Poster presented at the 69th American Academy of Forensic Science Annual Meeting, New Orleans, LA, USA. The poster discusses findings of a study of how students identify morphological species

Nigoghosian, Gregory

Nunes, Ludmila

Stamper, Trevor

Weidner, Lauren

English

Purdue E-Pubs

Purdue University Purdue e-Pubs IMPACT Presentations Instruction Matters: Purdue Academic Course Transformation (IMPACT) 2-2017 Teaching Morphological Species Identification to Forensic Science Students: Advantages, Problems and Results Gregory Nigoghosian Purdue University Lauren Weidner Purdue University Ludmila Nunes Purdue University Trevor Stamper Purdue University, stampert@purdue.edu Follow this and additional works at: https://docs.lib.purdue.edu/impactpres  Part of the Educational Assessment, Evaluation, and Research Commons, and the Entomology Commons Recommended Citation Nigoghosian, G., Weidner, L. M., Nunes, L. D., & Stamper, T. I. (2017, February). Teaching Morphological Species Identification to Forensic Science Students: Advantages, Problems and Results. Poster presented at the 69th American Academy of Forensic Science Annual Meeting, New Orleans, LA, USA. This document has been made available through Purdue e-Pubs, a service of the Purdue University Libraries. Please contact epubs@purdue.edu for additional information. Teaching	  Morphological	  Species	  Iden3fica3on	  to	  Forensic	  Science	  Students:	  Advantages,	  Problems	  and	  Results	  	  Gregory	  Nigoghosian1,	  Lauren	  Weidner1,	  Ludmila	  Nunes2	  and	  Trevor	  Stamper1	  1)	  Purdue	  University,	  Department	  of	  Entomology,	  West	  LafayeLe,	  IN	  47906	  2)	  Purdue	  University,	  Department	  of	  Psychological	  Sciences,	  West	  LafayeLe,	  IN	  47906	  	  Subjects	  •  Subjects	  in	  this	  study	  were	  undergraduate	  students	  in	  ENTM	  22820:	  Forensic	  Analysis	  •  96	  students	  par3cipated	  during	  scheduled	  lab	  3me	  Specimens	  •  15	  sets	  of	  8	  specimens	  	  -­‐	  4	  blow	  flies	  and	  4	  beetles	  (Figure	  1)	  •  Blow	  fly	  specimens	  were	  sampled	  from	  the	  Stamper	  Lab	  collec3on	  	  •  5	  different	  species	  of	  blowflies	  (L.	  coeruleiviridis,	  L.	  illustris,	  	  	  	  	  	  	  L.	  sericata,	  P.	  regina	  and	  C.	  macellaria)	  randomly	  labeled	  1-­‐4	  	  	  	  	  	  	  or	  with	  Accession	  number	  •  Beetle	  specimens	  were	  sampled	  from	  the	  Stamper	  Lab	  collec3on	  and	  Lauren	  Weidner’s	  personal	  collec3on	  •  8	  different	  species	  of	  beetles	  (N.	  tomentosus,	  O.	  rugulosum,	  	  O.	  noveboracense,	  N.	  orbicollis,	  N.	  americana,	  C.	  maxillosus,	  	  Histerida	  and	  Dermes3dae)	  randomly	  labeled	  5-­‐8	  in	  the	  set	  	  or	  with	  Accession	  numbers	  	  Procedure	  •  Working	  in	  pairs,	  students	  obtained	  specimen	  sets	  and	  microscopes	  •  Student	  #1	  used	  dichotomous	  key	  (CuLer	  &	  Dahlem	  2004)	  to	  iden3fy	  the	  flies,	  while	  Student	  #2	  used	  field	  guide	  (Castner	  et	  al.	  1995)	  for	  beetles	  •  Once	  both	  had	  iden3fied	  their	  specimens	  they	  would	  trade	  specimens	  and	  iden3fy	  those	  for	  themselves	  •  Acer	  individual	  iden3fica3ons,	  students	  shared	  results	  