ENHANCED VISUAL PROCESSING IN PERIHAND SPACE

1

Enhanced visual processing for objects in perihand space: Does it matter which hand acts
on the object or will any hand do?

Braydon Slack
UREAP Write Up

ENHANCED VISUAL PROCESSING IN PERIHAND SPACE

2

Abstract
Peri-hand space is described as the area immediately surrounding a person’s hands. This
area has been shown to lead to enhanced visual processing, demonstrated in studies involving a
visual search task. The functions of peri-hand space and its neurological development suggest
that it evolved to facilitate fine hand movements - this pilot study set out to investigate this. To
date, no research using a visual search task has had participants define peri-hand space and act
on target objects with the same hand; we hypothesized that this methodology would show greater
peri-hand space effects than when defining peri-hand space with one hand and acting on the
object with another hand. Our results showed that: 1) participants accurately identified
significantly more target objects with their non-dominant hand compared to their dominant hand,
2) participants found the target objects significantly faster when the object was graspable
compared to ungraspable, 3) when participant’s hands were near the screen they had a
significantly longer total fixation duration than when their hand was away from the screen, 4)
Participant’s target fixation duration was significantly shorter when using their dominant hand to
act on the object compared to their non-dominant hand, and 5) participants fixated on the target
for a significantly shorter amount of time when the object was graspable compared to nongraspable. These results partially support our hypothesis. This pilot study pioneered a novel way
to study peri-hand space and its effects. In the future, we will collect more participants (n=30) as
well as add extra conditions to minimize handedness effects.

ENHANCED VISUAL PROCESSING IN PERIHAND SPACE

3

Enhanced visual processing for objects in peri-hand space: Does it matter which hand
acts on the object or will any hand do?
The area immediately surrounding a person’s hand, known as peri-hand space, has been
shown to receive enhanced attentional focus compared to areas away from the hands. This
greater attentional focus also leads to greater object recognition and improved working memory
for objects in near-hand space (Reed, Grubb, & Steele, 2006; Adams et al., 2012; Du et al., 2017;
Tseng & Bridgeman, 2011). Research measuring late positive potentials (LPP)—which serve as
neural markers to record attention to emotional stimuli—revealed that participants show stronger
LPP’s when viewing unpleasant stimuli in near-hand space compared to viewing it away from
the hands (Dennis & Hajcak, 2009; Du et al., 2017). Together, the research surrounding perihand space suggests that it is evolutionarily advantageous; enhanced visual attention near the
hands allows people to be able to improve processing of unpleasant stimuli to avoid it, and
enhanced working memory allows for people to better recall hazardous stimuli that are in their
peri-hand space.
Peri-hand space effects on visual processing appear to be plastic and can adapt based on
people’s routines. Literature suggests that both left-handed and right-handed people are better at
detecting objects in right-hand space compared to left hand space; this has been attributed to
societal norms, such as door handles generally being on the right side of doors (Colman et al.,
2017). It was also found that participants have more accurate object discrimination near their
right hand compared to their left hand, which implies that there are visuomotor biases in the left
hemisphere of the brain, which controls the right hand (Colman et al., 2017). These handedness
effects likely emerged through repeated use of one hand over another during development,

ENHANCED VISUAL PROCESSING IN PERIHAND SPACE

4

leading to greater perihand space effects surrounding people’s dominant hands, thereby allowing
for more efficient object manipulation to occur with that hand.
In addition to handedness, a person’s hand postures appear to influence peri-hand space
effects. Literature has shown that open palmed grasp postures with the palms facing the objects
— known as collected hand postures — yield enhanced visual processing compared to pincer
posture grips (Thomas, 2013). Further evidence to support this comes from Dosso and Kingstone
(2018), which did not find peri-hand space effects when participants positioned their hands with
their palms perpendicular to the object on a screen but did so when their hands rested in a
collected posture on the screen. Participants also show greater attentional prioritization when
physical objects, such as tools, are placed near their palm compared to the back of their hands
(Reed et al., 2010). This likely occurs for two reasons. First, neurons with overlapping visual and
somatosensory receptive fields around the hands result in bimodal neurons firing more in the
parietal cortex when a visual stimuli is in peri-hand space (Kastner et al., 2017, Ladavas &
Serino, 2008). Second, there may be a top-down expectation to manipulate objects near the hand,
and you are more likely to manipulate an object with an open palm facing the objects than a
pincer grip or a hand posture in which the palms face away from the objects.
The neural processing of objects in peri-hand space appears to follow a separate pathway
than when objects are viewed away from the hands. Normally, visual information flows through
the geniculostriate pathway from the retina to the lateral geniculate body, to the primary visual
areas (V1, area V2, and then to area V5; Born & Bradley, 2005; Makin et al., 2012); however,
visual information near the hand appears to have evolved to take a more efficient route through
the brain, and seems to flow from the retina to the superior colliculus, to the pulvinar, bypassing
area V1 and V2 and going directly to area V5, through which flows to the ventral portion of the

