Update user meta of author when post content is viewed

untested but should work

   add_filter('the_content','update_user_score');
    function update_user_score($content){
        global $post;
        $counter = 0;
        $score = get_post_meta( $post->ID, 'ratings_score', true );
        $counter += $score;
        update_user_meta( $post->post_author, 'user_score', $counter);
        return $content;
    }