, we cannot rule out the possibility that the experience of repeatedly lifting boxes together shaped weight judgments in the joint condition.
Thus, participants may have judged the boxes as lighter simply because they felt lighter on previous trials.
Experiment 2a was designed to rule out this explanation. In this experiment, participants only made a single judgment while intending to lift a box together or alone.
Thus, they did not experience the effort of lifting jointly or individually prior to making their judgment. Furthermore, we sought to replicate the results of Experiment 1 with a different set of stimuli golf balls; see Fig. Again, we predicted that participants intending to lift the box together would judge it as lighter than participants intending to lift it alone.
Photograph of the basket of golf balls a , and results of Experiment 2a b. They were randomly assigned to one of two conditions. Eight students 5 female participated in the joint condition, and eight different students 5 female participated in the solo condition. Students participated for partial fulfillment of a course requirement and provided informed consent. Participants were tested individually and sat in one corner of the experimental room. The basket remained hidden from view until all instructions were given. The experiment consisted of a single trial.
Participants were instructed to judge the weight of the box, then get up and lift it either alone in the solo condition, or with the experimenter in the joint condition , and to then make another weight judgment. Participants wrote down their judgments on a sheet of paper that was on the desk beside them.
The experimenter served as the co-actor in the joint condition for two reasons: There was no significant difference between solo and joint judgments after lifting. These findings confirm our prediction. Even in the absence of the experience of joint lifting, participants expecting to lift a basket of golf balls with another person judged it as lighter than those expecting to lift it alone. Unlike in Experiment 1, judgments after lifting did not significantly differ between the solo and joint condition.
It could be that the difference between the solo and joint condition after lifting in Experiment 1 reflects an effect of repeated lifting. In particular, repeated lifting may have led participants in the joint condition to perceive the boxes as not so heavy, whereas participants in the solo condition might have suffered from fatigue. This effect did not occur in the present experiment, where participants only lifted the box a single time. In fact, judgments after lifting were surprisingly accurate.
They were slightly higher, though not significantly different from the actual weight. In contrast, judgments before lifting were slightly too high in the solo condition, and significantly too low in the joint condition. Taken together with the results of Experiment 1, it appears that solo judgments are generally more accurate, whereas judgments in the joint condition reflect a tendency to underestimate the actual weight. A possible explanation for this underestimation is that participants intending to act together engaged in motor simulation of their part of the joint action to be performed.
Anticipated effort, in turn, may have affected weight judgments. Experiment 2b was designed to rule out this possibility. If the effects observed in Experiments 1 and 2a were due to cognitive bias, then judgments about other properties, such as quantity i. If, on the other hand, the observed underestimation of box weight in the joint condition reflected effects of anticipated effort on perception, then judgments about quantity should not be affected by whether participants are intending to lift a box alone or together.
Motor effort, per se, reflects weight, and not quantity.
Thus, only weight judgments should be influenced as a direct effect of anticipated effort. Ten students 4 female participated in the joint condition, and 10 different students 4 female participated in the individual condition.
The same materials and procedure were used in Experiment 2b as in Experiment 2a, except for an additional request to estimate the number of golf balls in the basket. All other instructions remained identical to those of Experiment 2a. This seems to be the driving factor behind the main effect of time of judgment reported above. Results of Experiment 2b. Mean judgments of the number of golf balls before lifting were Mean judgments after lifting were As predicted, weight judgments were affected by the intention to lift alone or together while number judgments were not.
This indicates that anticipated effort rather than a cognitive bias underlies the underestimation of object weight when intending to lift objects together. Lower weight judgments before joint lifting were observed consistently across Experiments 1, 2a, and 2b as evidenced by the significant main effect of Condition for judgments given before lifting. In contrast, the pattern of post-lifting judgments varied across experiments. In Experiment 1, judgments after lifting showed the same pattern as judgments before lifting, whereas in Experiments 2a and 2b there was no difference in weight judgments after joint or individual lifting.
This can be explained by the fact that Experiments 2a and 2b only involved a single trial, so that the effort associated with repeated lifting of the box did not affect post-lifting judgments. Finally, whereas in Experiment 2a estimates in the solo condition decreased after lifting the box and estimates in the joint condition increased, in Experiment 2b, they increased in both conditions.
What could be the mechanism underlying the observed effect of intended joint action on weight judgments? The results of Experiment 2b provide some evidence that anticipated effort rather than a general cognitive bias led to the observed modulation of weight judgments. However, it could also be that sharing the intention to perform a joint action is key. In particular, a study by Schnall et al.
When participants thought about a supportive other, a hill seemed less steep to them compared to when they thought about an unfriendly person. In the joint condition, half of the participants were paired with an apparently injured co-actor, and half with a healthy co-actor Fig. To rule out effects of exposure to an injured individual, the same experimenter was present in the solo condition and appeared injured or not.
Thus, there were four between-subjects conditions: Experimenter who served as co-actor in healthy state a and injured state b. If anticipated effort plays a role in the observed effects on weight judgments, participants intending to lift a box with an uninjured co-actor should judge it as lighter than participants intending to lift it with an injured co-actor.
