diff --git a/src/main/scala/org/xcit/nback/generators/SkewedSequenceGenerator.scala b/src/main/scala/org/xcit/nback/generators/SkewedSequenceGenerator.scala
index 6e82300..c30d341 100644
--- a/src/main/scala/org/xcit/nback/generators/SkewedSequenceGenerator.scala
+++ b/src/main/scala/org/xcit/nback/generators/SkewedSequenceGenerator.scala
@@ -1,7 +1,10 @@
 package org.xcit.nback.generators
 
+import scala.util.Random
+
 /**
   * Reference: Ralph2014 - Appendix A
+  *
   * @param alphabet Alphabet used to generate the sequence, excluding the target item
   * @param target Target character.
   * @param N The set size of stimuli to remember (n in n-back). Default is 3.
@@ -21,14 +24,38 @@
   L2: Double = 4)
     extends SequenceGenerator {
 
-  private class TrialType extends Enumeration {
-    //TODO Types: LURE1, LURE2, TARGET, DISTRACTOR
+  /**
+    * Types of each trial (L1, L2, T, or D).
+    */
+  private object TrialType extends Enumeration {
+    val LURE_BEFORE_TARGET, LURE_AFTER_TARGET, TARGET, DISTRACTOR = Value
   }
   override def generate(trials: Int): String = {
     //1. Init alphabet and buffer
-    //2. For each trial, generate a random type
+
+    var trial = 0
+    while (trial < trials) {
+      trial += 1
+      //2. For each trial, generate a random type (L1, L2, T, or D)
+      val trialType = nextTrialType(trials)
+    }
     //3. Based on the generated type, generate the item and append it to the buffer
     //4. Convert buffer to string and return it as result
     ???
   }
+
+
+  /**
+    * Defines next trial types randomly. It returns L1, L2, T, or D (Ralph2014).
+    * Random range: [1, trials] (both are inclusive based on ralph2014!)
+    * @param trials number trials
+    * @return
+    */
+  private def nextTrialType(trials: Int): TrialType.Value = { Random.nextInt(trials + 1) + 1 } match {
+    case rnd if rnd <= L1 => TrialType.LURE_BEFORE_TARGET
+    case rnd if rnd < rnd && rnd <= L1+L2 => TrialType.LURE_AFTER_TARGET
+    case rnd if rnd <= L1 => TrialType.TARGET
+    case _ => TrialType.DISTRACTOR
+
+  }
 }