and	  made	  correc3ons	  to	  ini3al	  iden3fica3ons	  if	  partners	  in	  disagreement	  Nodal	  decisions	  •  Students	  started	  iden3fica3ons	  at	  first	  node	  of	  the	  online	  key	  	  	  	  	  	  	  for	  Calliphoridae	  (Diptera)	  (CuLer	  &	  Dahlem	  2004)	  	  •  At	  each	  node	  students	  would	  record	  observa3ons	  and	  nodal	  	  	  	  	  	  	  decision	  (Figure	  2)	  	  •  Process	  repeated	  un3l	  iden3fica3on	  of	  specimen	  was	  achieved	  Confidence	  •  At	  each	  node,	  the	  subjects	  also	  recorded	  confidence	  in	  decisions	  on	  a	  Likert	  scale	  from	  1	  through	  5	  (1	  strongly	  doubdul	  –	  5	  strongly	  confident)	  Sta7s7cs	  •  Data	  were	  analyzed	  using	  Paired	  Samples	  T-­‐tests	  and	  Independent	  Samples	  T-­‐tests	  where	  appropriate	  •  Data	  were	  considered	  significant	  when	  p	  <	  0.05	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  •  Students	  were	  more	  successful	  at	  using	  the	  single	  photo	  pictorial	  guide	  booklet	  (Castner	  et	  al.	  1995)	  to	  iden3fy	  beetles,	  rather	  than	  the	  dichotomous	  key	  (CuLer	  &	  Dahlem	  2004)	  to	  iden3fy	  adult	  blow	  flies.	  	  •  This	  is	  likely	  due	  to	  the	  iden3fica3on	  of	  the	  selected	  beetles	  being	  easier.	  	  •  The	  differences	  between	  a	  pictorial	  guide	  book	  and	  a	  dichotomous	  key	  would	  be	  beLer	  observed	  by	  using	  the	  family	  of	  insects	  for	  both.	  	  •  No	  significant	  difference	  found	  between	  males	  and	  females	  for	  accuracy	  or	  changing	  answers.	  •  This	  should	  be	  revisited	  with	  larger	  and	  more	  evenly	  distributed	  sample	  sizes,	  to	  conclude	  that	  there	  is	  no	  difference	  between	  males	  and	  females	  in	  iden3fying	  specimens.	  •  STEAM	  students	  showed	  higher	  accuracy	  of	  ini3al	  iden3fica3ons	  of	  flies,	  than	  non	  STEAM	  students.	  •  This	  difference	  could	  stem	  from	  prior	  technical	  experience	  using	  keys	  in	  their	  field	  or	  from	  understanding	  scien3fic	  terms,	  such	  as	  dorsal	  or	  ventral.	  •  Even	  though	  there	  was	  significance,	  this	  should	  also	  be	  re-­‐evaluated	  with	  a	  larger	  sample	  size	  with	  similar	  numbers	  of	  STEAM	  vs.	  Non	  STEAM	  students.	  •  No	  significant	  difference	  observed	  in	  confidence	  between	  sexes	  ,	  and	  majors.	  •  Everyone	  rated	  confidence	  fairly	  high,	  which	  indicates	  overconfidence	  when	  compared	  to	  the	  low	  accuracy	  for	  fly	  iden3fica3ons,	  a	  boLom-­‐up	  cogni3ve	  approach.	  •  Students	  also	  likely	  looking	  at	  wrong	  parts	  and	  features	  while	  thinking	  they	  were	  following	  the	  key.	  •  Control	  of	  sample	  size	  and	  demographic	  informa3on	  was	  difficult	  because	  this	  study	  was	  done	  as	  part	  of	  a	  lab	  in	  a	  Forensic	  Analysis	  course	  that	  does	  not	  discriminate	  in	  enrollment.	  •  Ensuring	  an	  evenly	  distributed	  number	  of	  students	  of	  different	  sexes	  and	  majors	  is	  unlikely.	  •  Pooling	  samples	  across	  semesters	  will	  help	  with	  sample	  size.	  