Weight judgments in the solo condition should be the same regardless of whether an injured or healthy person is present. Alternatively, if having a shared intention or a shared goal is critical, judgments in the two joint conditions should be the same, because in both cases, participants are intending to act together with another person. In this case, one would expect a main effect of the joint condition compared to the solo condition. Two participants were excluded because they misunderstood the instructions. The same materials and procedure were used as in Experiment 2a.
To ensure participants knew the dominant arm was injured, and to reinforce the believability of the injury, the experimenter asked participants with help in filling out their own data sheet i. If asked about the cause of the injury, the experimenter replied he had been in a minor car accident the previous weekend. After the experiment, participants were debriefed and questioned regarding the believability of the injury.
Two participants expressed doubts about the injury; therefore, their data were excluded. All others indicated they thought the injury was real, which was further evidenced by the look of surprise and laughter after finding out the truth. One participant was excluded from data analysis because her judgment prior to lifting was more than two standard deviations outside of the group mean. Thus, the analyses are based on data from 40 participants. Results of Experiment 3.
The physical state of the other person could be healthy or injured. These results show that intending to lift with another person makes the load look lighter, but only when intending to lift with a healthy person who is capable of providing a significant amount of help. Intending to lift with a seemingly injured individual i. An increased feeling of social support through shared intentions in the joint condition cannot explain the observed effects.
Rather, it seems likely that participants judged boxes as less heavy because they anticipated the effort during joint lifting. Three experiments showed that intending to lift a box together decreases judgments of its weight compared to intending to lift the same box alone, provided that the co-actor appears capable of helping. This indicates that perception is shaped not only by what we can do by ourselves but by what we can do with others.
Our findings extend earlier studies that have investigated how individual action abilities affect the perception of the environment and of object properties. These studies have consistently found that individual ability, be it determined by expertise, the availability of tools, or current fitness levels, affects how individuals judge distances to be covered, slants to be mastered, and the size and movement speed of objects to be manipulated for review, see Proffitt, ; Witt, The present findings indicate that the perception of object properties also reflects changes in individual ability brought about by interpersonal coordination.
It remains to be investigated whether joint action abilities modulate the perception of other properties apart from object weight, such as distance. How does intending to act together shape weight judgments? This could take several forms. On the one hand, one could assume that the joint affordance of boxes to be lifted together directly affects weight perception. The notion of joint affordance suggests that co-actors perceive the environment in terms of what they can do together.
For instance, an object might afford joint lifting given its length and the combined arm span of the dyad Richardson et al. One could argue that in our experiments, boxes afforded joint lifting given the presence of a healthy co-actor, and that this directly changed the perception of their weight.
We predicted that participants would judge the boxes as lighter not only after joint lifting compared to individual lifting, but also while intending to lift them jointly rather than alone. Several studies have found that around milligrams of caffeine a cup of coffee will perk you up and improve your strength. They were slightly higher, though not significantly different from the actual weight. Does this mean that all cheating is off limits? An increased feeling of social support through shared intentions in the joint condition cannot explain the observed effects.
On the other hand, it seems possible that participants simulated the action they intended to perform, relying on their own motor system Cross et al. Accordingly, the anticipated effort derived from anticipatory motor simulation Kilner et al. An interesting prediction that follows from this account is that seeing objects being lifted by two people should also make them look lighter compared to objects that are being lifted by a single person.
Finally, although the accuracy of the weight judgments varied somewhat across the three experiments, it is noteworthy that people tended to be less accurate in the joint action context, consistently underestimating the weight of the boxes to be lifted together. This is consistent with a view where our perceptual system is optimized for guiding our interactions with the environment rather than deriving action-independent object properties.
In a context where engaging in joint action is a possibility, it may be highly useful to be able to anticipate common effects in order to decide when and with whom to collaborate. In fact, one could speculate that effects of anticipated joint action on perception might act as a driving force for collaboration. While this remains to be explored, the findings reported in this study lead us to conclude that the joint action abilities of a group shape the individual perception of its members. This article is distributed under the terms of the Creative Commons Attribution Noncommercial License which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author s and source are credited.
National Center for Biotechnology Information , U. Published online Dec 9. Received Jul 22; Accepted Nov This article has been cited by other articles in PMC. Abstract The action abilities of an individual observer modulate his or her perception of spatial properties of the environment and of objects. So, if you find that your form starts to suffer on your last few reps of these bigger, more complex movements, your neurological system may have hit its limit, Trink says.
Try performing fewer reps per set. The goal is to really focus on your form so that your body learns the proper technique as early on as possible. A lot more weight. Luckily, since you are performing a lot of reps, you are still going to see improvements in your muscle tone. Still, fight the urge to skip ahead. You should keep your strength workouts structured like this for eight weeks, moving up in weight as you feel comfortable.
You should be able to increase your weight by two to five percent each week, he says. Keep a strength training log with your number of reps, sets and pounds lifted to track your progress and see growth. During this next phase of your training, which can last up to six months, you are going to lift more weight, getting closer to your one-rep max aka your 1RM, the most you can lift for a single rep.
Three to four sets of eight to 10 reps is a good range, Trink says. You should aim to have one rep in the tank after each set, she says. And, remember, you should be keeping up the killer form you learned during your first months in the weight room. Fight the urge to use momentum and give yourself two minutes or more between sets, she says. Work on progressing to higher weights and fewer sets, capping your reps at six and above per set, Trink says. If so, you should add exercises focused on those muscles to the mix, starting all the way back at step one.