unshift(@($this->{Memory}),$this->{Senses});
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To dereference the array ref, you need curlies, not parentheses, i.e. @{$this->{Memory}}

my $this = {
    Memory => ["foo"],
    Senses => "bar",
};

unshift @{$this->{Memory}}, $this->{Senses};

use Data::Dumper; print Dumper $this;

__END__
$VAR1 = {
          'Senses' => 'bar',
          'Memory' => [
                        'bar',
                        'foo'
                      ]
        };
[download]

Thx it works (obvious it was ^^).
But I don't et it, I thought that the "->" dereferences, doesn't it ?
when I did print $this->{N}[0]{Value}; it worked ok, so whats the difference ?
Why didn't I needed to dereference there ?
and whats "Dumper" is this really required ? (I prefer to avoid module dependencies)
Thx again

The thing is that unshift needs an array (syntactically), not an array reference. And the way to get an (entire) array from a reference is to say @$aref, or @{ $something->{that}{returns}[1]{aref} } for more complex expressions.  To address a single element of the array, you'd say $aref->[$index].

(The Data::Dumper module is to easily print out complex data structures. I just used it for demo purposes — you of course don't need it to unshift the value.)

-> is dereferencing a hash that has nothing to do with your question.

Your question is about dereferencing the array referenced by $this->{N}.

-> is dereferencing a hash that has nothing to do with your question.

Your question is about dereferencing the array referenced by $this->{N}.

On a side note, as of Perl v5.14, shift, unshift, push, and pop can now take a reference to an unblessed array as their first argument, which will be automatically dereferenced, although it is considered experimental.