Conflict in object affordance revealed by grip force

Psychological Research-psychologische Forschung, 2021

Habituated response tendency associated with affordance of an object is automatically inhibited if this affordance cue is extracted from a non-target object. This study presents two go/no-go experiments investigating whether this response control operates in response selection processes and whether it is linked to conflict-monitoring mechanisms. In the first experiment, the participants performed responses with one hand, and in the second experiment, with two hands. In addition, both experiments consisted of two blocks with varying frequency of go conditions (25%-go vs. 75%-go). The non-target-related response inhibition effect was only observed in Experiment 2 when the task required selecting between two hands. Additionally, the results did not reveal patterns typically related to conflict monitoring when go-frequency is manipulated and when a stimulus-response compatibility effect is examined relative to congruency condition of the previous trial. The study shows that the non-target-related response inhibition assists hand selection and is relatively resistant to conflict-monitoring processes.

Stimulus position is coded even if it is task-irrelevant, leading to faster response times when the stimulus and the response locations are compatible (spatial Stimulus–Response Compatibility–spatial SRC). Faster responses are also found when the handle of a visual object and the response hand are located on the same side; this is known as affordance effect (AE). Two contrasting accounts for AE have been classically proposed. One is focused on the recruitment of appropriate grasping actions on the object handle, and the other on the asymmetry in the object shape, which in turn would cause a handle-hand correspondence effect (CE). In order to disentangle these two accounts, we investigated the possible transfer of practice in a spatial SRC task executed with a S–R incompatible mapping to a subsequent affordance task in which objects with either their intact handle or a broken one were used. The idea was that using objects with broken handles should prevent the recruitment of motor information relative to object grasping, whereas practice transfer should prevent object asymmetry in driving handle-hand CE. A total of three experiments were carried out. In Experiment 1 participants underwent an affordance task in which common graspable objects with their intact or broken handle were used. In Experiments 2 and 3, the affordance task was preceded by a spatial SRC task in which an incompatible S–R mapping was used. Inter-task delays of 5 or 30 min were employed to assess the duration of transfer effect. In Experiment 2 objects with their intact handle were presented, whereas in Experiment 3 the same objects had their handle broken. Although objects with intact and broken handles elicited a handle-hand CE in Experiment 1, practice transfer from an incompatible spatial SRC to the affordance task was found in Experiment 3 (broken-handle objects), but not in Experiment 2 (intact-handle objects). Overall, this pattern of results indicate that both object asymmetry and the activation of motor information contribute to the generation of the handle-hand CE effect, and that the handle AE cannot be reduced to a SRC effect.

Brain and cognition, 2011

How do humans interact with tools? Gibson (1979) suggested that humans perceive directly what tools afford in terms of meaningful actions. This “affordances” hypothesis implies that visual objects can potentiate motor responses even in the absence of an intention to act. Here we explore the temporal evolution of motor plans afforded by common objects. We presented objects that have a strong significance for action (pinching and grasping) and objects with no such significance. Two experimental tasks involved participants viewing objects presented on a computer screen. For the first task, they were instructed to respond rapidly to changes in background colour by using an apparatus mimicking precision and power grip responses. For the second task, they received stimulation of their primary motor cortex using transcranial magnetic stimulation (TMS) while passively viewing the objects. Muscular responses (motor evoked potentials: MEPs) were recorded from two intrinsic hand muscles (associated with either a precision or power grip). The data showed an interaction between type of response (or muscle) and type of object, with both reaction time and MEP measures implying the generation of a congruent motor plan in the period immediately after object presentation. The results provide further support for the notion that the physical properties of objects automatically activate specific motor codes, but also demonstrate that this influence is rapid and relatively short lived.► How do objects automatically activate specific motor plans known as “affordances”? ► Task-irrelevant pictures shown to activate congruent grip actions. ► Affordance effect evident in both RTs and motor evoked potentials. ► Affordance effect arises rapidly and also dissipates quickly. ► Affordance effect evident for separate hand actions generated in the same hemisphere.

palm.mindmodeling.org

Recently, researchers have suggested that when we see an object we automatically represent how that object affords action . However, the precise nature of this representation remains unclear: is it a specific motor plan or a more abstract response code? Furthermore, do action representations actually influence what we perceive? In Experiment 1, participants responded to an image of an object and then made a laterality judgment about an image of a hand. Hand identification was fastest when the hand corresponded to both the orientation and grasp type of the object, suggesting that affordances are represented as specific action plans. In Experiment 2, participants saw an image of a hand before interpreting an ambiguous object drawing. Responses were biased towards the interpretation that was congruent with the grasp type of the hand prime. Together, these results suggest that action representations play a critical role in object perception.

Journal of Experimental Psychology: Human Perception and Performance, 2017

Correspondence effects based on the relationship between the left/right position of a pictured object's handle and the hand used to make a response, or on the size of the object and the nature of a grip response (power/precision), have been attributed to motor affordances evoked by the object. Effects of this nature, however, are readily explained by the similarity in the abstract spatial coding of the features that define the stimulus and response, without recourse to object-based affordances. We propose that in the task context of making reach-and-grasp actions, pictured objects may evoke genuine, limb-specific action constituents. We demonstrate that when subjects make reach-and-grasp responses, there is a qualitative difference in the time course of correspondence effects induced by pictures of objects versus the names of those objects. For word primes, this time course was consistent with the abstract spatial coding account, in which effects should emerge slowly and become apparent only among longer response times. In contrast, correspondence effects attributable to object primes were apparent even among the shortest response times and were invariant across the entire response-time distribution. Using rotated versions of object primes provided evidence for a short-lived competition between canonical and depicted orientations of an object with respect to eliciting components of associated actions. These results suggest that under task conditions requiring reach-and-grasp responses, pictured objects rapidly trigger constituents of real-world actions. Public Significance Statement Our experiments examine the relationship between the perception of objects and knowledge about their associated actions. We propose that when observers have an intention to make some form of hand action, such as grasping a handled object, they are likely to activate knowledge about the motor actions typically applied to objects they perceive. We demonstrate separate influences of action representations typically associated with an object, and actions that are invited by the object's perceived orientation (e.g., an object may be lying on its side). We show that both types of action knowledge may be available simultaneously and may compete when the observer is cued to make one specific action. Aspects of the relationship between object perception and action may provide clues to understanding neurological disorders in which patients are unable to identify objects or are impaired when trying to properly interact with them using manual actions.

