The role of expectancies in the size-weight illusion: A review of theoretical and empirical arguments and a new explanation

The size–weight illusion (SWI) refers to the phenomenon that objects that are objectively equal in weight but different in size or volume are perceived to differ in weight, such that smaller objects feel heavier than larger ones. This article reviews studies trying to support three different viewpoints with respect to the role of expectancies in causing the SWI. The first viewpoint argues for a crucial role; the second admits a role, yet without seeing consequences for sensorimotor processes; and the third denies any causal role for expectancies at all. A new explanation of the SWI is proposed that can integrate the different arguments. A distinctive feature of the new explanation is that it recognizes the causal influence of expectancies, yet combines this with certain reactive and direct behavioral consequences of perceiving size differences that are independent of experience-based expectancies, and that normally result in the adaptive application of forces to lift or handle differently sized objects. The new account explains why the illusion is associated with the repeated generation of inappropriate lifting forces (which can, however, be modified through extensive training), as well as why it depends on continuous visual exposure to size cues, appears at an early age, and is cognitively impenetrable.     

Predictors of Attitudes Towards the Construction of a Waste Incinerator: Two Case Studies1

This investigation examined the predictors of the acceptance of waste incineration facilities. A survey was conducted of a random sample of the residents in two sites where an incinerator was planned (450 participants in Study 1 and 300 in Study 2). Attitudes towards the incinerator were mainly predicted by the perception of the risks as dread, positive expectancies about the project, trust in social actors involved in the process, perceived distributive justice, and distance of residence to the site. The relationship between distance of residence and attitude towards the incinerator was partially mediated by perceived risk, perceived justice, and expectations. As expected from the elaboration likelihood model, substantive peripheral cues were better predictors of attitudes for involved than for noninvolved dwellers.     

Using an AIDS KABP Survey to Identify Determinants of Condom Use Among Sexually Active Adults From St. Vincent and The Grenadines1

In Fall 1990, a knowledge, attitude, belief, and practices (KABP) survey was administered to a representative sample of residents of St. Vincent and the Grenadines, an island nation in the Eastern Caribbean. The KABP questionnaire contained a large number of questions that could reasonably be expected to be related to whether or not people use condoms. To a certain extent, each of these questions can be viewed as an attempt to assess one of the variables identified by one or more theories of behavior and behavior change. More specifically, questions on the KABP were identified as possible indicants of AIDS knowledge, cues to action, perceived susceptibility, perceived severity, perceived (locus of) control, perceived normative pressure, and condom use outcome expectancies. Statistical analyses indicated that some, but not all, of these variables were related to condom use among sexually active adults. In particular, the analyses indicated that perceived normative pressure to use condoms was the single most important determinant of condom use behaviors on St. Vincent. The implications of this finding for designing mass-media campaigns to increase condom use is discussed, and a campaign that attempts to change condom use by influencing perceived social norms is strongly recommended.     

Putting behavior on hold decreases reward value of need-instrumental objects outside of awareness

We examined whether cues that put impulsive behavior towards rewarding objects on hold reduces the value of the rewarding objects outside of conscious awareness. We manipulated the reward value of water by making participants thirsty, or not. Next, a bottle of water was subliminally presented in a go/no-go task, and paired with either go cues or no-go cues (putting behavior on hold). Subsequently, as a measure of reward value of water, participants estimated the size of water objects. Results showed that repeatedly withholding behavior towards water reduced the perceived size of water objects, but only when participants were made thirsty. These results suggest that withholding impulsive behavior towards objects that serve basic needs nonconsciously reduces reward value of these objects. Implications for nonconscious behavior regulation are briefly discussed.     

Body-based perceptual rescaling revealed through the size-weight illusion

An embodied approach to the perception of spatial layout contends that the body is used as a 'perceptual ruler' with which individuals scale the perceived environmental layout. In support of this notion, previous research has shown that the perceived size of objects can be influenced by changes in the apparent size of hand. The size-weight illusion is a well known phenomenon, which occurs when people lift two objects of equal weight but differing sizes and perceive that the larger object feels lighter. Therefore, if apparent hand size influences perceived object size, it should also influence the object's perceived weight. In this study, we investigated this possibility by using perceived weight as a measure and found that changes in the apparent size of the hand influence objects' perceived weight.     