ENHANCED VISUAL PROCESSING IN PERIHAND SPACE

5

intraparietal sulcus, where it then reaches the premotor cortex (Makin et al., 2012; Perry,
Amarasooriya, & Fallah, 2016; Rizzolatti & Matelli, 2003). This more efficient route of visual
processing for objects near the hands allows for crude visual information to integrate with
sensory information of hand position, which could enable more rapid actions with objects near
the hands (Makin et al., 2012).
Research has found that visual area V2 is involved in orientation selectivity when hands
are close to an object, which suggests that a feedback loops exists from reaching and grasping
networks in parietofrontal cortex back to the early cortical visual areas (Motter, 1993; Perry,
Sergio, Crawford, & Fallah, 2015). Evidence to support this assumption comes from participants
with blindness from an injury to the primary visual cortex—also known as cortical blindness.
Damage to the geniculostriate pathway prevents visual information from travelling to the cortical
visual areas. Therefore, participants with this injury should not be able to accurately process the
size of an object. However, research that has investigated these participants finds that when they
placed their hand near an object they were able to accurately estimate the target object using their
other hand, which suggests the visual information takes a separate route to get to the primary
visual areas enabling a unique phenomenon known as blindsight (Brown et al., 2008; Pellegrino
& Frassinetti, 2000; Schendel & Robertson, 2004).
A common way to study alterations in visual perception in peri-hand space involves
using a visual search task, in which participants look at a target image, then try to find that same
imagine in an array of distractor images with their hand either near the screen or away from the
screen (Le Bigot & Grosjean, 2016; Abrams & Weidler, 2014; Thomas, 2013). Using a visual
search task can yield measures such as search time—the time it takes for the participant to find
the target object, and accuracy—how many target objects participants correctly identified out of

ENHANCED VISUAL PROCESSING IN PERIHAND SPACE

6

the forty trials. This measure was used by Abrams et al. (2008) and is able to identify altered
visual processing near hands, as a slower shift in attention between items on the screen, which
suggests that more visual attention is given to each item on the screen. To date, previous
literature involving a visual search task has had one hand (generally the dominant hand) rest on
the side of the screen in a collected open palm posture with the palm facing the screen to test
peri-hand space. Although this method is sound, there is a troubling gap in the literature. If perihand space truly did evolve to facilitate fine hand movements with objects near the hands, then it
would make sense that using the same hand to both define peri-hand space and to act on the
object would yield greater near-hand space effects than using separate hands to define peri-hand
space and act on the object.
The current study aimed to close this gap in the research by requiring participants to use
their dominant hand to both define peri-hand space and to act on the object in the array to
determine whether this would yield greater peri-hand space effects than conventional methods.
Each participant completed a visual search task in which they had to find a target image from a
12-object visual array. The participant was to first find the object in the array and then reach out
and touch it as quickly as possible. Participants completed four conditions: dominant hand near
the screen and point to target, dominant hand far from the screen and point to target, dominant
hand near the screen and non-dominant hand point to target, dominant hand far from the screen
and non-dominant hand point to the target. When the participant’s hand was near the screen they
maintained a collected palm posture and their palms were directed towards the array of objects.
This allowed us to examine the effect of three independent variables in this study. First, the
variable of hand position was manipulated by positioning the participant’s dominant hand either
near the screen or in the participant’s lap. The second independent variable, acting hand, looked

ENHANCED VISUAL PROCESSING IN PERIHAND SPACE

7

at whether peri-hand space effects were stronger when participants used their dominant hand to
define peri-hand space, and another to touch the object on the screen, or when participants
established peri-hand space and acted on the object with the same hand. Finally, we presented
objects that were graspable and objects that were not graspable to examine the effects of object
graspability. There were three different dependent variables in this study: accuracy, the amount
of times participants correctly identified the target object out of the 40 trials; visual search time,
the amount of time it took participants to visually fixate on the target image after appearing in an
array of distractor images, and; target fixation duration, the amount of time participants visually
fixated on the target object before releasing their hand from the button. using a Positive Science
eye tracker, we examined participant’s visual attention, which included average pre-fixation
duration, target fixation duration, and number of fixations. We hypothesized that when
participants placed their dominant hand near the visual search array and used the same hand to
reach out and touch the target objects that they would show the greatest peri-hand space
effects—measured by a slower visual search time, greater accuracy, and shorter total fixation
duration—compared to all other conditions.
Participants
Adult participants were recruited from lower level psychology classes at Thompson
Rivers University (n =12). Participants ranged from 19 – 32 years old. Each participant had
normal or corrected to normal vision, and any participant with a sensory, motor, or
neurobiological disorder was excluded. Ethics approval was received in preparation for this pilot
study. Prior to the study beginning, participants signed an informed consent form and a photo
release form, as required by the Thompson Rivers University human ethics committee. Each