Attention, perception & psychophysics, 2021

A widely held though debatable claim is that the picture of an object like a frying pan automatically elicits features of a left/righthanded grasp action even in perceptual tasks that make no demands on the observer to consider the graspable properties of the depicted object. Here, we sought to further elucidate this claim by relying on a methodology that allowed us to distinguish between the influence of motor versus spatial codes on the selection of a left/right-handed response while electroencephalographic data were recorded. In our experiment, participants classified images of frying pans as upright or inverted using a left/ right key press or by making a left/right-handed reach-and-grasp action towards a centrally located response element while we recorded electroencephalographic (EEG) data. In line with previous evidence (Bub, Masson, & van Noordenne, Journal of Experiment Psychology: Human Perception and Performance, 47(1), 53-80, 2021), these two modes of responding generated distinct correspondence effects on performance induced by the same set of images. In terms of our EEG data, we found that neither motor (the lateralized readiness potential) nor visual (N100 and P100) potentials were sensitive to handle-response hand correspondence. However, an exploratory theta analysis revealed that changes in frontal theta power mirrored the different correspondence effects evoked by the image on key press responses versus reach and grasp actions. Importantly, our results provide a link between these disparate effects and the engagement of cognitive control, highlighting a possible role of top-down control processes in separating motor features from the task-irrelevant features of an object, and thus in claims regarding object affordances more generally.

2014

Frontiers in Psychology, 2013

Perception and action are tightly linked: objects may be perceived not only in terms of visual features, but also in terms of possibilities for action. Previous studies showed that when a centrally located object has a salient graspable feature (e.g., a handle), it facilitates motor responses corresponding with the feature's position. However, such so-called affordance effects have been criticized as resulting from spatial compatibility effects, due to the visual asymmetry created by the graspable feature, irrespective of any affordances. In order to dissociate between affordance and spatial compatibility effects, we asked participants to perform a simple reaction-time task to typically graspable and non-graspable objects with similar visual features (e.g., lollipop and stop sign). Responses were measured using either electromyography (EMG) on proximal arm muscles during reaching-like movements, or with finger key-presses. In both EMG and button press measurements, participants responded faster when the object was either presented in the same location as the responding hand, or was affordable, resulting in significant and independent spatial compatibility and affordance effects, but no interaction. Furthermore, while the spatial compatibility effect was present from the earliest stages of movement preparation and throughout the different stages of movement execution, the affordance effect was restricted to the early stages of movement execution. Finally, we tested a small group of unilateral arm amputees using EMG, and found residual spatial compatibility but no affordance, suggesting that spatial compatibility effects do not necessarily rely on individuals' available affordances. Our results show dissociation between affordance and spatial compatibility effects, and suggest that rather than evoking the specific motor action most suitable for interaction with the viewed object, graspable objects prompt the motor system in a general, body-part independent fashion.

The visualization of tools and manipulable objects activates motor-related areas in the cortex, facilitating possible actions toward them. This pattern of activity may underlie the phenomenon of object affordance. Some cortical motor neurons are also covertly activated during the recognition of body parts such as hands. One hypothesis is that different subpopulations of motor neurons in the frontal cortex are activated in each motor program; for example, canonical neurons in the premotor cortex are responsible for the affordance of visual objects, while mirror neurons support motor imagery triggered during handedness recognition. However, the question remains whether these subpopulations work independently. This hypothesis can be tested with a manual reaction time (MRT) task with a priming paradigm to evaluate whether the view of a manipulable object interferes with the motor imagery of the subject’s hand. The MRT provides a measure of the course of information processing in the brain and allows indirect evaluation of cognitive processes. Our results suggest that canonical and mirror neurons work together to create a motor plan involving hand movements to facilitate successful object manipulation.

Cognitive, Affective, & Behavioral Neuroscience, 2018

Previous work has shown that the perception of a graspable object may automatically potentiate actions that are tailored to specific action-related features of the object (e.g., its size) and may be related to its immediate grasping as well as to its long-term, functional use. We investigated the neural correlates of function-and size-related object affordances that may be concurrently potentiated by a graspable object. Participants were lying in a MR scanner holding a large switch in one hand and a small switch in the other hand. They passively attended a large or a small object with clearly separated functional and graspable end that was displayed centrally at an average angle of 45 degrees. Participants responded to the direction of an arrow that was overlaid on the object after a mean period of 1,000 ms after object onset and was pointing to the left or to the right with equal probability. Response times were shorter when the arrow pointed to the functional end of the object and when the responses were made with the switch that was congruent to the size of the perceived object. A clear distinction was found in the representation of functionand size-related affordances; the former was represented in the posterior parietal cortex and the latter in prefrontal, premotor, and primary sensorimotor cortices. We conclude that different aspects of object-directed actions may be automatically potentiated by individual object features and are represented in distinct brain areas.