Perception In Sport

Perception In Sport sports psychologyPerception  brings  us  into  contact  with  people, objects,   and   places   within   the   environment. Perception  relies  on  sensory  systems  that  enable humans  to  see,  hear,  feel,  smell,  and  taste.  It  is estimated  that  one  third  of  the  human  brain  is dedicated to perception. Early Greek philosophers were  among  the  first  to  study  the  science  of  perception. Their strong bias toward sight continues to this day, and sport psychology (SP) is no exception.  For  example,  in  addition  to  the  wide  body of  research  that  has  studied  the  motor  dexterity of elite athletes, a growing number of researchers have  studied  the  visual  perceptual  skills  of  these athletes.  Visual  perception  is  critical  for  decision making (DM); for example, to recognize an opponent’s pattern of play to assume a strategically apt position for intercepting the ball and for the guidance of action, when for instance, controlling running  speed  and  direction  in  order  to  successfully catch  a  fly  ball.  This  entry  addresses  perception by providing an overview of the physiology of the visual  system  and  the  two  dominant  theoretical approaches used to study perception: information processing and ecological psychology. In line with the typically predominant interest in visual perception, this entry uses the term perception to refer to visual perception, except where stated otherwise.

Physiology of the Visual System

Visual perception starts with rays of light, or stimulus  information,  falling  upon  the  retina  at  the back  of  the  eye.  The  retina  consists  of  different types of light sensitive photoreceptors colloquially named rods and cones. The rods greatly outnumber the cones and are distributed across the entire retina  except  at  the  fovea,  the  location  of  highest  visual  resolution,  where  the  cones  are  highly concentrated. The rods are more sensitive to light than  cones  and  are  involved  in  the  perception  of location  and  motion.  Rods  only  provide  coarse perception  of  the  environment  (i.e.,  low  acuity). The  cones  function  best  in  bright  light;  they  are important  for  perceiving  detail  (i.e.,  high  acuity) and color. The stimuli at the retina are relayed to the brain along the optic nerve, which consists of different  populations  of  ganglions  cells  that  project  onto  the  lateral  geniculate  nucleus  and  from there to the primary visual cortex (V1) at the rear of the brain. Magnocellular ganglion cells are fast and transport stimulus information important for the perception of motion and location or distance. Parvocellular  ganglion  cells  are  much  slower  and transfer  stimulus  information  about  color  and edges (i.e., shape). A third population of ganglion cells project directly to the subcortical areas of the visual system (i.e., the superior colliculus) to facilitate the control of eye movements. From the primary visual cortex, stimulus information is further distributed to higher cortical areas, each of which selectively  processes  different  visual  properties. For example, V2 (and V1) process orientation, V3 supports shape perception, V4 is involved in color perception, and V5 or MT is dedicated to motion perception.  Importantly,  beyond  V1  the  visual brain is organized into two distinct pathways, one toward  the  parietal  lobe  (the  dorsal  stream)  and the  other  toward  the  temporal  lobe  (the  ventral stream). There is fierce debate over the respective functions of the two visual systems. Traditionally, the  systems  have  been  distinguished  in  terms  of their input: The dorsal stream is referred to as the where  stream  reflecting  its  primary  function  for spatial  perception  (i.e.,  the  perception  of  motion, distance, and location), whereas the ventral stream is named the what stream consistent with the supposition  that  it  is  responsible  for  object  perception (i.e., the perception of shape, size, and color). However,   a   relatively   recent   reinterpretation emphasizes  the  distinctive  functions  of  the  two streams rather than their input. Hence, the dorsal stream is proposed to be the action stream, underpinning the fast, unconscious, and online control of movement, while the ventral stream is the perception stream, a relatively slow but mostly conscious system  surmising  knowledge  about  the  environment.  This  distinction  between  action  and  perception  is  particularly  relevant  when  considering perception in sport.