Transport and use of common objects: Influence of weight on action planning

Internal knowledge and visual cues about object's weight play an important role in grasping and lifting objects. It has been shown that both visual cues and internal knowledge might influence movement kinematics and force production depending on action goal (use vs. transport). However, there is little evidence about weight's influence on action planning as reflected by initiation time. In the present study we investigated this issue. In Experiment 1, participants had to grasp light and heavy objects (without moving them) to either use or transport them. In Experiment 2 we asked another group of participants to actually use or transport the same objects. We observed that initiation times were faster for heavy objects than for light objects in both the transport and use tasks, but only in Experiment 2. Thus, weight influenced the planning of use and transport actions, only when the end-goal of the action was really achieved. These data are incompatible with the hypothesis that only use actions are supported by stored object's representations. They rather suggest that in some circumstances, depending of the end-goal of the action and the physical constraints the planning of both use and transport actions are based on stored object representation.     

When is a weight not illusory?

Weight illusions occur whenever some aspect of an object--such as its size, material or colour--arouses the expectation that its weight will be heavier or lighter than it actually is. The direction of the illusion normally contrasts with the expected weight. When objects are hidden from sight and lifted by strings they can provide no misleading cues, and a correct weight-expectation should be achieved after one or two trials. When a visible object has the same physical and apparent weight as a hidden object, it can be defined as non-illusory. Weighted tins and polystyrene blocks of various sizes were compared with hidden weights. Tins were found to be non-illusory when their density was about 1.7, and polystyrene blocks when their density was about 0.14.

Weight illusions may be due to a central scaling process which enables a wide range of weights to be estimated, different ranges being selected according to the expected value of the weight. If the selected range is inappropriate an illusion occurs. Changes in expected value could also allow for the operation of “weight-constancy” during changes in proprioceptive stimulation.     

社会合作信息对距离知觉的影响

为探讨社会合作信息对距离知觉的影响,本研究通过两个实验,采用动态追逐场景,对两个追逐者之间的交互模式(或合作或单独追逐同一目标)与追逐目标的存在与否进行了操作。结果发现,相比随机运动和单独追逐,存在合作关系的两个追逐者间的距离被知觉得更远,即存在距离的扩张效应(实验1),且该效应不能由底层的物理特征所解释(实验2)。该结果揭示,社会合作信息使得知觉距离被扩张,其可帮助理解视觉的适应性机制。     

The alcohol-aggression link: children's aggression expectancies in marital arguments as a function of the sobriety or intoxication of the arguing couple

Children's expectancies of man-woman and woman-man aggression during arguments between individuals who were either intoxicated or sober were examined. The role of child and familial characteristics in influencing these expectancies was assessed. We examined children's expectations of interadult verbal/psychological and physical aggression during simulated arguments presented to children on videotapes. A community sample (N = 156) of children and young adolescents (6-14-year olds) participated. Children expected higher levels of aggression during conflict when they thought that one or both participants in conflict were intoxicated versus sober. Further, higher levels of verbal versus physical interadult conflict were expected during the disputes. These findings build on the literature by demonstrating that elementary school age children and young adolescents exhibit expectancies that link the consumption of alcohol with increased verbal and physical aggression in marital arguments. These alcohol-aggression expectancies were robust and were evident in relation to either the man's or woman's perpetration of aggression against the spouse. Elucidation of factors that can influence associations between aggression and alcohol consumption are of importance and have broad implications for family functioning.     

The effect of perceived distance on induced movement

The magnitude of induced movement was measured as a function of the perceived depth between the test object and the plane of the induction object, with this perceived depth produced by stereoscopic cues. Three experiments were conducted. In each experiment, the induction object (a frame of constant physical size) was positioned at one of three distances with the test object (a point of light) placed successively at each of the three distances. Predictions of the magnitude of induction as a function of the depth separation of the test and induction object were made from the subject-relative and object-relative hypotheses of induced motion. It was expected, however, that neither of these hypotheses would predict the results independently of a factor described in the adjacency principle. This principle states that the effectiveness of whatever cues or processes determine the induced movement will decrease with increased depth between the test and induction object. The data indicate that the adjacency principle must be considered in explaining the results. The subject-relative rather than object-relative hypothesis as modified by the adjacency principle was most successful in predicting the results. Control conditions in which the frame was stationary and the point of light was physically moving were also used. Despite the fact that the relative displacement of the objects on the eye in the experimental and control conditions were the same, the results indicate that O could distinguish between these two kinds of conditions. Although the apparent movement was greater in the control conditions than in the experimental conditions, the reverse is true if the total perceived movement of the test and induction object are considered together.     

