Psychology Commons^™

Asymmetries In Motor Attention During A Cued Bimanual Reaching Task: Left And Right Handers Compared, Gavin Buckingham, Julie Main, David Carey

Gavin Buckingham

Several studies have indicated that right handers have attention biased toward their right hand during bimanual coordination (Buckingham and Carey, 2009; Peters, 1981). To determine if this behavioral asymmetry was linked to cerebral lateralization, we examined this bias in left and right handers by combining a discontinuous double-step reaching task with a Posner-style hand cueing paradigm. Left and right handed participants received a tactile cue (valid on 80% of trials) prior to a bimanual reach to target pairs. Right handers took longer to inhibit their right hand and made more right hand errors, suggesting that their dominant hand was more …

The Role Of Vision In Detecting And Correcting Fingertip Force Errors During Object Lifting, Gavin Buckingham

Gavin Buckingham

No abstract provided.

The Role Of Vision In Detecting And Correcting Fingertip Force Errors During Object Lifting, Gavin Buckingham, Nathalie Ranger, Melvyn Goodale

Gavin Buckingham

Vision provides many reliable cues about the likely weight of an object, allowing individuals to predict how heavy it will be. The forces used to lift an object for the first time reflect these predictions. This, however, leads to inevitable errors during lifts of objects that weigh unexpected amounts. Fortunately, these errors are rarely made twice in a row-lifters have the impressive ability to detect and correct large or small misapplications of fingertip forces, even while experiencing weight illusions. Although it has been assumed that we detect and correct these errors exclusively with our sense of touch, recent evidence has …

Learning From Mistakes: Improving Initial Fingertip Force Scaling By Observing Lifting Errors, Gavin Buckingham, Minnie Tang, Paul Gribble, Melvyn Goodale

Gavin Buckingham

• When lifting objects that are lighter or heaver than we expect them to be, individuals typically misapply forces in a way that reflects their prior expectations of heaviness.

• Because we lift in this predictive way, large and small cubes elicit these characteristic errors even when they are adjusted to have equal mass. Lifters will apply too much force to a large cube and substantially less force to a small cube – errors that are rapidly corrected with repeated lifts (Flanagan & Beltzner, 2000).

• When watching others lift objects, an observer’s motor system automatically reacts in a way …

The Material-Weight Illusion Induced By Expectations Alone, Gavin Buckingham, Nathalie Ranger, Melvyn Goodale

Gavin Buckingham

In the material-weight illusion (MWI), equally weighted objects that appear to be made from different materials are incorrectly perceived as having different weights when they are lifted one after the other. Here, we show that continuous visual experience of the lift is not a prerequisite for this compelling misperception of weight; merely priming the lifters' expectations of heaviness is sufficient for them to experience a robust MWI. Furthermore, these expectations continued to influence the load force used to lift MWI-inducing stimuli trial after trial, supporting the notion that vision plays an important role in the skillful lifting of objects.

Bimanual Reaching Across The Hemispace: Which Hand Is Yoked To Which?, Gavin Buckingham, Gordon Binsted, David Carey

Gavin Buckingham

When both hands perform concurrent goal-directed reaches, they become yoked to one another. To investigate the direction of this coupling (i.e., which hand is yoked to which), the temporal dynamics of bimanual reaches were compared with equivalent-amplitude unimanual reaches. These reaches were to target pairs located on either the left or right sides of space; meaning that in the bimanual condition, one hand's contralateral (more difficult) reach accompanied by the other hand's ipsilateral (easier) reach. By comparing which hand's difficult reach was improved more by the presence of the other hand's easier ipsilateral reach, we were able to demonstrate asymmetries …

The Influence Of Competing Perceptual And Motor Priors In The Context Of The Size-Weight Illusion, Gavin Buckingham, Melvyn Goodale

Gavin Buckingham

When lifting objects of identical mass but different sizes, people perceive the smaller objects as weighing more than the larger ones (the 'size-weight' illusion, SWI). While individual's grip and load force rates are rapidly scaled to the objects' actual mass, the magnitude of the force used to lift these SWI-inducing objects is rarely discussed. Here, we show that participants continue to apply a greater loading force to a large SWI-inducing cube than to a small SWI cube, lift after lift. These differences in load force persisted long after initial errors in grip and load force rates had been corrected. Interestingly, …

Gating Of Vibrotactile Detection During Visually Guided Bimanual Reaches, Gavin Buckingham, David Carey, Francisco Colino, John Degrosbois, Gordon Binsted

Gavin Buckingham

It is far more difficult to detect a small tactile stimulation on a finger that is moving compared to when it is static. This suppression of tactile information during motion, known as tactile gating, has been examined in some detail during single-joint movements. However, the existence and time course of this gating has yet to be examined during visually guided multi-joint reaches, where sensory feedback may be paramount. The current study demonstrated that neurologically intact humans are unable to detect a small vibratory stimulus on one of their index fingers during a bimanual reach toward visual targets. By parametrically altering …

Lifting Without Seeing: The Role Of Vision In Perceiving And Acting Upon The Size Weight Illusion, Gavin Buckingham, Melvyn Goodale

Gavin Buckingham

BACKGROUND: Our expectations of an object's heaviness not only drive our fingertip forces, but also our perception of heaviness. This effect is highlighted by the classic size-weight illusion (SWI), where different-sized objects of identical mass feel different weights. Here, we examined whether these expectations are sufficient to induce the SWI in a single wooden cube when lifted without visual feedback, by varying the size of the object seen prior to the lift.