Information-Processing Approach to Perception

In  SP,  as  in  most  other  domains  of  psychology, information-processing approaches have undoubtedly been the dominant theory for understanding perception.  Information-processing  approaches consider  human  perception  to  act  in  a  manner similar  to  a  digital  computer.  In  this  metaphor, the  visual  system  is  considered  to  be  the  “hardware”  that  underlies  perception.  Yet,  the  most distinctive  feature  of  these  approaches  for  understanding  perception  is  the  “software”  conceived to  be  necessary  for  the  different  stages  of  information  processing.  In  one  of  the  earliest  encompassing  accounts  of  the  information  processing approach in SP, H. T. A. Whiting distinguished a series of successive and separate stages of information  processing:  the  input,  decision-making,  and output stages. In the input stage, the eyes register stimulus  information  from  the  environment  and transmit it to the brain. Importantly, the transmission of information is selective; because of the vast amount of stimuli, it is not possible to attend to all the  stimulus  information  that  is  available  at  any one time.

The  stimulus  information  in  itself  is  inherently ambiguous.  For  example,  the  retinal  size  of  an object  varies  according  to  the  distance  between the object and observer, and retinal shape varies as function of the orientation of the object relative to the observer. A single object can therefore generate an infinite number of different stimulus patterns on the retina and hence is considered to be insufficient as a basis for perception. The stimulus information needs to be interpreted or enriched. Consequently, in the decision-making stage of processing, central mechanisms in the brain must interpret and process the stimulus information to form a representation of the environment. These internal representations then  provide  the  basis  for  other  central  mechanisms  that  make  decisions  about  a  new  action, or  adjustments  in  an  ongoing  action,  to  program appropriate movement responses. In the final output  stage,  the  programmed  movement  responses are  performed  by  the  musculoskeletal  system. Notably,  for  information-processing  approaches, perception ends the instant that an internal perceptual  representation  of  the  environment  has  been created.  For  this  reason,  within  the  information processing  approach,  perception  and  action  are conceived  as  largely  independent  processes  that can be studied in isolation from one another.

Information-Processing Approach in Sport Research

In   sport   research,   the   information-processing approaches  have  above  all  been  used  to  better understand  perception  and  perceptual  expertise in  DM  and  anticipation.  In  this  respect,  a  common  feature  for  perception  in  sport  is  that  it  is performed  under  restrictive  time  constraints—for example, when attempting to interrupt the opponents’  attacking  play  and  passing  the  intercepted ball  to  a  teammate.  Hence,  successful  performance  requires  perception  or  anticipation  of  the outcome of others’ actions before it is fully manifested  in  ball  flight:  a  player  is  often  too  late  if he  or  she  waits  until  the  outcome  information  is available. Early investigations, predating the information processing approach, assumed that expert performers  must  possess  visual  hardware  that  is better  than  in  lesser-skilled  performers  (i.e.,  better visual acuity [VA], color perception, or peripheral vision). On the whole, this research failed to demonstrate  a  strong  relationship  between  sport skill  and  the  low-level  physiological  properties. Yet,  given  the  recent  dramatic  improvement  in our  understanding  of  the  visual  brain,  it  may  be premature  to  completely  discard  this  proposal. For instance, measures like motion and speed perception,  which  purportedly  reflect  processing  of higher  cortical  areas,  may  or  may  not  eventually prove  to  distinguish  athletes  with  different  levels of skill.

More  recent  evidence  has  shown  that  experts possess  a  superior  sport-specific  knowledge  base in addition to a superior ability to process stimulus information. These capacities speak to the very heart  of  the  information-processing  approach, which holds that the inherently insufficient information  in  the  stimulus  needs  to  be  enriched  for perception  to  become  meaningful—that  is  to say,  to  form  a  high-fidelity  representation  of  the environment.  This  enrichment  comes  about  by relating  the  stimulus  to  task-specific  knowledge built  from  past  experiences  via  the  processes  of encoding  (i.e.,  transforming  stimulus  information  into  a  neural  code  that  can  be  stored  in  the knowledge  base)  and  retrieval  (i.e.,  the  reverse process whereby stored perception information is accessed).  Perception  is  more  truthful  and  rapid when  the  knowledge  base  becomes  wider  and when  encoding  and  retrieval  become  more  efficient. Indeed, experts are shown to recognize and recall patterns of play more accurately and much quicker  than  lesser-skilled  players.  In  a  seminal study,  Adriaan  D.  de  Groot  briefly  presented images  of  chess  positions  to  players  of  different skill  levels  and  asked  them  to  reconstruct  the positions.  The  expert  chess  players  were  able  to recall  the  positions  with  relatively  few  mistakes, whereas players below master level made a large number  of  errors.  When  players  in  a  subsequent study  viewed  both  structured  (i.e.,  real)  and unstructured  (sometimes  impossible)  chess  positions, the recall of the experts was found only for the  real  configurations.  This  demonstrates  that skilled  players  possess  more  efficient  game-specific  encoding  and/or  retrieval  of  chess  positions rather  than  exceptional  visual  memory  or  speed of  processing.  The  expert  players  reproduce  the positions by grouping together or chunking small groups of individual pieces into larger meaningful units. This chunking allows the experts to process more  information  while  using  the  same  (limited) memory capacity.