The nature of adaptation in distance perception based on oculomotor cues

In previous work by the senior authors, brief adaptation to glasses that changed the accommodation and convergence with which objects were seen resulted in large alterations in size perception. Here, two further effects of such adaptation are reported: alterations in stereoscopic depth perception and a change when distance is represented by a response of S’s arm. We believe that the three effects are manifestations of one primary effect, an alteration of the relation between accommodation and convergence on the one hand and the distance they represent in the nervous system (registered distance) on the other. This view was supported by the results of two experiments, each of which demonstrated that the alterations in stereoscopic depth perception could be obtained after adaptation periods which had provided no opportunity to use stereoscopic vision, and that the adaptation effect was larger for depth perception than for size perception when it was obtained under the same conditions; the latter finding was expected if both effects resulted from the same change in registered distance. In three of the five experiments here reported, the variety of cues that could represent veridical distance during the adaptation period was limited. In one condition of adaptation, only the pattern of growth of the retinal images of objects that S approached and the kinesthetic cues for S’s locomotion served as cues to veridical distance. In two other conditions S remained immobile. In one of these, only the perspective distortion in the projection of the scene that S viewed mediated veridical distance, and in the other one familiar objects of normal size were successively illuminated in an otherwise totally dark field, conditions from which opportunities to use stereoscopic vision were again absent. After exposure to each of these adaptation conditions, adaptive changes in perceived size and larger ones in perceived stereoscopic depth were obtained. Because we found that familiar size may serve as the sole indicator of veridical distance in an adaptation process, we concluded that it can function as a perceptual as distinguished from an inferential cue to distance.     

Negative expectancies for the group's outcomes undermine normative collective action: conflict between Christian and Muslim groups in Lebanon

In this extension of the social identity model of collective action (SIMCA; Van Zomeren, Postmes, & Spears, 2008), group expectancies are an intervening construct for the impact of group identification, perceived group inefficacy, and perceived group injustice on normative collective action. In addition to the SIMCA path from greater group identification to more action, Hypothesis 1 was that greater identification fosters less negative group expectancies, which, in turn, promote action. Hypothesis 2 was that the SIMCA path from greater perceived group inefficacy to less action is mediated by negative group expectancies. These hypotheses were for low- and high-status groups, as was the expectation for the SIMCA path from greater perceived group injustice to more action. For the low-status group, Hypothesis 3 was that perceived injustice also undermines action by fostering more negative group expectancies. During severe ethno-religious group conflict in Lebanon, university students reported on SIMCA factors and their group expectancies. Results were in line with SIMCA and Hypotheses 2 and 3, and partly with Hypothesis 1. Group expectancies are discussed in relation to likelihood of amelioration, perceived instability, and emotions. Types of expectancies are discussed, as is the relation of expectancies to normative and non-normative collective action.     

More than just skin deep? Personality information influences men's ratings of the attractiveness of women's body sizes

This study examined the influence of personality information on perceptions of the physical attractiveness of a range of female body sizes. A sample of 2,157 male university students were randomly assigned to one of 10 groups in which they received personality information about women they were rating, or a control group in which they received no personality information. Controlling for participants' age and body mass index, results showed no significant between-group differences in the body size that participants found most attractive. However, participants provided with positive personality information perceived a wider range of body sizes as physically attractive compared with the control group, whereas participants provided with negative personality information perceived a narrower range of body sizes as attractive. Correlations showed that participants' own Extraversion was associated with their body size ratings. These results suggest that non-physical cues have an influence on the perception of physical beauty.     

Going the distance: Extra-symbolic contributions to the symbolic control of spatial attention

Over the past 30 years, researchers have used symbolic cues such as spatial words and arrows to direct observers' attention to the location of target objects that appear at a single, fixed distance in simple visual environments; however, they have done so by using symbolic cues that provide only partial—directional—information about the spatial location of target objects. Thus, it remains unclear whether observers can only shift their attention broadly in the cued direction in response to these cues or whether they can shift their attention to the specific location of the target by combining an expectation about direction (derived from apprehension of the directional cue) with an expectation about distance (derived from some extra-symbolic cue). The results of two experiments showed that observers do shift their attention to relatively coarse spatial locations by combining expectancies about direction and distance, and that the extent to which observers do so is modulated by the presence of visible markers and the expected distance of the target. These findings are important because they provide the first evidence that extra-symbolic information about distance contributes to the symbolic control of spatial attention.     