ENHANCED VISUAL PROCESSING IN PERIHAND SPACE

8

participant received a letter of information about the study to take home and received 2% credit
towards their Introduction to Psychology class for participating.
Materials and Apparatus
Visual Search Task
The current study used an E230t HP touch screen monitor to display a custom-made
visual search task. The visual search task was programmed using Unity game engine and was
coded in Visual Studio which used C# programming language. An external button from P.I.
Engineering was connected to the computer via USB and either rested on the right-hand side of
the computer screen or on the participant’s right thigh, depending on the condition. Pressing and
holding the button resulted in a fixation cross appearing on the center of the screen for 1 second
— this cross would disappear and then a single target object would appear for 2 seconds.
Following this, a visual array appeared which contained 11 distractor objects and 1 target object,
which was the same as the previously displayed object. There were 8 different visual arrays,
made up of 4 non-graspable arrays (horses, houses, cars, people) and 4 graspable arrays (fruits,
toys, tools, balls). The computer program recorded 5 measures: the time from when the visual
search array appeared to when the button was released; the time from when the button was
released to when the participant touched the screen with their finger; whether the touch on the
screen matched the location of the target; precision of the touch on the target; and total time
required to complete the task. The order in which the location of the objects appeared on the
array, and the order in which the arrays appeared were randomized and counterbalanced. Also,
each array was not presented more than 5 times per 40 trials. The two center spots in the array
never contained the target location because it was too close to where the viewer was looking
before the array appeared. The location of the target in the array was randomized so each target

ENHANCED VISUAL PROCESSING IN PERIHAND SPACE

9

location did not occur more than 4 times per 40 trials, and the target image was randomized with
a limit so that each target object would only ever appear once within the 40 trials.
Eye Tacking System
The experiment used eye tracking software by Positive Science. LiveCapture software
tracked participant eye movements during the visual search task. The eye tracking video was
calibrated offline after the participants left the lab using the program Yarbus to create a rendered
video that showed where participants looked during the visual search task.
Procedure
Each participant signed an informed consent form and a photo release form when they
entered the lab. Then, the participant was instructed on how to complete a visual search task
using a script describing the task and was fitted with a head mounted eye tracker. They sat facing
a touch screen monitor with both their hands on their lap. The touchscreen monitor was adjusted
to the participant’s eye level, and the button was either placed on the right side of the touch
screen monitor or in the participant’s lap, depending on the condition.
The participant’s information was entered into the custom software, then participants
completed a training condition to practice the visual search task and ensure they understood how
to complete the task. Participants had to successfully complete 5 training trials before beginning
the task. Before beginning the task, the participants either put their dominant hand on the button
on the screen in a collected hand posture with their palms facing the screen, and their nondominant hand in their lap or put both their hands in their lap with either their dominant or nondominant hand resting on the button on their corresponding upper thigh. The order of conditions
was partially counterbalanced using a Latin Square design. Once the participant was in position
to begin the study, they pressed the button with their hand and held the button down. After

ENHANCED VISUAL PROCESSING IN PERIHAND SPACE

10

holding down the button the trial was initiated, and the participant was required to look for the
target image in an array of distractor images. Once the participant found the target object, they
released the button and either touched it with their dominant or non-dominant hand using their
index finger, depending on the condition. After the participant touched the object, the screen
went blank and the participant pressed and held the button again to begin the next trial. At the
end of 40 trials, the computer screen would read “Thank you for completing this testing session”.
The participant would get into position to begin the next condition and completed 40 trials under
the new condition until all four conditions were complete.
When all conditions were complete the data was saved and the eye tracker was removed
from the participant. The participant was given a debriefing form, which explained our
hypothesis, and they were offered a Human Ethics Feedback Form and were told they could
complete it if they would like to. Finally, participants were given a copy of the Letter of
Information to take with them.
Data Analysis
This study used a 2x2x2 within subjects design. Hand position (dominant hand close vs.
far from the screen), acting hand (dominant vs. non-dominant hand touching the screen), and
object type (Graspable vs. Non-graspable) were the independent within-subjects variables. The
dependent variables were: accuracy, which was defined as how many targets participants
correctly identified out of the 40 trials; visual search time, which was how long it took for
participants to visually fixate on the target image, and; total fixation duration, which was defined
as how long the participant visually fixated on the target image before releasing their hand from
the button. Accuracy was calculated by dividing the number of correct trials with the number of
incorrect trials for each condition. Visual search time was calculated as the difference between

