Seeing and feeling volumes: The influence of shape on volume perception

Mass distribution and shape influence the perceived weight of objects

Research suggests that the rotational dynamics of an object underpins our perception of its weight. We examine the generalisability of that account using a more ecologically valid way of manipulating an object's mass distribution (mass concentrated either at the top, bottom, centre, near the edges or evenly distributed throughout the object), shape (cube or sphere), and lifting approach (lifting directly by the hand or indirectly using a handle or string). The results were in line with our predictions. An interaction effect was found where the mass distribution and lifting approach both associated with the lowest rotational dynamics made the stimulus appear lighter compared to other combinations. These findings demonstrate rotational dynamic effects in a more run-of-the-mill experience of weight perception than what has been demonstrated before using cumbersome stimuli.

Effect on Perceived Weight of Object Shapes

The perceived weight of an object is an important research topic in terms of sensation and perception, and it is known that it has size-weight, color-weight, and material-weight illusions due to the influence of size, color, and material, as well as the weight of the object. Although the physical size of an object is measured by volume, the size of an object that we subjectively feel depends on the shape of the object, even if it has the same volume. Therefore, the shape of the object may determine the perceived size of the object, thereby changing its perceived weight accordingly. These cognitive factors play an important role in the period of rehabilitation therapy after an exacerbation or attack of neurological diseases, such as stroke or Parkinson's disease, regarding the motor functions of the patient. Moreover, the study of these sensation and perception factors is important for the period of the early development of children, for example, for tracking and correcting fine motor skills. Existing related studies analyzed the perceived weight according to three shapes (tetrahedron, cube, and sphere), but only some shapes showed a difference in the perceived weight. This study attempted to demonstrate the difference in perceived weight according to the shape that has yet to be clearly identified. To this end, this study investigated objects with the same physical size (volume) as in previous studies, but in the shapes of tetrahedron, cube, and sphere. In addition, the volumes of these objects were set to 64,000 cm³, 125,000 cm³, and 216,000 cm³, and their weights were set to be 100 g, 150 g, and 200 g, in proportion to the size of the small, medium, and large volumes, respectively. Thirty-eight college students (21 males, 17 females) participated and the perceived weight of a given object compared to a reference object was evaluated according to the modulus method used for sensory size measurement. The analysis of the experimental data found that both weight (volume) and shape had significant effects on the perceived weight. The results support that the shape of objects also led to the size-weight illusion phenomenon. At the same weight (volume), the perceived weight of an object according to shape decreased significantly in the order of sphere, cube, and tetrahedron. At the same volume level, subjective size according to shape is small in the order of tetrahedron, cube, and sphere. The results of weight perception according to shape in this study showed that the subjective size of an object according to shape had an effect on perceived weight.

Not a matter of shape: The influence of tool characteristics on electrodermal activity in response to haptic exploration of Lower Palaeolithic tools

OBJECTIVES

Haptics involves somatosensory perception through the skin surface and dynamic touch based on the proprioceptive response of the whole body. Handling Palaeolithic stone tools influences the arousal and attentional engagement, which can be detected and measured through electrodermal activity. Although tool shape has generally been studied to consider tool functions or tool making, it is also a major factor in tool sensing and haptic perception. The purpose of this survey is to analyze whether the electrodermal reactions are influenced by stone tool morphology.

METHODS

We first quantify the morphological variability of 72 stone tools through geometric morphometrics. Then, 12 stone tools from the previous sample were randomly selected to perform the electrodermal analysis in a sample of 46 right-handed adults.

RESULTS

Elongation is the main factor involved in Lower Palaeolithic shape variation, followed by the position of the maximum thickness. Attention and manipulation time are mainly influenced by tool size, while arousal mostly correlates with tool weight. Electrodermal activity is apparently not influenced by the overall tool shape. Tool size, weight, and base morphology are the variables that mainly trigger an electrodermal reaction.

CONCLUSIONS

Electrophysiological reaction is more sensitive to specific physical features of the tool than to its general outline. These features are not particularly different in worked pebbles and handaxes in terms of grasping, but underwent remarkable changes in other technological traditions. That changes associated with behavioral performances can be employed in cognitive archaeology to investigate the relationships between tool sensing and tool use.

Shitsukan - the Multisensory Perception of Quality

We often estimate, or perceive, the quality of materials, surfaces, and objects, what the Japanese refer to as 'shitsukan', by means of several of our senses. The majority of the literature on shitsukan perception has, though, tended to focus on the unimodal visual evaluation of stimulus properties. In part, this presumably reflects the widespread hegemony of the visual in the modern era and, in part, is a result of the growing interest, not to mention the impressive advances, in digital rendering amongst the computer graphics community. Nevertheless, regardless of such an oculocentric bias in so much of the empirical literature, it is important to note that several other senses often do contribute to the impression of the material quality of surfaces, materials, and objects as experienced in the real world, rather than just in virtual reality. Understanding the multisensory contributions to the perception of material quality, especially when combined with computational and neural data, is likely to have implications for a number of fields of basic research as well as being applicable to emerging domains such as, for example, multisensory augmented retail, not to mention multisensory packaging design.