Cue enhancement as a function of task set

The hypothesis was tested that the intention to use a particular cue relation would enhance the effectiveness of that particular cue in determining the resulting perception. For this purpose, a situation was presented in which the apparent depth position of an object in a configuration of objects would differ depending upon which of two possible cue relations (size cues) were used. The results support the conclusion that the perceived depth position of the object differed in the expected directions as a function of the task set. The data of the study are discussed with respect to the “adjacency principle” which states that cue efficiency is determined by the relative adjacency of objects between which the cues occur. Although the effect of cue set upon the perception seems to be small compared with that of adjacency, it cannot completely be ignored.     

Is size perception based on monocular distance cues computed automatically?

The study reported here examined whether size perception based on monocular distance cues is computed automatically. Participants were presented with a picture containing distance cues, which was superimposed with a pair of digits differing in numerical value. One digit was presented so as to be perceived as closer than the other. The digits were of similar physical size but differed in their perceptual size. The participants’ task was to decide which digit was numerically larger. It was found that the decision took longer and resulted in more errors when the perceptual size of the numerically larger digit was smaller than the perceptual size of the numerically smaller digit. These results show that perceived size affects performance in a task that does not require size or distance computation. Hence, for the first time, there is empirical support for the working assumption of the visual perception approach that size perception based on monocular distance cues is computed automatically.     

Combined perceptual or motor-related expectancies modulated by type of cue

The interaction of two expectancies was examined. These were either two perceptual or two response-related expectancies. Perceptual expectancies were induced by combining spatial cuing with feature cuing on a trial-by-trial basis. Cues consisted either of two integrated parts, such as two arrows, or two separated pieces, such as an arrow and a word. Spatial-cuing effects were reduced on trials with invalid feature cues, as compared with valid ones. However, the interaction of spatial cuing and feature cuing was modulated by the type of cue used to induce expectancies. With integrated cues, spatial-cuing effects were reduced about twice as much as with separated cues. The same effect of type of cue was found in Experiment 2, although finger cuing was combined with hand cuing. With integrated cues, finger-cuing effects were much smaller on trials with invalid hand cues, as compared with valid ones. With separated cues, however, finger-cuing effects were additive to hand-cuing effects. The similarity of the results within perceptual- and motor-cuing tasks suggests that a general principle governs the combination of expectancies, such as that outlined in the framework of the proposed adjusted expectancy model.     

Adaptation in distance perception based on oculomotor cues

Accommodation and convergence primarily serve to adjust the eyes to the distance of the object viewed, but, once made, these oculomotor adjustments serve as cues for the object’s distance. Experiments are reported that show that the relation between oculomotor adjustments and the distances they signify can be changed by adaptation to glasses that cause alteration in the oculomotor adjustments with which objects are viewed. This changed relation manifested itself in marked alterations of size perception. Wearing, for 30 min, glasses that caused a change in accommodation and convergence corresponding to a smaller object distance and equivalent to 1.5 lens diopters caused subsequent mean size increases that ranged from 50% to 65%. Adaptation to glasses that changed oculomotor adjustments in the same amount but in the opposite direction resulted in decreases in perceived sizes that varied from 18% to 40%, dependent on the distance of the test object. These were the results of size estimates obtained before and after the adaptation period under conditions where only accommodation and convergence served as cues for distance. A newly developed test of size perception was also used, in which S adjusted the size of the projected image of an array of familiar objects on a screen until the size of the objects appeared normal. Again, such adjustments were made before and after the adaptation period, and size differences were obtained that were in the direction to be expected of adaptation and varied in amount between 12% and 33%, dependent on the distance of the screen. The reason for the different amounts of size change measured by the two kinds of tests was investigated.     

The look of love: gaze shifts and person perception

Gaze direction is a vital communicative channel through which people transmit information to each other. By signaling the locus of social attention, gaze cues convey information about the relative importance of objects, including other people, in the environment. For the most part, this information is communicated via patterns of gaze direction, with gaze shifts signaling changes in the objects of attention. Noting the relevance of gaze cues in social cognition, we speculated that gaze shifts may modulate people's evaluations of others. We investigated this possibility by asking participants to judge the likability (Experiment 1) and physical attractiveness (Experiment 2) of targets displaying gaze shifts indicative of attentional engagement or disengagement with the participants. As expected, person evaluation was moderated by the direction of gaze shifts, but only when the judgment under consideration was relevant to participants. We consider how and when gaze shifts may modulate person perception and its associated behavioral products.