Our	  work	  would	  not	  have	  been	  possible	  without	  the	  effort	  put	  forth	  by	  the	  ENTM	  22820	  Students	  from	  the	  Spring	  of	  2016.	  We	  also	  wish	  to	  thank	  Emily	  Bonem	  from	  the	  Purdue	  University	  Center	  for	  Instruc3onal	  Excellence	  for	  her	  work	  in	  helping	  us	  obtain	  the	  IRB	  approval	  for	  this	  study.	  	  Abstract	  &	  Background	   Methods	  Results	  Results	  (Cont.)	  Acknowledgements	  Gregory	  Nigoghosian	   Lauren	  Weidner	   Ludmila	  Nunes	   Trevor	  Stamper	  	  Following	  this	  presenta3on	  aLendees	  will	  have	  a	  beLer	  understanding	  of	  instruc3ng	  students	  in	  morphological	  species	  iden3fica3on	  through	  the	  use	  of	  dichotomous	  keys.	  A	  dichotomous	  key	  guides	  the	  user	  through	  species	  determina3on	  for	  a	  specimen	  by	  providing	  a	  series	  of	  dual-­‐choice	  nodes	  that	  center	  around	  morphological	  differences.	  Each	  choice	  leads	  to	  either	  a	  new	  set	  of	  dichotomous	  choices	  or	  a	  species	  decision.	  ALendees	  will	  also	  observe	  the	  ability	  of	  students	  to	  successfully	  apply	  this	  method	  to	  unknown	  entomological	  specimens.	  Of	  central	  focus	  to	  training	  students	  in	  species	  iden3fica3on	  is	  the	  idea	  that	  dichotomous	  key	  nodal	  decisions	  take	  the	  user	  down	  specific	  pathways	  to	  a	  final	  species	  designa3on	  by	  not	  focusing	  on	  the	  organism	  whole,	  but	  rather	  specific	  parts	  that	  the	  alpha	  taxonomist	  has	  designated	  as	  important	  diagnos3cally.	  Thus,	  if	  followed	  correctly,	  the	  user	  should	  arrive	  at	  the	  correct	  species	  designa3on	  as	  long	  as	  the	  species	  evaluated	  are	  included	  in	  the	  dichotomous	  key.	  	  	  This	  presenta3on	  will	  impact	  the	  forensic	  community	  by	  providing	  an	  understanding	  on	  how	  accurately	  students	  can	  iden3fy	  adult	  blow	  flies	  (Diptera:	  Calliphoridae)	  using	  a	  dichotomous	  key.	  Insects	  present	  at	  crime	  scenes	  need	  to	  be	  successfully	  and	  accurately	  iden3fied	  to	  aid	  in	  these	  inves3ga3ons	  by	  providing	  informa3on	  such	  as	  3me	  of	  coloniza3on	  (TOC),	  which	  can	  be	  linked	  back	  to	  a	  3me	  since	  death.	  Species	  iden3fica3on	  using	  a	  morphological	  dichotomous	  key	  cogni3vely	  falls	  under	  paLern	  recogni3on,	  which	  is	  part	  of	  the	  percep3on	  and	  problem	  solving	  aspect	  of	  cogni3ve	  science.	  The	  cri3cal	  difference	  between	  other	  forms	  of	  paLern	  recogni3on	  and	  dichotomous	  keyed	  species	  iden3fica3on	  is	  that	  the	  dichotomous	  key	  approach	  provides	  rigorous,	  step-­‐by-­‐step,	  pre-­‐determined	  instruc3ons	  to	  arrive	  at	  the	  paLern	  conclusion	  (a	  species).	  These	  paLerns	  are	  grounded	  in	  an	  extensive	  scien3fic	  literature	  going	  back	  to	  the	  Systema	  Naturae	  by	  Carl	  Linnaeus	  in	  1735	  and	  currently	  outlined	  by	  the	  Interna3onal	  Code	  of	  Zoological	  Nomenclature	  (ICZN	  code).	  