ENHANCED VISUAL PROCESSING IN PERIHAND SPACE

11

the frame number of when the array appeared and the frame number in which the participants
visually fixated on the target object. To calculate total fixation duration, we took the frame
number that the participants visually fixated on the target object and the frame number that the
participant released their hand from the button.
Following data collection, the participants rendered videos were analyzed frame-byframe using Kinovea software. Frame numbers were recorded for the time that the array fully
appeared (when the images were fully contrasted on the screen), the frame number that
participants visually fixated on the target object, and the frame number in which the participants
touched the target object (defined as the frame number when the images completely faded from
the screen). The frame numbers were input into an Excel spreadsheet containing additional
measures recorded from the custom visual search task software to be analyzed. The raw scores
were converted to mean scores for each dependent variable. The data was then analyzed in
separate repeated measures analyses of variance (ANOVAs) via the program SPSS.
Results
This study made use of a repeated measures ANOVA to examine the effect of hand
position, acting hand, and object graspability on accuracy, visual search time, and target fixation
duration in a visual search task. Participant trials were excluded for the following reasons: the
participant released their hand before fixating on the target image, the participant blinked
between locating the target image and releasing their hand to touch the object, the eye tracker
had a calibration issue, or the participant incorrectly identified the target image.
Accuracy
Accuracy was defined as the proportion of total trials that the participants correctly
identified the target image. The statistical analysis revealed that here was no significant effect of

ENHANCED VISUAL PROCESSING IN PERIHAND SPACE

12

hand position on accuracy F (1, 11) = 1.59, p = n.s There was a significant effect of acting hand
on accuracy F (1, 11) = 13.10, p = 0.004 ηp2= 0.54, in that participants were significantly more
accurate when they touched the target with their non-dominant hand compared to their dominant
hand (Figure 1). There was no significant effect of graspability F (1, 11) = 0.40, p = n.s. There
were no significant interactions between hand position and acting hand F (1, 11) = 0.07, p = n.s.,
hand position and graspability F (1, 11) = 0.61, p = n.s., acting hand and graspability F (1, 11) =
0.51, p = n.s., or hand position, acting hand, and graspability on accuracy F (1, 11) = 0.81, p =
n.s. Thus, when participants used their non-dominant hand to act on the target object they were
significantly more accurate than when using their dominant hand to act on the target object
regardless of whether their dominant hand was positioned near or far from the array.
Visual Search Time
Visual search time refers to the amount of time it took the participant to visually fixate on
the target object after it appeared in an array of distractor objects. There was not a significant
effect of hand position on visual search time F (1, 11) = 0.93, p = n.s. There was, however, a
significant effect of graspability on visual search time F (1, 11) = 133.04, p = > 0.001, ηp2 =0.92.
Participants had a significantly faster visual search time when the objects were graspable
compared to ungraspable (Figure 2). There was not a significant effect of acting hand F (1, 11) =
0.001, p = n.s. No significant interactions were found for hand position and acting hand F (1,11)
= 2.49, p = n.s., hand position and graspability F (1, 11) = 0.41, p = n.s., acting hand and
graspability F (1, 11) = 0.004, p = n.s., or hand position, acting hand, graspability on visual
search time F (1, 11) = 1.02, p = n.s. Thus, when the target object was graspable participants
identified the target object significantly faster compared to when the target object was non-

ENHANCED VISUAL PROCESSING IN PERIHAND SPACE

13

graspable regardless of which hand acted on the object and regardless of whether the dominant
hand was positioned near or far from the screen.
Total Fixation Duration
Total fixation duration was defined as the time from when the participant visually fixated
on the target object to when they released their hand from the button. There was a significant
effect of hand position on target fixation duration F (1, 11) = 5.41, p = 0.04, ηp2 = 0.33.
Participants had a significantly longer target fixation duration when their hand was near the
screen compared to away from the screen (Figure 3). A significant effect of acting hand on
target fixation duration was found F (1, 11) = 16.76, p = 0.002, ηp2 = 0.60 in that participants had
a significantly shorter total fixation duration when using their dominant hand to act on the object
compared to their non-dominant hand (Figure 4). There was also a significant effect of
graspablility on total fixation duration F (1, 11) = 42.85, p = <0.001, ηp2 = 0.80. Participants had
a significantly shorter target fixation duration when the object was graspable compared to nongraspable (Figure 5). No significant interactions were found for hand position and acting hand F
(1, 11) = 0.55, p = n.s., hand position and graspability F (1, 11) = 3.95, p = n.s., acting hand and
graspability, F (1, 11) = 1.83, p = n.s., or acting hand, hand position, and graspability F (1, 11) =
0.01, p = n.s. When the participant’s hand was near the screen they fixated on the target object
for longer before releasing the button compared to when their hand was far from the screen.
Participants fixated on the target image for less time when using their dominant hand to act on
the image compared to their non-dominant hand. Lastly, when the target object was graspable,
participants fixated on the target image for less time before acting on it compared to when the
target image was non-graspable.