The  superior  encoding  and  retrieval  shown  by experts in a static game like chess have been shown to  also  exist  in  more  dynamic  sports  like  basketball, field hockey, and soccer. Typically, this work presents  high and  low-skilled  players  with  pictures or video clips of structured and unstructured patterns  of  play.  Superior  recognition  and  recall is  commonly  observed  among  high-skilled  players,  suggesting  that  expertise  entails  an  enhanced ability  to  perceptually  chunk  the  observation  of individual  players  into  larger  (meaningful)  units. Presumably, this allows these athletes to anticipate the outcome of patterns of play earlier, and more accurately, than lower-skilled players.

Indeed,  studies  employing  the  temporal  occlusion  paradigm  have  provided  ample  evidence that  high-skilled  players  anticipate  action  outcomes by extracting early, pre-ball flight stimulus information  (or  advance  cues).  In  the  temporal occlusion paradigm, participants view video clips simulating an athlete’s view of an evolving pattern of play (e.g., an offensive move by a team) or an opponent’s  action  (e.g.,  a  badminton  serve).  The clips  are  selectively  occluded  at  predetermined times  relative  to  a  critical  moment  in  the  action sequence  (e.g.,  ball  contact).  Participants  predict the  outcome  of  the  action,  usually  by  producing  a  verbal  or  a  simplified  movement  response. High-skilled  players  are  typically  better  at  reliably  anticipating  the  outcome  of  the  occluded pattern  of  play  or  opponent’s  action.  Within  the information-processing approach, this is taken to mean  that  high-skilled  players  distinguish  themselves by their ability to use their extensive knowledge base to process early visual cues to infer the forthcoming event.

Some  have  argued  that  the  expert  perceptual advantage in sport is not limited to the processing of stimulus information but that it also entails the ability to better attend to relevant stimuli or cues. High-skilled athletes appear to be able to visually search the environment in a more efficient manner by  selectively  fixating  longer  on  those  areas  that are  relevant  for  successful  task  performance.  Yet, visual  search  has  also  proven  to  be  highly  sport and task-specific, rendering it hazardous to make inferences  about  general  skill-related  characteristics for visual search. Nonetheless, it is fair to conclude that athletes’ visual search is not only driven by  environmental  events,  but  is  also  directed  by their internal knowledge base. Experts know what are  the  most  informative  aspects  of  an  evolving pattern of play or an opponent’s action, and what aspects are less relevant for further processing.

The Ecological Approach to Perception

The  central  notion  of  the  information-processing approach  is  that  the  environment  is  perceived indirectly  via  an  internal  representation  constructed by cognitive processes that add meaning to  inherently  ambiguous  stimuli.  In  contrast,  the ecological  approach  holds  that  visual  perception is direct. It claims that all the information that is needed for perception (and action) is “out there” in  the  environment.  James  J.  Gibson  argued  that the optic array, which refers to the ambient light that  is  lawfully  patterned  by  the  surfaces  of  the environment, carries information that is rich and sufficient  for  perception.  Because  information in  the  optic  array  is  specific  to  the  properties  of the  environment  (or  the  observer-environment system),  internal  processes  of  enrichment  are redundant. Visual perception therefore entails the pickup  or  extraction  of  specifying  information that resides in the optic array. As a rule, information  is  granted  by  virtue  of  the  observer’s  movements. For instance, a moving observer generates a global expansion pattern in the optic array, the focus of which is specific to the direction of locomotion.  Importantly,  these  movement-induced patterns  in  the  optic  array  (denoted  invariants) also  form  the  basis  for  the  visual  guidance  of action. Accordingly, when steering, the only thing a cyclist needs to do is to move or steer in such a manner that the focus of expansion remains at a position  farther  down  the  road.  Within  the  ecological approach this is referred to as perception– action coupling (or sometimes, and perhaps more appropriately,  information–movement  coupling). A  critical  corollary  of  this  intricate  coupling  of perception with action is that the available information,  and  hence  perception,  is  grounded  in action: Perception and action cannot—and should not—be  understood  and  studied  as  independent processes. Accordingly, the primary objects of perception are thought to be so-called affordances, or opportunities to act.