If	  followed,	  this	  approach	  forces	  the	  user	  out	  of	  top-­‐down	  processing	  mode	  and	  into	  a	  boLom-­‐up	  processing	  mode,	  whereby	  the	  parts	  of	  the	  organism	  are	  first	  understood	  and	  from	  those	  par3al	  understandings	  a	  full	  understanding	  of	  the	  species	  iden3ty	  of	  the	  specimen	  is	  achieved.	  This	  boLom-­‐up	  approach	  has	  a	  cri3cal	  advantage—it	  eliminates	  the	  possibility	  of	  forming	  biases	  that	  result	  from	  top-­‐down	  processing.	  	  	  	  These	  data	  were	  evaluated	  from	  an	  introductory	  level	  forensic	  analysis	  course	  to	  understand	  the	  student’s	  ability	  to	  u3lize	  a	  dichotomous	  key.	  There	  were	  several	  opportuni3es	  for	  the	  students	  to	  record	  their	  nodal	  decisions	  along	  with	  their	  confidence	  level	  with	  the	  use	  of	  a	  tabular	  format.	  For	  each	  decision	  the	  student	  made,	  they	  ranked	  their	  confidence	  level	  using	  a	  Likert	  scale	  (1-­‐5).	  Along	  with	  individual	  decision	  recording,	  they	  also	  conducted	  a	  post-­‐decision	  comparison	  with	  their	  partner,	  following	  a	  think-­‐pair-­‐share	  ac3ve	  learning	  model.	  If	  their	  answers	  were	  not	  the	  same,	  they	  re-­‐evaluated	  their	  decision	  making,	  along	  with	  a	  re-­‐analysis	  of	  the	  specimen	  un3l	  a	  mutual	  evidence-­‐based	  decision	  was	  reached.	  How	  successful	  the	  students	  were	  in	  making	  the	  correct	  iden3fica3on	  was	  analyzed	  along	  with	  examining	  the	  correla3on	  between	  confidence	  and	  correctness.	  From	  these	  data	  we	  aim	  to	  improve	  student	  training	  in	  the	  use	  of	  dichotomous	  keys	  for	  species	  iden3fica3on,	  which	  can	  then	  be	  used	  to	  provide	  standard	  opera3ng	  procedures	  for	  how	  forensic	  entomologists	  should	  approach	  and	  document	  the	  paLern	  recogni3on	  task	  at	  hand	  in	  a	  way	  that	  limits	  the	  influence	  of	  bias.	  	  Discussion	  1.  Castner,	  J.	  L.,	  Byrd,	  J.	  H.,	  &	  Butler,	  J.	  F.	  (1995).	  Forensic	  insect	  field	  iden>fica>on	  cards.	  Colorado	  Springs,	  CO:	  Forensic	  Sciences	  Founda3on.	  	  2.  CuLer,	  R.	  M.,	  &	  Dahlem,	  G.	  (2004).	  Iden>fica>on	  key	  to	  the	  common	  forensically	  important	  adult	  flies	  (Diptera)	  of	  northern	  Kentucky.	  Department	  of	  Biological	  Sciences,	  Northern	  Kentucky	  University,	  Highland	  Heights,	  KY.	  References	  Following	  are	  the	  results	  for	  a	  sample	  size	  of	  82:	  	  •  Significant	  difference	  between	  the	  Ini3al	  Iden3fica3ons	  of	  Flies	  and	  Beetles	  (Paired	  T-­‐test:	  p=<0.001)	  •  Significant	  difference	  between	  the	  Final	  iden3fica3ons	  of	  Flies	  and	  Beetles	  (Paired	  T-­‐test:	  p=<0.001)	  •  No	  significance	  was	  found	  with	  the	  Fly	  Ini3al	  and	  Final	  	  Iden3fica3ons	  (Paired	  T-­‐test:	  p=	  0.117)	  or	  the	  Beetle	  Ini3al	  and	  Final	  Iden3fica3ons	  (Paired	  T-­‐test:	  p=	  0.287)	  •  No	  significant	  differences	  between	  males	  and	  females	  iden3fica3on	  or	  either	  flies	  or	  beetles	  (p	  >	  0.05)	  The	  sample	  was	  split	  into	  53	  females	  and	  29	  males:	  	  •  No	  significant	  differences	  between	  males	  and	  females	  changing	  answers	  from	  correct	  to	  incorrect	  •  Independent	  T-­‐tests:	  •  Female	  vs.	  