ENHANCED VISUAL PROCESSING IN PERIHAND SPACE

14

Discussion
This pilot study set out to investigate a novel way to study perihand space in which
participants used the same hand to both define peri-hand space and act on the object on the
screen. This method was based off of the idea that peri-hand space evolved to facilitate fine hand
movements. Therefore, it makes sense that using the same hand to define peri-hand space and act
on the object would yield greater peri-hand space effects compared to traditional methods used in
a visual search task. To do this, participants wore an eye tracker and completed a visual search
task under four conditions: dominant hand near the computer and acting on the object, dominant
hand far and acting on the objects, dominant hand near and opposite hand acting on the objects,
dominant hand far and opposite hand acting on the object. In all hands close conditions, the
participant rested their dominant hand on the right side of the monitor in a collected hand posture
with their palm facing the screen. We hypothesized that when participants placed their dominant
hand near the visual search array and used the same hand to reach out and act on the target object
in the visual array that they would show the greatest peri-hand space effects— greater accuracy,
slower visual search time, and shorter target fixation duration—compared to all other conditions.
Based on findings from Colman et al. (2017) we also predicted that participants would show
greater peri-hand space effects when the target object was graspable compared to non-graspable.
Our results partially support our hypothesis.
A number of sophisticated techniques were used to analyze peri-hand space effects in
human adults. First, a visual search task was used to investigated peri-hand space because it is a
reliable task for studying peri-hand space and has been used previously (Le Bigot & Grosjean,
2016; Abrams & Weidler, 2014; Thomas, 2013). Second for the hands close conditions,
participants maintained an open palmed, collected hand posture, as this position has been shown

ENHANCED VISUAL PROCESSING IN PERIHAND SPACE

15

to yield enhanced peri-hand space effects compared to other hand postures (Thomas, 2013;
Dosso & Kingstone, 2018). This previous literature served as the foundation of our methodology
in hopes of producing noticeable peri-hand space effects in participants.
Even though our pilot study used previous literature as a rationale for our methods,
limitations still existed in this research. First, this research had twelve participants, and the power
of the findings were low. Future research will need to address this issue by recruiting more
participants to increase the power and replicability of the results. In addition to this, a confound
is present. In this study, participants are acting on the object with their dominant and nondominant hands. Previous literature has found that participants show enhanced peri-hand space
effects for their dominant hand compared to their non-dominant hand (Colman et al., 2017;
Laura Elizabeth Thomas, 2013; Le Bigot, Grosjean, & De Lange, 2012). Because of this, it is
difficult to discern if our results are due to enhanced peri-hand space effects or a result of
participants using their dominant hand to act on the object. Future research will address this
confound by adding two more conditions: Non-dominant hand near the screen + act on the
object; non-dominant hand near the screen + dominant hand act on the object. These two extra
conditions will help rule out any handedness confounds.
Our measure of accuracy was defined as how many times participants correctly identified
the target image out of forty trials. Previous literature suggests that participants are more
accurate when identifying objects near the hands compared to objects away from the hands
(Thomas, 2013). In addition to this, past research has found that participants show more accurate
object discrimination near their right hand compared to their left hand (Colman et al, 2017).
Therefore, we hypothesized that participants would show the greatest peri-hand space effects
when using their dominant hand to both define peri-hand space and act on the target object. After

ENHANCED VISUAL PROCESSING IN PERIHAND SPACE

16

analysis, our data showed a significant effect of acting hand on accuracy—participants were
significantly more accurate when they touched the target object with their non-dominant hand
compared to their dominant hand. This finding is surprising, because it opposes an abundance of
previous literature suggesting that peri-hand space effects are greater when participants used
their dominant hand to define peri-hand space compared to when they used their dominant hand
(Colman et al., 2017; Laura Elizabeth Thomas, 2013; Le Bigot, Grosjean, & De Lange, 2012).
These results may have been obtained due to the small sample size; with only twelve
participants, it is hard to fully interpret the results. Before these results can bear any weight, data
collection with more participants is necessary.
Our measure of visual search time refers to the amount of time participants took to find
the target object after it appears in an array of distractor objects. Previous research by Abrams et
al. (2008) found that participants showed greater peri-hand space effects—denoted by a slower
shift in attention between the objects on the screen—when their hand was near the screen
compared to away from the screen. Therefore, we predicted that participants would show a
slower shift in attention between the objects when using the same hand to define peri-hand space
and act on the object, compared to using one hand to define peri-hand space and another to act
on the object. We did not find this, but we did find a significant main effect of graspability;
participants were significantly faster at identifying a target object in an array of distractor objects
when the target was graspable compared to non-graspable. These results are similar to findings
by Colman et al. (2017) showing that peri-hand space effects are more pronounced when the
target object is graspable compared to non-graspable.
Total fixation duration was defined as the amount of time from when the participants
fixated on the target object to when they released their hand from the button in order to reach out