METHODOLOGY/PRINCIPAL FINDINGS: Participants, who believed that they were lifting the same object that they had just seen, reported that the weight of the single, standard-sized cube that they …

Lifting Without Seeing: The Role Of Vision In Perceiving And Acting Upon The Size‐Weight Illusion, Gavin Buckingham, Melvyn Goodale

Gavin Buckingham

Our expectations of an object’s heaviness not only drive our fingertip forces, but also our perception of heaviness. This effect is highlighted by the classic size-weight illusion (SWI), where different‐sized objects of identical mass feel different weights (Charpentier, 1891) long after any initial errors in the application of fingertip forces have been corrected (Flanagan & Beltzner, 2000).

Here, we examined whether our expectations about the weight of an upcoming lift are sufficient to induce the SWI in a single wooden cube when lifted without visual feedback, by varying the size of the object seen prior to the lift during a …

Laterality, Perception, And Action During The Size-Weight Illusion, Gavin Buckingham, Nathalie Ranger, Melvyn Goodale

Gavin Buckingham

In the classic size-weight illusion (SWI), a small object will feel heavier than an larger object of equal weight (Charpentier, 1891). Individuals continue to perceive this illusory difference in weight long after their gripping and lifting forces have scaled to the actual, identical, mass of the illusion-inducing stimuli (Flanagan & Beltzner, 2000).

The independence of our weight perception and fingertip force application has only been quantified in the right hand of right-handers. The immunity to this perceptual illusion may be affected by manual asymmetries (e.g., Gonzalez, Ganel & Goodale, 2006).

We examined perception of heaviness and fingertip force scaling in …

Living In A Material World: How Visual Cues To Material Properties Affect The Way That We Lift Objects And Perceive Their Weight, Gavin Buckingham, Jonathan Cant, Melvyn Goodale

Gavin Buckingham

The visual properties of an object provide many cues as to the tensile strength, compliance, and density of the material from which it is made. However, it is not well understood how these implicit associations affect our perceptions of these properties and how they determine the initial forces that are applied when an object is picked up. Here we examine the effects of these cues on such forces by using the classic "material-weight illusion" (MWI). Grip and load forces were measured in three experiments as participants lifted cubes made from metal, wood, and expanded polystyrene. These cubes were adjusted to …

A Dissociation Between Perception And Action In The Material‐Weight Illusion, Gavin Buckingham, Jonathan Cant, Kai-Ling Kao, Melvyn Goodale

Gavin Buckingham

We examined what forces are applied to objects that elicit this illusion when they are lifted.We predicted that:

(1) Forces on early trials will scale to each participant’s expectations of how much a particular block will weigh ‐ excessive force will be applied to the metal block and insufficient force applied to the polystyrene block.

(2) Forces on later trials will scale to the real weight of each block ‐ identical levels of force applied to all the blocks.

(3) MWI will persist throughout ‐ polystyrene block will feel the heaviest, metal block will feel the lightest.

Grasping And Lifting Different Materials, Gavin Buckingham, Jonathan Cant, Melvyn Goodale

Gavin Buckingham

The material from which an object is made can determine how heavy it feels (Seashore, 1899). Interestingly, a metal block that has been adjusted to have the same size and mass as a polystyrene block will feel lighter than the polystyrene block. We recently showed that participants experiencing this material-weight illusion’ (MWI) do not apply forces that match their perceptual experience of heaviness ‐ just like in the size‐weight illusion ( Flanagan & Beltzner, 2000).

Our previous study showed that forces on early trials were scaled to each participant’s expectations of how much a particular block should weigh ‐ excessive …

Investigating Bimanual Coordination In Dominant And Non-Dominant Virtual Hands, Gavin Buckingham, David Carey

Gavin Buckingham

A bias in attention towards the dominant hand has been cited as a possible factor in the lateralisation of human bimanual coordination (Peters, 1981). A mirror was placed between the hands of 18 dextral participants performing rhythmic anti-phase movements. This set-up gave the appearance of a reflected virtual hand (moving in time with the un-occluded hand), in the same spatial location as the occluded left or right hand. This asymmetrical conflict between vision and action examined whether the left hand would show higher levels of error when replaced by a virtual right hand than the converse condition. Higher levels of …

Visual Adaptation To Masculine And Feminine Faces Influences Generalized Preferences And Perceptions Of Trustworthiness, Gavin Buckingham, Lisa Debruine, Anthony Little, Lisa Welling, Claire Conway, Bernard Tiddeman, Benedict Jones

Gavin Buckingham

Although previous studies of individual differences in preferences for masculinity in male faces have typically emphasized the importance of factors such as changes in levels of sex hormones during the menstrual cycle, other research has demonstrated that recent visual experience with faces also influences preferences for sexual dimorphism in faces. Adaptation to either masculine or feminine faces increases preferences for novel faces that are similar to those that were recently seen. Here, we replicate this effect and demonstrate that adaptation to masculine or feminine faces also influences the extent to which masculine faces are perceived as trustworthy. These adaptation effects …