Male	  change	  from	  correct	  to	  incorrect	  Fly	  Iden3fica3ons:	  p	  =	  0.687	  •  Female	  vs.	  Male	  change	  from	  correct	  to	  incorrect	  Beetle	  Iden3fica3ons:	  p	  =	  0.736	  	  Of	  82	  students,	  there	  were	  21	  STEAM	  and	  52	  Non	  STEAM,	  and	  9	  undecided	  (Not	  Used):	  	  •  Significance	  was	  found	  only	  in	  the	  difference	  between	  STEAM	  and	  Non	  STEAM	  Ini3al	  Iden3fica3ons	  of	  Flies	  (Independent	  T-­‐test:	  p=0.01)	  •  No	  significant	  differences	  between	  STEAM	  and	  Non	  STEAM	  majors	  for	  subsequent	  iden3fica3ons	  Figure	  1	  Figure	  2	  0.00%	  10.00%	  20.00%	  30.00%	  40.00%	  50.00%	  60.00%	  70.00%	  80.00%	  90.00%	  100.00%	  Flies	  Ini3al	  	   Flies	  Final	  	   Beetles	  Ini3al	  	   Beetles	  Final	  	  Accuracy	  Flies	  Ini3al	  	  Ini3al	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  Final	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  Ini3al	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  Final	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  Flies 	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  Beetles	  Not	  STEAM	  STEAM	  Figure	  5:	  Percentage	  of	  students,	  divided	  by	  STEAM	  vs.	  Not	  STEAM	  majors,	  who	  correctly	  iden3fied	  specimens	  0%	  1%	  2%	  3%	  4%	  5%	  6%	  7%	  8%	  Flies	   Beetles	  Change	  from	  Correct	  to	  Incorrect	  Series1	  Series2	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  Flies 	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  Beetles	  F male	  Male	  Figure	  4:	  Percentage	  of	  males	  and	  females	  that	  changed	  answers	  from	  correct	  to	  incorrect.	  0%	  10%	  20%	  30%	  40%	  50%	  60%	  70%	  80%	  90%	  100%	  Accuracy	  Flies 	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  Beetles	  Ini3al	  Final	  Figure	  3:	  Percentage	  of	  students	  who	  correctly	  iden3fied	  specimens	  ini3ally	  and	  acer	  partner	  consulta3on	  (Final).	  A	  A	  B	   B	  0	  1	  2	  3	  4	  5	  Female	   Male	   Non	  STEAM	   STEAM	  Final	  Fly	  Confidence	  Female	  Male	  Non	  STEAM	  STEAM	  Figure	  6:	  Student	  confidence	  in	  their	  final	  iden3fica3on	  decision	  separated	  by	  sex	  and	  major.	  Confidence	  data	  comparing	  male	  vs.	  female	  students	  and	  students	  in	  STEAM	  vs.	  Non	  STEAM	  majors:	  	  •  No	  significant	  difference	  observed	  between	  males	  and	  females	  in	  confidence	  (p	  >	  0.05)	  •  No	  significant	  difference	  observed	  between	  students	  in	  STEAM	  vs.	  Non	  STEAM	  majors	  (p	  >	  0.05)	  •  Overall	  student	  s	  had	  high	  confidence	  scores,	  even	  though	  accuracy	  was	  not	  high	  for	  fly	  iden3fica3on.	  

Teaching Morphological Species Identification to Forensic Science Students: Advantages, Problems and Results

https://docs.lib.purdue.edu/cgi/viewcontent.cgi?article=1025&amp;context=impactpres

Teaching Morphological Species Identification to Forensic Science Students: Advantages, Problems and Results

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