ENHANCED VISUAL PROCESSING IN PERIHAND SPACE

17

and touch the object. Past literature has shown that participants have faster object recognition
times when their hand is near the object compared to away from the object (Adams et al., 2012;
Reed, Grubb, & Steele, 2006). Because of this, we hypothesized that participants would have a
faster object recognition time—target fixation duration—when using the same hand to define
peri-hand space and act on the target object. Participants had a significantly shorter total fixation
duration when the object was graspable compared to non-graspable. Further, our results also
demonstrated that participants had a significantly shorter target fixation duration when using
their dominant hand to act on the target object compared to using their non-dominant hand to act
on the object; concurring with previous literature (Colman et al., 2017; Laura Elizabeth Thomas,
2013; Le Bigot, Grosjean, & De Lange, 2012). However, due to a confound of handedness
effects, the significant effect of acting hand on total fixation duration may be a result of
participants simply being more well adapted with their dominant hand compared to their nondominant hand. Future research will need to incorporate extra conditions to address the potential
handedness confound.
Surprisingly, our findings show a significantly longer target fixation when the
participant’s hand was near the screen compared to away from the screen, which is the opposite
of what is expected in peri-hand space. This may be due to a trending interaction between hand
position and graspability. When the objects were non-graspable participants had a substantially
longer target fixation duration in the hands close condition compared to the hands far condition;
when the objects were graspable, there was only a slight difference in target fixation duration
between the hands close and hands far conditions (Figure 6). This may be because ungraspable
objects could bias visual processing towards the ventral (parvocellular) pathways, whereas the
graspable objects may bias visual processing towards the dorsal (magnocellular) pathways. The

ENHANCED VISUAL PROCESSING IN PERIHAND SPACE

18

magnocellular pathway has also been shown to be involved in “gist” or fast processing of
images, which may explain why the graspable objects produce notably faster target fixation
duration times than the ungraspable objects, which would not have “gist” processing (Chan,
Peterson, Barense, & Pratt, 2013). Because the magnocellular pathway—which is involved in
gist processing—and the parvocellular pathway—involved in more detailed processing—inhibit
each other, the large discrepancy between non-graspable objects and graspable objects may be
because “gist” processing was unavailable for non-graspable objects, leading to a significantly
longer target fixation duration time, and influencing the main effect of hand position (Yeshurun
& Levy, 2003).
Conclusion and Recommendations
To conclude, this pilot study set out to test a novel way to study peri-hand space. If perihand space did in fact evolve to facilitate fine hand movements, then it would make sense that
using the same hand to define peri-hand space and act on the object would yield greater nearhand effects than using one hand to define the space and another hand to act on objects in that
space. Our results revealed that participants were significantly faster at identifying a target object
in an array of distractor objects when the target was graspable compared to non-graspable, which
supported our hypothesis and previous literature by Colman et al. (2017). Nonetheless, contrary
to our hypothesis, participant’s showed lower accuracy and shorter target fixation duration when
using their dominant hand to identify the target object in the array. However, it is important to
acknowledge the limitations and confounds present in this pilot study; at only twelve participants
it is hard to confidently conclude our significant results and accept our non-significant outcomes.
Further investigation with more participants will be necessary to conclude whether or not this
new method of studying peri-hand space is effective or not. In addition to this, adding the

ENHANCED VISUAL PROCESSING IN PERIHAND SPACE

19

following two conditions will help rule out if the acting hand effects found were a result of using
the same hand for peri-hand space and acting on the object, or if the effects were because the
participants were using their dominant hand: non-dominant hand near the array + point to target,
non-dominant hand near array + dominant hand point to target.

