Good job searching to find this old thread! Your question is not related to JSON, but rather to perl data structures. See perlref.

You should get in the habit of using Data::Dumper to examine your complex data structures. In this case, you still were unclear on how to access the nested data, but examining the structure is always the first step.

(Note that jsonToObject in the OP is deprecated.)

Here's an example that shows how to get your arrays. It's commented so you can see what's going on, and it deliberately uses more steps than optimal to be clear (if you really wanted to build separate arrays, you should probably use map).

#!/usr/bin/perl
use strict;
use warnings;
use feature qw/ say /;
use Data::Dumper;
use JSON;

my $data =  qq# 
{
    "items" : [
        {   "name" : "Theodor Nelson",
            "id": "_333301"
        },
        {   "name": "Morton Heilig",
            "id": "_13204"
         }
        ]
}
#;

my $obj = from_json( $data );
my @names;
my @ids;

say Dumper $obj;
# $obj is an anonymous hash with one key, 'items'

my @items = @{ $obj->{'items'} };
# The value of the key 'items' is an anonymous array.
# Here for simplicity we copy it into a new array.
# We access it by deferencing it using @{  }

foreach my $item ( @items ) { 
  # Each element of the anonymous array is a hashref.
  # So $item is a hashref, not a scalar
  my $name = $item->{'name'};
  my $id   = $item->{'name'};

  push @names, $name;
  push @ids,   $id;
}

say 'Names: ' . join ', ', @names;
say 'IDs: ' . join ', ', @ids;

__END__
[download]

A more idiomatic way to put the data into a hash keyed by ID as you suggested above:

#!/usr/bin/perl
use strict;
use warnings;
use feature qw/ say /;
use Data::Dumper;
use JSON;

my $data =  qq# 
{
    "items" : [
        {   "name" : "Theodor Nelson",
            "id": "_333301"
        },
        {   "name": "Morton Heilig",
            "id": "_13204"
         }
        ]
}
#;

my $obj = from_json( $data );
my %names;

$names{ $_->{'id'} } = $_->{'name'} for @{ $obj->{'items'} };

while ( my( $id, $name ) = each %names ) { 
  say "$id: $name";
}

__END__
[download]

Output:

$ perl 651544-2.pl
_13204: Morton Heilig
_333301: Theodor Nelson
$
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And finally, how to access the names directly in the object:

#!/usr/bin/perl
use strict;
use warnings;
use feature qw/ say /;
use Data::Dumper;
use JSON;

my $data =  qq# 
{
    "items" : [
        {   "name" : "Theodor Nelson",
            "id": "_333301"
        },
        {   "name": "Morton Heilig",
            "id": "_13204"
         }
        ]
}
#;

my $obj = from_json( $data );

say ${ $obj->{'items'}->[1] }{'name'};
#   ^  ^             ^   ^   ^      ^
#   |  |             |   |   |      |
#   |  is an  arrayref   |    -----------
#   |                    |               |
#   |  first element of which is a hash  |
#   |                                    |
#   the variable is value of the 'name' key    

__END__
[download]

Hope this helps!