Biomedical subjects

Rob Ellis

Publications and source records attributed to Rob Ellis.

5 recordsLinked to original sources

PubMed2006

Local and global affordances and manual planning.

The present study aimed to demonstrate that motor planning processes are affected by ignored affordances of a main body of an object. Participants were asked to select the hand of response according to the property of the local component (a stalk) of the object (a fruit) while they were holding a precision or a power grip devices. The size of a main body of an object was observed to prime hand selection processes asymmetrically. Right-hand responses were facilitated when the stalk was a part of a precision grip object (e.g. a strawberry) or displayed alone. In contrast, left-hand responses were facilitated when the stalk was a part of a power grip object (e.g. an apple). This data supported our previously presented view that the different hemispheres have differential roles in the early planning of manual actions. The object information that is relevant to precision grip planning appears to be processed predominantly in the left-hemisphere whereas the information that is relevant to power grip planning appears to be processed predominantly in the right-hemisphere. In Experiment 3, the irrelevant fruit body had a slight effect on motor planning even though the stalk was spatially separated from the fruit body. The priming effect was entirely eliminated when, in addition to the spatial separation, the stalk was semantically disassociated from the fruit body (Experiment 4), and when the objects used in Experiment 1 were replaced by two dimensional abstract objects (Experiment 2). Experiments 2, 3 and 4 suggested that affordances of an irrelevant main body of an object influences motor planning processes only when the local target component of the object is analysed as a meaningful part of a graspable object.

Adolescent↗

PubMed2006

Visual object affordances: object orientation.

Five experiments systematically investigated whether orientation is a visual object property that affords action. The primary aim was to establish the existence of a pure physical affordance (PPA) of object orientation, independent of any semantic object-action associations or visually salient areas towards which visual attention might be biased. Taken together, the data from these experiments suggest that firstly PPAs of object orientation do exist, and secondly, the behavioural effects that reveal them are larger and more robust when the object appears to be graspable, and is oriented in depth (rather than just frontally) such that its leading edge appears to point outwards in space towards a particular hand of the viewer.

Adult↗

PubMed2006

Manual asymmetries in visually primed grasping.

Previous research has shown that the task irrelevant size of familiar objects facilitates compatible precision and power grip responses. The present study examined whether the task irrelevant size of novel objects produces the same compatibility effect. However, the main objective of the study was to investigate whether visually primed precision and power grips are manually asymmetric. Experiment 1 showed that the size of a novel prime object does facilitate compatible precision and power grips, even when both the object itself and the grasp type are irrelevant to the current task. However, this effect was only found when the precision grip was made with the right hand (RH) and the power grip was made with the left hand (LH). When these grips were made with the opposite hands, the effect was absent. Experiment 2 replicated the LH bias for large objects and the RH bias for small objects when power and precision grip responses were replaced with simple LH and RH button-press responses. It appears that the two hemispheres are specialised with regard to precision and power compatible objects.

Functional Laterality↗

PubMed2005

The potentiation of two components of the reach-to-grasp action during object categorisation in visual memory.

Stimulus-Response Compatibility Effects have been reported for several components of the reach-to-grasp action during visual object recognition [Tucker, M., & Ellis, R. (1998). On the relations between seen objects and components of potential actions. Journal of Experimental Psychology: Human Perception and Performance, 24, 830-846; Ellis, R., & Tucker, M. (2000). Micro-affordance: The potentiation of actions by seen objects. British Journal of Psychology, 91, 451-471; Tucker, M., & Ellis, R. (2001). The potentiation of grasp types during visual object categorization. Visual Cognition, 8, 769-800; Creem, S. H., & Proffitt, D. R. (2001). Grasping objects by their handles: A necessary interaction between cognition and action. Journal of Experimental Psychology: Human Perception and Performance, 27, 218-228; Craighero, L. Bello, A. Fadiga, L., & Rizzolatti, G. (2002). Hand action preparation influences the responses to hand pictures. Neuropsychologia, 40, 492-502]. The present study investigates compatibility effects for two elements of reach-to-grasp action during the visual mental imagery of objects-the compatibility of an object for grasping with a power and precision grasp, and the orientation of an object (left/right) for grasping by a particular hand (left/right). Experiment 1 provides further evidence for compatibility effects of a 'seen' object for grasping with a power and precision grasp. The experiment shows that compatibility effects are obtainable when an object is presented in an array of four objects and not just on its own. Experiment 2 provides evidence that compatibility effects of an object for grasping with a power and precision grasp can also be observed when participants make an action response to an object 700 ms after it has been removed from view. Experiment 3 investigates compatibility effects for the orientation of an object for grasping by a particular hand during visual mental imagery, but finds no evidence for such effects. The findings are discussed in relation to two arguments put forward to reconcile ecological and representational theories of visual object recognition.

Adolescent↗

PubMed2004

Action priming by briefly presented objects.

Three experiments investigated how visual objects prime the actions they afford. The principal concern was whether such visuomotor priming depends upon a concurrent visual input--as would be expected if it is mediated by on-line dorsal system processes. Experiment 1 showed there to be essentially identical advantages for making afforded over non-afforded responses when these were made to objects still in view and following brief (30 or 50 ms) object exposures that were backward masked. Experiment 2 showed that affordance effects were also unaffected by stimulus degradation. Finally, Experiment 3 showed there to be statistically equal effects from images of objects and their names. The results suggest that an active object representation is sufficient to generate affordance compatibility effects based on associated actions, whether or not the object is concurrently visible.

Humans↗