ENHANCED VISUAL PROCESSING IN PERIHAND SPACE

20

References
Abrams, R. A., Davoli, C. C., Du, F., Knapp, I. H., & Paull, D. (2008). Brief article: Altered
vision near the hands. Cognition, 107, 1035-1047. doi:10.1016/j.cognition.2007.09.006
Adams, J. J., Bovend’Eerdt, T. J. H., van Dooren, F. E. P., Fischer, M. H., & Pratt, J. (2012). The
closer the better: Hand proximity dynamically affects letter recognition
accuracy. Attention Perception & Psychophysics, 74(7), 1533–1538. https://doiorg.ezproxy.tru.ca/10.3758/s13414-012-0339-3
Abrams, R. A., & Weidler, B. J. (2014). Trade-offs in visual processing for stimuli near the
hands. Attention, Perception, & Psychophysics, 76(2), 383–390. https://doiorg.ezproxy.tru.ca/10.3758/s13414-013-0583-1
Adams, J. J., Bovend’Eerdt, T. J. H., van Dooren, F. E. P., Fischer, M. H., & Pratt, J. (2012). The
closer the better: Hand proximity dynamically affects letter recognition
accuracy. Attention Perception & Psychophysics, 74(7), 1533–1538. https://doiorg.ezproxy.tru.ca/10.3758/s13414-012-0339-3
Born, R. T., & Bradley, D. C. (2005). Structure and function of visual area MT. Annual Review
of Neuroscience, 28, 157–189. Retrieved from
https://ezproxy.tru.ca/login?url=https://search-ebscohostcom.ezproxy.tru.ca/login.aspx?direct=true&db=mnh&AN=16022593&site=eds-live
Brown, L. E., Kroliczak, G., Demonet, J.-F., & Goodale, M. A. (2008). A hand in blindsight:
Hand placement near target improves size perception in the blind visual
field. Neuropsychologia, 46, 786–802. https://doiorg.ezproxy.tru.ca/10.1016/j.neuropsychologia.2007.10.006

ENHANCED VISUAL PROCESSING IN PERIHAND SPACE

21

Chan, D., Peterson, M., Barense, M., & Pratt., J. (2013). How action influences object
perception. Frontiers in Psychology. https://doi.org/10.3389/fpsyg.2013.00462
Colman, H. A., Remington, R. W., & Kritikos, A. (2017). Handedness and graspability modify
shifts of visuospatial attention to near-hand objects. PLoS ONE, 12(1), 1–19.
https://doi-org.ezproxy.tru.ca/10.1371/journal.pone.0170542
Dennis, T. A., & Hajcak, G. (2009). The late positive potential: A neurophysiological marker for
emotion regulation in children. Journal of Child Psychology & Psychiatry, 50(11), 1373–
1383. https://doi-org.ezproxy.tru.ca/10.1111/j.1469-7610.2009.02168.x
Dosso, J. A., & Kingstone, A. (2018). The fragility of the near-hand effect. Collabra:
Psychology, (1). https://doi.org/10.1525/collabra.167
Du, F., Wang, X., Abrams, R. A., & Zhang, K. (2017). Original articles: Emotional processing
is enhanced in peri-hand space. Cognition, 165, 39–44. https://doiorg.ezproxy.tru.ca/10.1016/j.cognition.2017.04.009
Jill A. Dosso, & Alan Kingstone. (2018). The fragility of the near-hand effect. Collabra:
Psychology, (1). https://doi.org/10.1525/collabra.167
Kastner, S., Chen, Q., Jeong, S., & Mruczek, R. (2017). A brief comparative review of primate
posterior parietal cortex: A novel hypothesis on the human
toolmaker. Neuropsychologia, 105, 123-134.
doi:10.1016/j.neuropsychologia.2017.01.034
Ladavas, E., & Serino, A. (2008). Action-dependent plasticity in peripersonal space
representations. Cognitive Neuropsychology, 25(7-8), 1099-1113.
Laura Elizabeth Thomas. (2013). Grasp posture modulates attentional prioritization of space near
the hands. Frontiers in Psychology. https://doi.org/10.3389/fpsyg.2013.00312

ENHANCED VISUAL PROCESSING IN PERIHAND SPACE

22

Le Bigot, N., Grosjean, M., & De Lange, F. P. (2012). Effects of handedness on visual sensitivity
in peri-hand Space. Plos ONE, 7(8), 1-6. doi:10.1371/journal.pone.0043150
Le Bigot, N., & Grosjean, M. (2016). Exogenous and endogenous shifts of attention in perihand
space. Psychological Research, 80(4), 677–684. https://doi.org/10.1007/s00426-0150680-y
Makin, T. R., Holmes, N. P., Brozzoli, C., & Farnè, A. (2012). Keeping the world at hand: Rapid
visuomotor processing for hand-object interactions. Experimental Brain
Research, 219(4), 421–428. https://doi-org.ezproxy.tru.ca/10.1007/s00221-012-3089-5
Motter, B. C. (1993). Focal attention produces spatially selective processing in visual cortical
areas V1, V2, and V4 in the presence of competing stimuli. Journal of Neurophysiology,
70(3), 909-919. Doi: 10.1152/jn.1993.70.3.909
Pellegrino G, & Frassinetti, F. (2000). Direct evidence from parietal extinction of enhancement
of visual attention near a visible hand. Current Biology: CB, 10(22), 1475–1477.
Retrieved from
https://search.ebscohost.com/login.aspx?direct=true&db=mnh&AN=11102814&site=eds
-live
Perry, C. J., Sergio, L. E., Crawford, J. D., & Fallah, M. (2015). Hand placement near the visual
stimulus improves orientation selectivity in V2 neurons. Journal of
Neurophysiology, 113(7), 2859-2870. doi:10.1152/jn.00919.2013 Brown, L. E.,
Perry, C. J., Amarasooriya, P., & Fallah, M. (2016). An eye in the palm of your hand: Alterations
in visual processing near the hand, a mini-review. Frontiers in Computational
Neuroscience, 10. doi:10.3389/fncom.2016.00037/full