Within  the  ecological  approach,  perceptual learning is described as convergence or education of  attention,  a  process  along  which  perceivers learn  to  pick  up  specifying  information.  Early  in the  learning  process,  perceivers  can  be  expected to attend to less useful nonspecifying information (i.e., information that is not specific to the environmental  property  of  interest),  resulting  in  misperception.  During  learning,  however,  the  observer comes  to  attend  to  the  specifying  information that  will  enhance  perceptual  accuracy.  Moreover, accurate  perception  (or  action)  not  only  requires the  pickup  of  specifying  information  but  also  an appropriate scaling or calibration of perception or action  to  the  exploited  information.  Hence,  proponents  of  the  ecological  approach  posit  that  in addition to the education of attention, perceptual learning entails a process of calibration.

The Ecological Approach in Sport Research

The concept of perception–action coupling in particular  has  had,  and  continues  to  have,  a  powerful  influence  on  research  in  perception  in  sport.

The  baseball  outfielder  trying  to  catch  a  fly  ball is  a  paradigmatic  example.  Rather  than  inferring the  location  that  the  ball  will  land  based  on  the perception of its current distance and velocity and internal  knowledge  of  ball  flight  characteristics, the  outfielder  should—according  to  proponents of the ecological approach—simply run in a manner that generates systematic changes in the optic array.  During  early  ball  flight,  the  optical  height of  the  ball  changes  according  to  the  location  the ball  will  land  relative  to  the  outfielder.  The  ball will land behind the outfielder when there is vertical optical acceleration. Conversely, in the case of vertical  optical  deceleration  it  will  land  in  front of  them.  This  invariant  not  only  specifies  what the  situation  affords  for  action  (i.e.,  running  forward or backward) but also how to run to get in the  right  place  at  the  right  time  to  intercept  the ball. That is, catchers have been shown to run in a manner that zeroes out or negates optical acceleration or deceleration and keeps optical velocity constant.

The  outfielder  catching  a  ball  underlines  that perception  and  perceptual  expertise  cannot  be investigated  separate  from  action  (i.e.,  without action,  optical  acceleration  cannot  be  negated). Accordingly, the ecological approach has criticized information-processing  approaches  for  doing  just that:  studying  perceptual  expertise  in  sport  using experimental  designs  that  isolate  perception  from action.  Soccer  goalkeepers,  for  instance,  demonstrate  superior  anticipation  (and  interception) when  diving  to  save  real  penalty  kicks  (in  situ) when  compared  to  making  verbal  responses  in response to video clips (as typically required within the  temporal  occlusion  paradigm).  Importantly, these  differences  in  anticipation  are  reflected  by critically different gaze patterns. In addition, faster and more agile goalkeepers are found to wait longer  before  moving  to  block  the  ball  when  tested in  situ.  In  doing  so,  the  pickup  of  information supporting  anticipation  of  the  kick  can  be  based on  (potentially  less  deceptive)  information  that  is only available in the latter part the penalty taker’s actions.  Consequently,  perceptual  expertise  can only manifest itself relative to dexterity in action. Neurophysiologically,  this  would  suggest  that skilled  athletes  rely  on  interacting  and  complementary  contributions  from  the  ventral  (perception) and dorsal (action) visual streams. Therefore ecological  psychologists  consider  it  impossible, or  perhaps  even  misleading,  to  try  capturing  (or achieving) perceptual expertise in sport by examining  (or  practicing)  perception  on  its  own,  decoupled from action.

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