Influence of visually perceived shape and brightness on perceived size, expected weight, and perceived weight of 3D objects

In the size–weight illusion, when two objects of identical weight but different volume are lifted, the smaller object is typically perceived to weigh more than the larger object. A well-known explanation for this and other weight illusions is provided by the hypothesis that perceived weight results from the contrast between actual and expected weight. More recently, it has been suggested that an object’s size may exert a direct and automatic effect on its perceived weight, independently of expected weight. Here we test these two hypotheses by exploring two illusions that have been known for a long time but have remained relatively underexplored, namely the shape–weight and brightness–weight illusions. Specifically, we measured the influence of visually perceived shape and brightness on the perceived size, the expected weight, and the perceived weight of 3D plastic objects. A numerical rating task was used in Experiment 1, and a paired comparison task was used in Experiment 2. The results showed that spheres were perceived to be heavier than tetrahedrons and cubes, and cubes were perceived to be heavier than tetrahedrons. We did not find any consistent relationship between brightness and perceived weight. A systematic comparison between perceived size, expected weight, and perceived weight showed that the visual shape–weight and brightness–weight illusions are partially inconsistent with the hypothesis that perceived weight results from the contrast between actual and expected weight and with the hypothesis that perceived weight results from the contrast between actual weight and perceived size. The results appear to suggest that there may be a dissociation between the processing of variables that contribute to the conscious experience of size, such as brightness and vertical height, and the processing of variables that contribute to perceived weight, such as surface area.

Discrimination threshold for haptic volume perception of fingers and phalanges

Humans exhibit a remarkable ability to discriminate variations in object volume based on natural haptic perception. The discrimination thresholds for the haptic volume perception of the whole hand are well known, but the discrimination thresholds for haptic volume perception of fingers and phalanges are still unknown. In the present study, two psychophysical experiments were performed to investigate haptic volume perception in various fingers and phalanges. The configurations of both experiments were completely dependent on haptic volume perception from the fingers and phalanges. The participants were asked to blindly discriminate the volume variation of regular solid objects in a random order by using the distal phalanx, medial phalanx, and proximal phalanx of their index finger, middle finger, ring finger, and little finger. The discrimination threshold of haptic volume perception gradually decreases from the little finger to the index finger as well as from the proximal phalanx to the distal phalanx. Overall, both the shape of the target and the part of the finger in contact with the target significantly influence the precision of haptic perception of volume. This substantial data set provides detailed and compelling perspectives on the haptic system, including for discrimination of the spatial size of objects and for performing more general perceptual processes.

Being Hungry Affects Oral Size Perception

Oral size perception is not veridical, and there is disagreement on whether this nonveridicality tends to underestimate or overestimate size. Further, being hungry has been shown to affect oral size perception. In this study, we investigated the effect of hunger on oral size perception. Overall, being hungry had a small but significant effect on oral size perception and seemed to support that oral size perception tends to underestimate the size of objects. Both hungry and sated participants tended to underestimate the size of intraoral objects, but hungry participants underestimated to a significantly lesser degree. Unlike previous research, this tendency was independent of the order and number of assessments of size. We, therefore, offer a novel explanation for these findings: Oral size perception is modulated by a hierarchy of Bayesian predictions, and being hungry changes the priors in these predictions.

A Psychophysical Investigation of Size as a Physical Variable

Physical visualizations, or data physicalizations, encode data in attributes of physical shapes. Despite a considerable body of work on visual variables, "physical variables" remain poorly understood. One of them is physical size. A difficulty for solid elements is that "size" is ambiguous - it can refer to either length/diameter, surface, or volume. Thus, it is unclear for designers of physicalizations how to effectively encode quantities in physical size. To investigate, we ran an experiment where participants estimated ratios between quantities represented by solid bars and spheres. Our results suggest that solid bars are compared based on their length, consistent with previous findings for 2D and 3D bars on flat media. But for spheres, participants' estimates are rather proportional to their surface. Depending on the estimation method used, judgments are rather consistent across participants, thus the use of perceptually-optimized size scales seems possible. We conclude by discussing implications for the design of data physicalizations and the need for more empirical studies on physical variables.

Glass shape influences consumption rate for alcoholic beverages

BACKGROUND

High levels of alcohol consumption and increases in heavy episodic drinking (binge drinking) are a growing public concern, due to their association with increased risk of personal and societal harm. Alcohol consumption has been shown to be sensitive to factors such as price and availability. The aim of this study was to explore the influence of glass shape on the rate of consumption of alcoholic and non-alcoholic beverages.

METHODS

This was an experimental design with beverage (lager, soft drink), glass (straight, curved) and quantity (6 fl oz, 12 fl oz) as between-subjects factors. Social male and female alcohol consumers (n = 159) attended two experimental sessions, and were randomised to drink either lager or a soft drink from either a curved or straight-sided glass, and complete a computerised task identifying perceived midpoint of the two glasses (order counterbalanced). Ethical approval was granted by the Faculty of Science Research Ethics Committee at the University of Bristol. The primary outcome measures were total drinking time of an alcoholic or non-alcoholic beverage, and perceptual judgement of the half-way point of a straight and curved glass.

RESULTS

Participants were 60% slower to consume an alcoholic beverage from a straight glass compared to a curved glass. This effect was only observed for a full glass and not a half-full glass, and was not observed for a non-alcoholic beverage. Participants also misjudged the half-way point of a curved glass to a greater degree than that of a straight glass, and there was a trend towards a positive association between the degree of error and total drinking time.

CONCLUSIONS

Glass shape appears to influence the rate of drinking of alcoholic beverages. This may represent a modifiable target for public health interventions.

Characterization of the Haptic Shape-Weight Illusion with 3D Objects

The present study shows an effect of 3D shape on perceived weight of objects. This effect could be explained partly by the size-weight and the shape-size illusions, suggesting that the perceived size is not the only factor responsible for the shape-weight illusion.