ENHANCED VISUAL PROCESSING IN PERIHAND SPACE

23

Reed, C. L., Betz, R., Garza, J. P., & Roberts, R. J., Jr. (2010). Grab it! Biased attention in
functional hand and tool space. Attention Perception & Psychophysics, 72(1), 236–245.
https://doi-org.ezproxy.tru.ca/10.3758/APP.72.1.236
Reed, C. L., Grubb, J. D., & Steele, C. (2006). Hands up: Attentional prioritization of space near
the hand. Journal of Experimental Psychology. Human Perception &
Performance, 32(1), 166-177. doi:10.1037/0096-1523.32.1.166
Rizzolatti, G., & Matelli, M. (2003). Two different streams form the dorsal visual system:
Anatomy and functions. Experimental Brain Research, 153(2), 146–157. Retrieved from
https://ezproxy.tru.ca/login?url=https://search.ebscohost.com/login.aspx?direct=true&
db=mnh&AN=14610633&site=eds-live
Schendel, K., & Robertson, L. C. (2004). Reaching out to see: arm position can attenuate human
visual loss. Journal Of Cognitive Neuroscience, 16(6), 935–943. Retrieved from
https://search.ebscohost.com/login.aspx?direct=true&db=mnh&AN=15298781&site=eds
-live
Thomas, L. (2013). Grasp posture modulates attentional prioritization of space near the
hands. Frontiers in Psychology, 4. https://doiorg.ezproxy.tru.ca/10.3389/fpsyg.2013.00312/full
Tseng, P., & Bridgeman, B. (2011). Improved change detection with nearby hands. Experimental
Brain Research, 209(2), 257–269. https://doi-org.ezproxy.tru.ca/10.1007/s00221-0112544-z

ENHANCED VISUAL PROCESSING IN PERIHAND SPACE

24

Yeshurun, Y., & Levy, L., (2003). Transient spatial attention degrades temporal
resolution. Psychological Science, 14(3), 225. Retrieved from
https://search.ebscohost.com/login.aspx?direct=true&db=edsjsr&AN=edsjsr.40063893&s
ite=eds-live

ENHANCED VISUAL PROCESSING IN PERIHAND SPACE

25

Effect of Acting Hand on Accuracy
0.990
0.980
0.970
0.960
0.950
0.940
0.930
0.920
Dominant Hand
Graspable

Non-Dominant Hand
Ungraspable

Figure 1. Participants’ effect of acting hand on accuracy for graspable and non-graspable objects

ENHANCED VISUAL PROCESSING IN PERIHAND SPACE

Effect of Graspability on Visual Search Time
1.600
1.500
1.400
1.300
1.200
1.100
1.000
0.900
0.800
0.700
0.600
Graspable

Ungraspable
Hands Close

Hands Far

Figure 2. Effect of graspability on visual search time for graspable and non-graspable objects

26

ENHANCED VISUAL PROCESSING IN PERIHAND SPACE

Effect of Hand Position on Total Fixation Duration
0.600
0.580
0.560
0.540
0.520
0.500
0.480
0.460
0.440
0.420
0.400
Hands Close
Graspable

Hands Far
Ungraspable

Figure 3. Effect of Hand position on total fixation duration for graspable and non-graspable
objects

27

ENHANCED VISUAL PROCESSING IN PERIHAND SPACE

28

Effect of Acting Hand on Total Fixation Duration
0.650
0.600
0.550
0.500
0.450
0.400
0.350
Dominant Hand
Graspable

Non-Dominant Hand
Ungraspable

Figure 4. Effect of acting hand on total fixation duration for graspable and non-graspable objects

ENHANCED VISUAL PROCESSING IN PERIHAND SPACE

29

Effect of Graspability on Total Fixation Duration
0.600
0.580
0.560
0.540
0.520
0.500
0.480
0.460
0.440
Hands Close
Graspable

Hands Far
Ungraspable

Figure 5. Effect of graspability on total fixation duration for graspable and non-graspable objects

ENHANCED VISUAL PROCESSING IN PERIHAND SPACE

Interaction Between Hand Position and
Graspability on Total Fixation Duration
0.585
0.565
0.545
0.525
0.505
0.485
0.465
Hands Close
Graspable

Hands Far
Ungraspable

Figure 6. Interaction between hand position and graspability on total fixation duration.

30